MIL-HDBK-274 - Barringer and Associates, Inc.

Transcription

MIL=HDBK0274(AS)
1NOVEMBER 1983
MILITARY HANDBOOK
ELECTRICAL GROUNDING
FOR AIRCRAFT SAFETY
NO DELIVERABLE
OATAREOUIRED
BYTHISDOCUMENT
EMCS
MIkHDB1:-274(AS)
1 November 1983
NAVAL AIR SYSTFNS COMMAND
WASHINGTON, DC 20361
)
Electrical Grounding for Aircraft Safety
MIL-HDBK-274(AS )
1 November 1983
1. This handbook was developed for use by the Naval Air Systemo Command and will
provide a single source reference to ensure that aircraft under it6 jurisdiction
are properly grounded and bonded. This handbook ie not intended to be referenced
in purchase opecificationso except for informational purpoee6~ nor shall it
6uper6ede any specification requirements,
2. This document reflect6 the latest equipment and procedures used for the
electrical grounding and bonding of Naval ●ircraft. It ia the intent to review
this handbook periodically to insure its completeness and currancy.
3. Beneficial comments (recommendations, additions, deletions) and any pertinent
data which may be of uee in improving this document should be addrts~ed to the
Commanding Officer, Naval Air Engineering Center, Engineering Specifications and
Standards Department (Code 9313). Lakehurst. New Jersey 087330 by using the
self-addressed Standardization Document Improvement Propoeal (DD Form 1426)
appearing at the end of this handbook or by letter.
.
.
ii
MIL-HDBK-274(AS)
1 ?lovembcr 1983
FOREWORD
otandard rtfcr?ncc murc?
to
ThiB hmdbook hsa bem pr~psr~d to provide ● singlt.
be used by naval aircraft oper~tiono and maintenance? pwconncl
(iacludint public
worh department p~rtonnel) to ● rmurt that the ●irctsft under their jurisdiction
● re properly @rid .af@lg ●lcctrictlly grounded
and bonded,
Tht pbilooophieal position and techuieal information preoettt~d in this hcndof A ptwioua naval study documented in lfAVAM R?port
book ~re bsmtd upon results
Pro8rsm.11
Thst
5181-1000 titl.d~ ‘tAirframe
Elcctrlcal Groundius R@quirment8
program claarly demonstrat~d
that haurds
●xist during s1l sircraft wolutiow~
●nd
●stablish~d that thcr- ● rt valid t~chnical reasons to ●lectrically ground ●ircraft
for ●ll evolutions, including ●ll ●sprcts of maintensnc?. fu?ling, stor- hsndlingo
It slso r~cognized that ● rigorous grounding philosophy is r?quir~d
●nd parking.
vhich~ when strictly followed. will maximiz~ personnel ●nd ●ircraft safety.
The grounding methods pr~sented in this handbook make ● cl~ar distinction betw~m
#tatic grounding ●nd powtr grounding,
Static grounds are dcfinrd as those points
having impedances of lesE than 10,000 ohms r?fercnced to ?arth. Powr grounds arp
to the
defined so those points having impedance of lQSS than 10 ohms refermccd
power cystem neutral.
Grounding methode prcsent~d in this handbook rrquirt mtatic grounding of ●irersft
stereo loadings hot r~fuelingt ●nd ●ll
during fueling/defu@ling, parked evolutions
external power ●volitions with di~sel-gen~rst~d (ac or dc) power courcec. ThP9@
requirements ●pply to both fixed wing and rotary wing ●ircraft evolutions
(including hovming,
HIFR, ●nd RAST). Bonding ●nd grounding by triangulation io
required during fueling/defueling evolutions.
Hangar-based maintenance ●volitions requiring ●xternal power (ac or dc) with
grounded (earthed) neutrsl (eg, fscility power or MMG-lA) must be connected to a
power ground prior to the introduction of ouch power.
On board ship, tiedown chains cannot be used to static ground ●ircraft*
grounding cablea mu6t be used to connect the aircraft to the deck padeye.
padeye it an acceptable static grounding point.
SeParate
The deck
During Flight Line Electrical Distribution System (FLEDS) operations, aircraft
to the
must be bonded to the FLEDS ●srthed neutralo such ● s Connecting the ●irfr=e
Distribution Box Acaembly (DBA) hardware.
During Mobile Electrical Pov@r Plant (kfEPP) external power configuration, it is
recommended that in ●ddition to ●ny raquired grounding, the aircraft be separately
power
bonded to its mobile powm source. Aircraft uming 28V dc di?ael-gm?rated
only are ●xempt from this bonding requirement.
iii
MIL-EDBK-27A(AS)
1 Novmber
1983
This handbook contains compreheumiv~ grounding procedur~s on ●ll ●ctive,
operational type ●ircrtft pr~semtly in the naval inventory. Information on
aircraft still in us? but not covered in this handbook can b~ obtained from the
folloving ●gency:
lJAVAIRSYSCOU
El@ctromagnetics Branch, 5161
Washington. DC 20361
Autovon:
222-7788
Commercial:
(202) 692-7788
iv
F!IL-HDBK-274(AS)
1 November 1983
CONTENTS
Paragraph
1 ●0
1.1
1.2
SCOPE ...................................................
hrpose ......... ............,*m**. *** ****am******# ....
Referenced Documents .........=..... ...................
1
1
2
2.0
2.1
2.2
2 ●3
2.4
2.5
AIRCRAFT GROUNDING AND BONDING HETNODS ..................
Land-bas@d aircraft ...................................
Carrier-bas~d aircraft ................................
Ilelicoptpr hovering ...................................
Ext@rnal ●l~ctricnl power . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Aircraft fueling when using ?xt~rnal ●l~ctrical
power (A-6) ....................... . . . . . . . . . . . . . . . . . . . .
130t fueling ...........................................
4
4
149
205
209
OPERATIONAL GROUNDING CONCERNS. ............... ..........
Static el~ctricity ....................................
Energy sourc~s ........................................
Operational prOCedUrC6 .........*...... .*..=*sao.oDa.*c
Special considerations ................................
Actual grounding problems .............................
Measurement of static ground ●nd ●lectrical
power ground points ...................................
Grounding hardware/receptacle coneiderationa .. ........
Grounding hardvare military specification nhe~t
.
reference llst ....a..cot. .~o*@.O-cO-.Q@C OO~C.S..O*...
222
222
223
231
235
238
4.0
4.1
4.2
4.3
4.4
4.5
4.6
THEORETICAL BASIS FOR AIRCRAFT GROUNDING ................
Electrostatic theory ..................................
Sccnarioc .............................................
Energy ● ourcee. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Airframe/personnel electrical parameter . .............
Damag? threshold levels ...............................
Analysis ..............................................
242
242
262
242
257
260
261
5.0
5.1
5.2
5.3
5.4
5.5
5.6
5.7
TESTING AND IDENTIFICATION OF GROUND POINTS ...os*OOmQOmQ
Theoretical background ................................
k’lQSt8UKb?.UieIIt
eqUipQeUL ...........*.... ..............*.o
Ground points measurement procedures..”................
Schedule for resistance testing of ground points ......
Identification of ground point . ................... ...
ThP USP of mooring eyes as static ground point . ......
Reaistancc nteaaurementa for alternate
grounding and bonding points ..........................
265
265
265
269
272
272
272
2.6
3.0
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
●
v
217
220
240
240
241
273
MIL-HDBK-274(AS)
1 November 1983
FIGURES
)
Figure
2-1
2“2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
A-3 sircraft ~roundinge park~d •?olution,.,~s~t.,., .,,,,
A--3 aircraft
grounding,
futlinU/d?futling evolution,...,
Iiangar-bssed
A-3 aircraft grounding, maintenance
?volutiong Obt~,gaa ~g~gmagaa,moeegaea ,aOeeaa @mBe.aggaee.9
Apron-baBed A-J ●ircraft &rounding. maintenance
wolutionO.COcOOoO ~,a.0@,QC90CgO$S$Q ~OOStg~~oSSoOCOOaO St
grounding
parked solution. ..,..,,.,,. .,,,
A-4 ●ircraft
grounding. fu?ling/defueling ●volition .....
A-4 ●ircraft
Hangar-based A-4 aircraft grounding, maintenance
●volition.. .,..,. .................,,,,.g,.,,egeaog~ .e.~.
Apron-based A-4 aircraft grounding, maintenance
evolution ...................................g...........
A-4 aircraft grounding, stores loading/unloading
evolution ...................................O ,.......e.
A-6 ●ircraft grounding, parked ●?olution ................
A-6 aircraft grounding. fueling/defueling ●volition .....
●volition .......................................g.......
grounding, maintenance
Apron-based A-6 aircraft
●volutlon ....o. ,,,,...,,.,..., ..........................
A-6 ●ircraft grounding, store8 loading/unloading
●volition ......~............~.............~ge a**m.*..*.
aircraft grounding, parked evolution ................
A-7
A-7 ●ircraft grounding, fueling/defueling cvolucion .....
Hangar-based A-7 aircraft grounding. maintenance
evolution. .,....... .....................................
Apron-based A-7 aircraft grounding. maintenance
evolution ......................................9..,...*.
A-7 aircraft grounding, atoree loading/unloading
evolution ...............................................
AH-1 aircraft grounding, parked evolution. ..,..,..,,. .,.
AH-1 aircraft grounding, fueling/defueling ●volition ....
aircraft grounding, maintenance
Hangar-based AH-1
●
2“10
2-11
2-12
2-13
2-14
●
2-15
2-16
2-17
2-18
2-19
2-20
2-21
2-22
QVOIUtlOKI
2-23
2-24
2-25
2-26
2-27
2-28
2-29
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Apron-baaed All-1 aircraft grounding. maintenance
●volition ......................................0*..*.9D.
AN-1 aircraft grounding. stores loading/unlosding
evolution ...............................................
AV-8 aircreft grounding, parked ●volution ...............
AV-8 aircraft grounding, fueling/defueling ●volition ....
Hangar-baoed AV-8 aircraft grounding, maintenance
●volition ...............................................
Apron-baaed AV-8 aircraft grounding. maintenance
evolution ...............................................
AV-8 aircraft grounding, etorea loading/unloading
evolution ...............................................
vi
6
7
8
10
11
13
●
14
15
.
17
lB
19
21
22
24
25
26
27
29
31
32
33
34
36
37
38
39
41
42
44
.
.
XIL-HDBK-274(AS )
1 Novmber
1983
FIGURES - Continued
Figure
2-30
2-31
2-32
2-33
2-34
2-35
2-36
C-1 ●ircraft grounding, park~d ●volution ................
c-1 aircraft grounding? fueling/dPfueling Qvolution.c--=
Hangar-based C-1 aircraft grounding, maintenance
.
evolution ......~....m~ .....m,e.~g.aa.~e..n. .a.~.~a~~-...
Apron-based C-1 ●ircraft grounding. maintenance
evolutlon.a..,.. ...e~bg ......e.. ..............*. ... ....*
c-130 aircraft grounding. parked ●volition. .m.ee.=..e...
C-130 ●ircraft grounding, fueling/defueling solution...
Haagar-ba@ed C-130 aircraft grounding, maintenance
.
. . . . . . . ..O...S.O~*~*
..m
. . . ..aOW
evolutlon.Qa.Oa **m****.*
Apron-bas*d C-130 aircraft grounding, maintenance
.
9u.m
. . . ...*.
evolution ........~...agn..gn ..eo..a**.m*a*a
CM-53 aircraft grounding, parkrd ●volution ..............
CH-53 aircraft grounding~ fueling/d@fu@ling evolution.~’
Hangar-baaed CH-53 ●ircraft grounding. maintenance
●volition ...............e... .o..~...a.g .................
Apron-based CR-53 aircraft grounding. maintenance
●volition..*... ..*.**~..*V .... ..D.*.**.m.*.. .*.**..*.*~
CH-S3 aircraft grounding, stores loading/unloading
.
evolution ......e .....g ....~ .............................
E-2 aircraft grounding, parked ●volution ................
E-2 aircraft grounding. fueling/defueling ●volition .....
Hangar-bas?d E-2 aircraft
grounding wint~nanc?
●volution...g.g •~m~.an.~~g~w.e .......**...**. .....a~g,..
Apron-baaed E-2 aircraft grounding~ maintenance
evolution .........e..~.eb...sm .go.ga~.~e.~aog ,....aa~..a
EA-6 aircraft grounding, parked evolution ..............i
u-6 aircraft grounding, fueling/defueling evolution ....
Hangar-based EA-6 aircraft grounding, maintenance
.
evolution .........~ ........~.oa...ae..e.~. w~q~.~~~o.e..m
Apron-baaed EA-6 aircraft grounding. maintenance
evolutiong..a~m •*~OOa*g*O*..WO ......g ....*... ....aa..ga~
EA-6 aircraft grounding, stereo loading/unloading
evolution .....•a......e..e.~ .Sm***..~**.** *m*a.**a.*...
F-4 aircraft grounding, parked Qwolution ..............o.
F-4 aircraft grounding, fueling/defueling solution . ....
Hangar-based F-4 ●ircraft grounding -intenance
●volition ............~ ............g.....................
Apron-ba#ed F-4 aircraft grounding~ maintenance
evOIUtlOn.*OO.. .*.~*.*** .......*..*~...D*.D.* •#*e*~**.*a
F-4 aircraft grounding, ctorea loading/unloading
evolutlon..O..O gm.oo..~ae~~mg~ ..0g*8e*g.@ ....9s.........
F-14 aircraft grounding, parked evolution ...............
F-14 aircraft grounding, fueling/defueling ●volition...,
Hangar-based F-14 ●ircraft grounding, maintenance
evolution...~. ......g..a..~e .~amegagemag... •~..~***+m***
●
2-37
●
2-38
2-39
2-40
2-41
●
2-42
2-43
2-44
2-45
2-46
2-47
2-48
2-49
2-50
2-51
●
2-52
2-53
2-54
2-55
2-56
2-57
2-58
2-59
vii
45
46
47
49
50
51
53
54
56
57
58
59
61
62
64
6S
66
68
69
70
71
73
74
75
77
78
80
81
82
84
—
MIL-HDBK-274(AS)
1 November 1983
FIGURES - Continued
Figure
2-60
2-61
2-62
2-63
2-64
2-65
2-66
2-67
2-68
2-69
Apron-based F-14 aircraft grounding, maintenance
evolution .. .............................................
F-14 aircraft grounding, stores loading/unloading
ewolutlon ....................*.....*,,.* ................
F-18 aircraft grounding, parked evolut ion ...............
F-18 aircraft grounding, fueling/defueling evolution ....
Hangar-based F-18 aircraft grounding, maintrnanc?
.
evolution ...............................................
Apron-based F-18 aircraft grounding. maintenance
evolution ............................*.. ................
F-18 aircraft grounding, stores loading/unloading
evolution ...............................................
H-46 aircraft grounding, parked evolution ...............
H-46 aircraft grounding, fueling/defuQling evolution ....
Hangar-based H-46 aircraft grounding, maintenance
evolution ................................. . . . . ...**....
Apron-based H-46 aircraft grounding, maintenance
evolution ...............................*. ..............
H-46 aircraft grounding, etoreB loading/unloading
evolut~on ................................. .............
OV-10 aircraft grounding, parked evolution .......... ....
OV-10 aircraft grounding, fueling/defueling evolution.. .
Hangar-based OV-10 aircraft grounding, maintenance
evolution ....................................o....e. .g..
Apron-ba6cd OV-10 aircraft grounding, maintenance
evolution ...............................................
OV-10 aircraft grounding, stores loading/unloading
evolution ..............................* ................
P-3 aircraft grounding, parked ●volut ion ................
P-3 aircraft grounding, fueling/defueling evolution .....
Hangar-based P-3 aircraft grounding. maintenance
evolution ..............................................9
Apron-based P-3 aircraft grounding, maintcnanc~
evolution ...............................................
P-3 aircraft grounding, stores loading/unloading
evolution ..............................................
S-3 aircraft grounding, parked evolution ................
S-3 aircraft grounding, fueling/defueling evolution .....
Hangar-based S-3 aircraft grounding. maintenance
evoluclon ...............................................
Apron-based S-3 aircraft grounding, maintenance
evolution ....................................~a.........
S-3 aircraft grounding, stores loading/unloading
evolution ...................................m.....a.....
SH-2 aircraft grounding, parked evolution ...............
SH-2 aircraft grounding, fueling/defucling evolution...,
●
2-70
2-71
●
2-72
2-73
2-74
2-75
2-76
2-77
2-78
2-79
2-80
2-81
2-82
2-83
2-8&
2-85
2-86
2-87
2-88
viii
85
87
88
89
90
92
93
95
96
97
98
100
101
103
I04
105
107
108
109
111
112
114
115
116
118
119
121
122
123
HIL-HDBK-274(AS)
1 November 1983
FIGURES - Continued
figure
2-89
2-90
Hangar-based SH”2 ●ircraft grounding Maintenance
.
124
evolutxoneg..et .~~eege~~~~~ag. •g.~gageg~ebgmo •gg.~e....g
Apron-ba6ed SE-2 aircraft grounding, maintenance
126
evolutiongggmm. ....O.*.~ ....9~ •aee.u~~.eq~mem **.8 D*D.*0
SH-2 aircraft grounding, storer Ioadingfunloading
127
evolution.. .eQ.~s.w...e~aeg. ................*...*.* ....*
129
SH-3 ●ircraft grounding, perked evolution ...............
130
SH-3 ●ircraft grounding~ fueling/defueling •JO~utiOn9***
Haagar-based SH-3 aircraft grounding, maintenance
131
evolution.OoC*O gg~ge.agaaga~ew .W....me.m..se. ..**mD*a*m9
Apron-based SH-3 aircraft grounding~ maintenance
.
132
evolution ......eo.. ....= .........8.... ..................
SH-3 aircraft grounding. stores loading/unloading
134
evolution .....•aam~.gge..... .O...- .......e...**.D.~*.***
135
SH-60 aircraft grounding, parked evolution ..............
137
SH-60 aircraft grounding. fueling/defu~ling evolution=””
Hangar-based SH-60 aircraft grounding, maintenance
138
evolutionOOOQ- ...o......*.m. .*.mg.*...w*.* w9**9.*=9*. *0
Apron-based SH-60 aircraft grounding, maintenance
139
evolution. a..,...., ........*a** .............9...........
SH-60 aircraft grounding, stores loading/unloading
141
evolution ..... ..8.......**** .g..*a*..gg@g@g ~a@D**g..WS
142
TH-57 aircraft grounding, park~d evolution ..............
143
TH-57 aircraft grounding, futling/defueling evolution...
Hangar-baaed TH-57 aircraft grounding, maintenance
145
●volutxona...8n •geam.m+~g..bn. gebmg. .aggeeog B89w89...9
Apron-based TN-57 ●ircraft 8roundin8* maintenance
146
evolutionoO0.80@ •OWa~~.m..,.a.*a *..=*********** •*~*.*~n
147
UC-12 aircraft grounding, parked ●volution ..............
148
UC-12 ●ircraft grounding, fueling/defuelin8 •volution~t”
Hangar-bsaed UC-12 ●ircraft grounding, maintenance
150
evolution., eme~. S*.g*g .............*..*...g...aD .**,*..O
Apron-ba8ed UC-12 ●ircraft grounding, maintenance
151
●volutionem ....b m.....gggbg.gbg
~e.e...eem.gm.gm ..g.bg..
Carrier-baoed A-3 aircraft~ fueling/defueling
evolutionOO.ogo~ mg?..e.g.agbg.a ...9*..as*a999.w ~m~s**fi. 153
154
Carrier-baaed A-3 aircraft~ maintenance ●volition...**,*
Carrier-baaed A-4 aircraft, fueling/defueling
155
evolution ........4.......*...... .,..*...D**gab.@ ........
157
Carrier-baa?d A-4 aircraft, maintenance solution ......*
Carrier-based A-6 aircraft, fueling/defueling
158
evolution. ..oCO .*9*ga*..*~.De@ ...s.9 ......... ....*....*
159
Carrier-based A-6 aircraft, maintenanc~ ●volition .......
Carrier-baaed attack (A-3, A-4. A-6* A-7* AV-8# W-6)
aircraft~ parked evolution ●nd stores loading/
161
unloading evolution,..o,. ~,.,........~..~. .,.......~-,o~
●
2-91
2-92
2-93
2-94
2-95
2-96
2-97
2-98
2-99
●
2-1oo
2-101
●
2-102
2-103
2-204
●
2-105
●
●
2-106
2-107
2-108
2-109
●
2-110
●
2-111
2-112
2-113
2-114
●
2-115
2-116
ix
MIL-HDBK-274(AS )
1 November 1983
FIGURES - Continued
Figure
2-117
2-118
2-119
2-120
2-121
2-122
2-123
2-124
2-125
2-126
2-127
2-128
2-129
2-130
2-131
2-132
2-133
2-134
2-135
2-136
2-137
Carrier-based A-7 aircraft, fueling/defu@ling
.
. . . . . . . . . . . . . .
cvolutzon .............*.*... .* . ...*.*..*..
Carrier-baaed A-7 aircraft, uintenance
solution .......
Carrier-based AR-1 aircraft, fueling/defu@ling
.
●volition., .............................................
Carrier-based AR-1 aircraft, maintenance evolution ......
Carrirr-bao~d AV-8 aircraft, fueling/defueling
evolution ...............................................
Carrier-based Av-8 ●ircraft, maintenance evolution ......
fueling/defueliug
Carrier-bas~d C-1 aircraft,
●volition ..........................................*..*.
Carrirr-bao~d C-1 sircraft, maintenance ●volition .......
Carrier-based CR-53 ●ircraft, fueling/defu@ling
.
●volition..,.. ..........................................
Carrier-based CH-53 ●ircraft, maintenance wolutiou .....
Carrier-based mpecial ●lectronics (E-2) aircraft,
parked evolution ●nd stores loading/unloading
●volition ...............................................
Carri~r-bae~d E-2 aircraft. fueling/defueling
.
evolution .. .............................................
Carrier-ba@~d E-2 ●ircraft, maintenance ●volition .......
Carrier-based EA-6 aircraft, fueling/defueling
evolution ...............................................
Carrier-based EA-6 sircraft, maintenance evolution ......
Carrier-based F-4 ●ircraft, fueling/defueling
evolution ...............................................
Carrier-baaed F-4 aircraft, maintenance ●volition .......
Carrier-based fighter (F-4, F-14. F-18) aircraft.
parked ●volution and stores loading/unloading
.
evolution ....o..........................................
Carrier-bas~d F-14 ●ircraft, fueling/defueling
●volition..,.., .........................................
Carrier-based F-14 ●ircraft, maintenance evolution.,...,
Carrier-based F-18 ●ircraft, fueling/defueling
Qvolutlon ..... ...**.*.*,**.* ******...**.. .*.*, ,****..*
Carrier-baaed F-18 aircraft. maintenance solution ......
Carrier-based R-46 aircraft, fueling/defueling
.
evolution ...............................................
maintenance ●volition ......
Carrier-baaed H-46 ●ircraft,
Carrier-based ●nti-submarine (S-3) aircraft, parked
.
●volution and stores loading/unloading evolutlon.o
......
Carrier-based S-3 aircraft, fueling/defueling
evolution ............................*....* ....g.be.~...
●volition .......
Carrier-based S-3 aircraft, ~intenance
Carrier-based helicopter (AR-l. CH-53. H-46. WI-2.
SH-3, SH-60) aircraft, parked wolution
and stores
loading/unloading evolution. ............................
●
2-138
2-139
2-140
2-141
2-142
2-143
2-144
●
x
162
163
164
166
167
168
169
171
172
173
174
176
177
178
179
181
182
183
185
186
187
189
190
191
193
194
195
197
?fIL-HDBR-274(AS)
1 November i983
FIGURES - Continutd
Figure
2-145
Carrier-based S1-2 aircraft, fueling/defuelin8
●volition ...... •..w~ga.gagga~.a *~~.m~***s..w”w. ****.**
Carrier-baa@d SH-2 aircraft, maintenance ●volition..,...
Carrier-bas?d SH-3 aircraft~ fue~inB/defu@~ing
. .
evolutton.C.40. ...~e,~.~~~.~~~ •.*9*~.~~*...** ***.***.
Carrier-based SH-3 aircraft,
maintenance ●volition ......
Carrier-based SH-60 aircraft, fueling/defueling
.
evolutlon..~so. ,~,sem~a......a ......*....9.B* •*e.g8ngg9~
Carrier-ba~Pd SH-60 aircraft, maintenance evolution...,.
Static grounding of hovering helicopter during load
transfer ................................................
Static grounding of hovering helicopter during
refueling evolutlon (HIFR).**~~*... ................-~~o
Grounding hovering helicopters employing RAST system....
Carrier-based aircraft grounding when using
deck edge power .........................................
Apron-ba6ed aircraft grounding when using FLEDS.tDO.Do. o
Hangar-based aircraft grounding when using ?JWG-lA MEPP..
Carrier-based aircraft grounding when using NC-2A MEPP..
Apron-baaed aircraft grounding when using NC-8A MEPP ....
Apron-ba@ed aircraft grounding when ueing NC-1OC MEPP...
A-6 aircraft grounding during fueling/defueling with
●xternal power supplied by a diesel ●ngine driven
MEPP (Nc-2A. NC-8A, or NC-lOC) ........O .................
A-6 aircraft grounding during fueling/defueling vith
external pover supplied by an electric motor driven ?4EPP
(MMG-lA)
* . ...* , .*,* .*..., * .. . .
. . .m ..
Aircraft grounding during fueling/defueling with
external power supplied by FLEDS ... ,...* .. * *** *,* *
Aircraft eupplied with external power ...................
Typical flight line ●lectrical distribution
(FLED) 0y8t= .. .......0 ...........ea.9a meee99g0e0e0a” *90
Lightning discharge .............=... .,.o.o...*so*c***0*o
Helicopter grounding wand. ..............................
●
2-146
2-147
●
2-148
2-149
2-150
2-151
2-152
●
2-153
2-154
2-155
2-156
2-157
2-158
2-159
2-160
2-161
● ●
2-162
●
●
●
● ●
●
●
●
●
3-1
3-2
3-3
3-4
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4“9
4-10
4-11
4-12
4-13
● ●
●
●
● ●
●
● ●
●
● ●
●
●
●
Cloud-inducing charge on aircraft ................aa .....
Possible return path for accumulated charge during
remote discharge of cloud ... ...............*..**.- .....*
Charge accumulation on clothing .........................
Possible discharge of accumulated charg~ ................
Charge separation due to fuel flow. .....................
Ground power faull scenario .................. . . . . . . . . . . .
Lightning 6trike to parked aircraft .....................
Various cloud discharges ..,...... .......................
.
domain, ...................
Lightning current pulsQ, ttme
“
domain ...............
Lightning current pulse, frequmcy
Charge transf~r of a current waveform ...................
Simulated RC network ....................................
Aircraft acting as capacitor ............................
xi
X98
199
201
202
203
204
206
207
208
210
211
212
214
215
216
218
219
221
227
228
230
237
244
244
246
247
247
250
253
255
256
256
257
259
259
HIL-HDBX-274(AS)
1 l’?ovember1983
)
FIGURES - Cent inued
.
Figure
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
Simple electrical circuit utilizing Ohmfs law ...........
Illustration of earth resistance ........................
Illustration of ●arth sh?lla ............................
l%r~c-tcminal
test technique ...........................
Three-~erminal fall of po~en~ial method ~eat ●emp ......
Two-~erminal method Lest setup ..........................
Measured ground point identification ....................
Mooring eye details .....................................
Test s~tup for resistance meaaurem~nta of alt~mat~
grounding and bonding points ............................
xii
266
267
268
268
270
271
274
275
276
HIL-HDBK-274(AS)
1 Novemb?r 1983
TABLES
Table
4-I
4-II
4-III
4-IV
4-V
Lightning characteristics ...............................
SWry
of electrical energy ●urcea . ...................
Electrical parameters ...................................
Sunmaryofdamagc
threshold Iwels ................... ...
Potmtial hazard relationship to ●nergy sources ●nd
scenarios ...................ea~. .....****m**am** ..ea...
●
.,,
X111
252
258
260
261
264
PIIL-KDBK-274(AS)
1 Novmaber 1983
SECTION 1
1.1 ~
The purpo~e of this hsndbook is to provide aircraft maintenance
personnel with the information r?quired for ●lectrical safety grounding of each
type of operational aircraft in the U.S. Navy inventory.*
In ●ddition. this
handbook provides background information
pertaining to the opertiotml concerns for
aircraft grounding- static ●lcctricity theory ●nd how it ●ffects ●ircraft. ●nd
technique used for measurement of grounding points. This handbook is divided into
five mections as follows:
SECTION
SECTION
SECTION
SECTION
SECTION
1
2
3
4
5
-
SCOPE
AIRCRAFT GROUNDING AND BONDING Hl?TllODS
OPERATIONAL GROUNDING CONCERNS
THEORETICAL BASIS FOR AIRCRAFT GROUNDING
TESTING AND IDENTIFICATION OF GROUND POINTS
1.1.1 This handbook is intended for uae by all U.S. Naval aircraft operational
and maintenance personnel including maintenance officers and public works officiala
for the purpose of enmuring that each aircraft ia properly grounded and that the
grounding system ie adequate for this purpose.
Sections 1 ●nd 2 ● re intended
primarily for uae by line maintenance persotmel.
Sections 3 and 4 contain material
intended for those desiring to obtain additional theoretical and background
information.
Section 5 is ●ssential for public works department personnel. Each
section is designed to stand alone.
1.1.2 The information contained in Section 2 is intended to be ueed by line
maintenance personnel.
This section provides step-by-,tep in8truction8 for
grounding each of the ●ircraft in the Navy inventory during each of the following
evolutions:
parkedo fueling/defueling, maintenance, ●nd storen loading/unloading.
Each ●volution is shown in a separate illustration depicting the particular
aircraft with proper grounding/bonding cables connected, The illustrations show
primary grounding points and also provide alternate grounding points should the
primary grounding point be inacceeaible.
Aloo provided on the illustrations are
pertinent cautions ●nd warninge to be observed during the groundin8 procedure.
Accompanying each illustration is a step-by-step procedure fo,rgrounding/bonding
the particular aircraft.
1.1.3 Section 3 provides background ●nd general information neceaaary to
understand the rationale behind the requirements for grounding and bonding. This
section a160 discus-es the grounding problems and hazarda encountered in the
everyday ground handling
of aircraft during flight operation.
Energy &ourcee ●nd
grounding effects are identified. The aircraft scenarios or servicing aituationa
(evolutions) are introduced and the aircraft safety problems associated with ●ach
are described.
In addition, a brief discussion of static ●lectricity and how it
affects aircraft operation is provided.
●U.S. Navy aircraft uae power ●quipment not equipped with ground fault interrupter
(GFT).
MIL-IiDBK-274(AS)
1 November 1983
1.1.4 Section 4 detailn basic el~ctrostatic theory and its application to
aircraft grounding.
Sources of @tatic electricity associated with ●ircraft
operation are also deBcribed.
These include triboelectric effects,
fuel flow.
induced charge, and friction. Hazarda from ground power faults, rf ●nergy, ●nd
lightning are presented. Also included in this section are descriptions of
aircraft electrical parameters and a discussion of hazardous threshold ●nd th~
possible dangers they present to personnel and aircraft safety. ‘I%? section ●lso
illustrates that prop?r grounding will reduce these hazarda.
1.1.S Section
5 is intended
for ume by the public works department personnel ●nd
provideB a description of the methods and techniques uted to measure the resictanc~
of the grounding ayatem. Also included in Section V in ● suggested schedule for
accomplishing the measurement of ground points. identifying ground points~ the use
of mooring ~yes as static ground points, and a diecueeion of the teat ●quipment
l~~ed to meaaure ground point reaietance,
1.2 ~
handbook.
The following documents are referenced
in this
m
MS27574
Cable Configuration,
MS3493
Connector, Plug and Cap Electric, Grounding
14sO090298
Connector, Receptacle, Electric, Grounding
MS33645
Receptacle, Grounding,
Ms25083
Jumper Assembly, Electric Bonding ●nd Current Return
MIL-C-83413
Connector, Electric Ground
US25486
Connector, Plug, Attachable,
115/200 volt 400 hertz
Ext. Electric Power. Aircraft
M825488
28 Volt DC Operating Power
Ext. Electric Power, Aircraft,
MS25487
28 Volt DC. Jet Starting.
Ext. Electric Power. Aircraft,
2
Grounding
Installation of
MIL-NDBX-274(A8 )
1 Novembm
1983
NAVAIR AIR-5181 -1OOO
Airframe Electrical Grounding R@quir=entS
Final Report, 17 ?eb 1981
NAVAIR 00-80T-96
U.S. Navy Support Equipmut,
Safety
Manual, 1 April 1981
NAVAIk 19-45-1
Tablefor
Index ●nd Applications
Power Plants, 1 Sept~ber
1972
liAVSEA 0P4 Vol. 2 (5th Rev.)
Asununitfon Afloat, 15 February 1972
NAVSEA OP5 Vol.
Anmtunition ●nd Explosives Aehore, 1S October
MIL”HDBK-419
1 (4th
Rev.)
Progrm
Basic Mandliw
?lobile
md
Electric
1974
Grounding, Bonding, md Shielding for Eltctronfc
Equipments ●nd Facilities, 21 January 1982
141L-HDBK-274(AS)
1 November 1983
SECTION 2
Thi# ●ection provideu step-by-Btep procedures for grounding and bonding operational ●ircreft in the Navy inventory. Variou~ handling evolutions. both land-baas+d
and carrier-bssed, of the different aircraft arp described and illustrated with
●ppropriate varninga ●nd caution8. Note that the word “carrier’t is meant to
refer to ●ny ship which supports aircraft flight operation.
By referring to the particular ●ircraft procedures in this section, organizational nuintenance pereonncl will be able to properly determine aircraft grounding
requirements before beginning other servicing. Recommended grounding and bonding
locations are illuetrat?d. If conditions prevent the use of these locations, a
must be performed to verify that the
resistance check using ● milliob~eter
alternate location is an acceptable grounding or bonding attachment point. A
location ia an acceptable grounding or bonding point if the resistance meatiured
from the point to the airframe is less than 10 milliohms. Using a milliohmmeter
(Shallcross Model 670A or equivalent), connect one probe to the known aircraft
Observe the
grounding point and the other probe to the proposed grounding point.
milliohmneter for a reading of less than 10 milliohms.
If the milliohmmeter
reading is less than 10 milliohms, the propoeed grounding point is acceptable.
Painted, corroded, dirty, greasy areas or areas of composite materials should not
be used for grounding points.
In addition, if the intended grounding point is
loosely connected to the aircraft structure by way of bearings or springs, an
unacceptable inte~ittent
ground or bond could result.
When employing grounding cables, the specific type of connector r~quired on the
ends will be determined by the aircraft type. Hany Navy aircraft do not have
grounding receptacles available in other than the fueling area, and they are therefore not readily available for use as the static grounding point on the aircraft.
In these inetances a cable having an M83413-1 connec~or on each end may be used.
one end attached to an approved static ground point, the other to a clean metal
area of the aircraft.
Cablee shall be of 7 x 7 construction, .094 nominal diameter wire rope with
:{.S3413-1connectors at each end. Cable length shall be determined by user
requirements.
The maximum resistance shall not exceed 0.5 ohms for the cable
configuration (MS27574),
2.1 ~
The following paragraphs provide step-by-step procedures for grounding land-based aircraft.
Evolution$ requiring exte~al
pmer
are detailed in paragraphs 2.4 through 2.6.
Fueling evolutions shown here do not indicate external electrical power. These
illustrations apply to gravity fueling as well as hot fueling from fu~l trucks.
Figures 2-160 and 2-]61 illustrate grounding and bonding procedures for the A-6
using external electrical power during fueling. The grounding and bonding procedures for other aircraft requiring external electrical power during fueling are
similar.
)
MIL-HDBK-274(AS)
1 November 1983
The fuel hose bond cable must be connect~d to an appropriate ground on the
aircraft prior to attaching the fu?l hoee.
NOTE: For purpoees of clarity and practicality
handbook will be defined as followe:
electrical ~rounds in this
Power ground: An ●pproved ground point with
ohms to the power system neutral.
Static Ground: An ●pproved
than 10.000 ohms refermced
●n
imped@nce less than 10
ground point that hac
to earth.
●
impedance of 1Q8S
When performing maintenance in the FLEDS ar~a, airframes must b~ grounded and
bonded an indicated in figure 2-155. Where a bonding cable is required b?tveen thr
UEPP and the aircraft, the illustrations contained in thig handbook $hOW #eParat@
bonding and power cables for the purpose of clarity only. In ●ctual Practic@B
however, these two cables should be tied together.
cl?
2.1.1 ~
To ground A-3 ●ircraft when in the parked evolution, proceed as follows (eQe figure 2-l):
a.
b.
c.
Attach grounding cable with 1483413-1 cl~ctrical ground connector
(clamp type) to a certified static Sround or padey~ (l).
Connect free end of grounding cable to nose landing gear (2). If
grounding
cable tO
this location ie not accessible. then Conmct
main gear ciedown ring (typical ●lttrnate grounding point).
To remove grounding cable, reverse above procedures.
To ground A-3 ●ircraft when fueling or
defueling, proceed as follows (see figure 2-2):
a.
b.
c.
d.
e.
f.
Attach grounding cable with M83413-1 ●lectrical ground connector
(clamp type) to a c~rtified static ground or padeye (X).
Conn~ct free end of grounding cable to nose landing gear (2). If this
location is not acceueible, then connect grounding cable to main gear
tiedown ring (typicaX alternate grounding point).
If using fuel truck, attach its grounding cable to a certified static
ground or pad~ye (3).
Connect fuel truck bonding cable to noee landing gear.
When fueling/defueling ●volution has been completed- wait a minimum of
2 min before removing bonding cable.
To remove grounding or bonding cable, reverse above procedure~”
.
2.1.3 A-?
bas~d ~P
To ground A-3 aircraft during
maintmance
evolution in the hangar, proceed as follows (see figure 2-3):
a.
b.
c.
Attach grounding cable with M83413-1 electrical ground connector
(clamp type) to a certified power ground (1).
Connect free end of grounding cable to nose landing gear (2). If this
location is not accessible, then connect grounding cable to main gear
tiedown ring (typical alternate grounding point).
5
FIGURE 2-1.
A-3 ~d
WARNING
TIE DOWN CHAINS CAN NOT
BE USED TO GROUND AIRCRAFT
SEPARATE GROUNDING CABL[
MUST BE USEO
.
‘v~
.
CAEJTtON
EARTH GROUND POINT MUST BE
FREE OF PAINT ANO CORROSION
NOSE GEAR
LOOKING FORWARD
F!IL-HDBK-274(M)
I November 1983
7
MXL-HDBX-274(AS)
1 November 1983
s
ii
)
●
MIL-KDBK-274(AS )
1 November 1983
.
.
.
2.1.4 ~-3 ~e
@v~
(~
To ground A-3 aircraft when in the maintenance evolution on the apron with tht
mobile electrical power plant (MEPP) plugged into aircraft. proceed as follows (oet
figure 2-4):
a.
Attach grounding cable with U83413-1 electrical ground conn~ctor
(clamp type) to ● certifi~d static ground or padeye (1).
NOTE :
b.
c.
d.
e.
If the MEPP i- an ●lectrically-driven
must be used.
type. th@n a P~@r
ground
If this
Connect free ●nd of grounding cable to nose landing gear (2).
location is not accessible, then connect grounding cable to main gear
Attach bonding cable with H83413-1 el~ctrical ground connector to nose
landing gear (3).
Connect free end of bonding cable to a bare metal area on the MEPP
(4).
To r~ove grounding or bonding cable, reverse above procedures
To ground A-3
,aircraft when in the maintenance? evolution on the apron using the flight line
electrical distribution system (FLEDS), proceed as follows (see figure 2-4):
a.
b.
c.
d.
e.
(clamp type) to a certified static ground or padeye (l).
Connect free end of grounding cable to nose landing gear (2). If
location is not accessible, then connect grounding cable to main
Attach bonding cable with M83413-1 electrical ground connector to
landing gear (3).
Connect free end of bonding cable to a bare metal area on the DBA
as the stud or bolt (4) (see figure 2-155).
To remove grounding or bonding cable, reverse above procedures.
this
War
nose
such
.
2.1.6 ~
To ground A-4 aircraft when in the parked ●volution, proceed as follows (ace figure 2-5):
a.
b.
c.
d.
(clamp type) to a certified static ground or padeye (1).
Connect free end of grounding cable to pylon grounding receptacle
(typical) (2).
If grounding receptacles are not accessible, then using a grounding
cable with M83413-1 ●lectrical ground connector at each ●nd> follow
ctep a, and connect free end of grounding cable to notie gear tiedown
ring (typical alternate grounding point).
9
CDNNECTOFI
CAUTION
EARTH GRO~D POINT
MEJS7BEFREE OF
PAINT AND CORROSION
CERTIFIED GFIOUNO
[LESS THAN 10.CKXI
OHMS)
I
i)o
MEPPOR FLEDS
EX1WR SOURCE.
WARNING
TO STUO OR
BOLT ON DEEA
TO
SERVICE
CABLE
MIL-XDBK-274(M)
1 Novmnber 1983
\
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In
1
CN
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11
MIL-HDBK-274(A8)
1 November 1983
2,1.7 A-4 ~
To ground A-4 aircraft when fueling or
defueling. proceed as follows (see figure 2-6):
a.
b.
c.
d.
e.
f.
8*
Connect
free end of grounding cable to pylon grounding receptacle
(typical) (2).
If grounding receptacle
are not accessible, then using a grounding
cable with M83413-1 electrical ground connector at each end, follow
step a, and connect free end of grounding cable to noer gear tiedown
If using fuel truck, attsch its grounding cable to a certified static
ground or padeye (3).
Connect fuel truck bonding cable to nose gear tirdown ring (4).
When fueling/defueling evolution ha8 been completed, wait a minimum of
To remove bonding or grounding cable, reverse above procedure.
~~e
=v~
2.1.8
~~ed
maintenance in the hangar, proceed as follows (ace figure 2-7):
a.
b.
c.
d.
(clamp type) to a certified power ground (l).
(typical) (2).
cable with a M83413-1 electrical ground connector at each end, follow
step a, and connect free end of grounding cable to nose gear tiedown
.
.
.
@VO2.1.9 A-4 ~
(~d
To ground A-4 aircraft vhen in the maintenance evolution on the apron with MEPP
plugged into aircraft, proceed as follows (see figure 2-8):
a.
NOTE :
b.
c.
d.
e.
f.
If the MEPP is an ●lectrically-driven
must be used.
type, then a power ground
(typical) (2).
If grounding receptacles are not ●ccessible, then using a grounding
cable with M83413-I
electrical
ground connector at each end, follow
Attach bonding cable with M83413-1 ●lectrical ground connector to noee
gear tiedown ring (3).
(4).
TO r~ove grounding or bonding cablt, reverse above procedures.
12
J
.—
XIL-HDBK-274(AS)
1 Novtmber 1983
13
!fIL-EDBK-274(AS)
1 Novmber
1983
I
.
\
I
M
FIGURE 2-8.
.
A-4 a~
.
.
WARNING
TIE DOWN CHAINS CAN vOT
BE USED TO GROUND AIRCRAFT.
SEPARATE GROUNOING CABLE
MUST BE USED
‘vo~
.
LE
ON
EPTACLE
5011
823
MIL-HDBU-274(AS)
1 Novemb~r 1983
2,1.10
~-4 1~
To Bround A-4
●ircraft when in the maintenance ●volution on the apron using ?Ll!IXO proceed aa
follow
(see figure
●.
b,
C.
d.
t.
f.
2-8):
Attach
grounding cable with Md3413-1 ?lrctricsl ~round conntctor
(clamp type) to c certified otatic ground or pmd~y~ (1).
cnd of groundin~ cable to pylon grounding r?ccptacl~
Connect free
(typical) (2),
If grounding r?c?pt@cles are not ●cceasiblo.
then uoinu a grounding
cablo with 1483413-1 cltctrical
~round conrwctor ct Meh sndo follov
ctop ●s ●id connect free ●nd of grounding cabl~ to noa? #MT tiedown
rhe
(typicsl ●lternate groundlns point).
Attach
bondin~ cable with M83413-1 ?I?ctrical ground connpctor to
nose go8r tiedown ring (3).
Connect free ●nd of bonding cable to ● bare metal ● rea on the DBA
such •~ the stud or bolt (4) (see figure 2-155).
grounding
or bonding
cable,
rev~rse
●bove procedures.
TO rmove
2,1011 ~
ator~o loading or unloading. proceed
●.
b.
c.
d,
●s
follow
(oee figure 2-9):
Attach grounding cable with M83413-1 ●lectrical ground connpctor
(typical) (2).
If Srounding receptacle
are not ●ccessible. then u~in~ ● moundint
c-ble with MB3413-1 ●lectrical
ground connector ● t ●ach ●nd, follow
step ● , and connect fr?e end of grounding cable to nose g~ar tiedown
ring (typical alternate grounding point),
To ground A-6 aircraft when in the parked
evolution, proceed as follows (Bee figure 2-10):
●✎
b.
c.
Attach grounding cable with M83413-1 ●lectrical ground conn?ctor
Connect free end of grounding cable to tail bumper (2). If this
location is not accessible, then connect 8rounding cable to main
gear tiedown ring (typical alternate grounding point).
To remove grounding cable, reverse above procedure-.
2.1.13 A-6 ~
defueling. proceed se follows (ace figure 2-11)$
a.
b.
c.
Attach grounding cable with ~3413-1
electrical ground connector
Connect free ●nd of grounding cable to tail bumper (2). If this
gear tiedom ring (typical alternate grounding point).
16
)
MIL-HDBX-274(M)
1 November 1983
.
w
.
a
.
\
‘d
‘\
I
I
.
I
u.
17
—.-. .-
IUL-RDBK-274(AS)
1 November 1983
\
)
i
MIL-HDBK-274(AS)
1 November 1983
u
,.
,’
]$1
——
MIL-HDBK-274(AS)
1 November 1983
d.
e.
f.
Connect fuel truck bonding cable to nose landing gear (4).
When fueling/defueling evolution has been completed, wait a minimum
of 2 min before removing bonding cable.
.
2.1.14 ~e
e~
maintenance evolution in the hangar, proceed as follows (see figure 2-12):
a.
b.
c.
location is not accessible. then connect grounding cable to main
2.1.15 A-6
P D@ed
ed
Into
TO ground
A-6
aircraft when in the maintenance evolution on the apron the
~
apron with MEPP plugged into aircraft, proceed as follows (see figurp 2-13):
a.
NOTE :
b.
c.
d.
e.
If the MEPP is an electrically-driven
murst be used.
gear tiedown ring .(typical alternate grounding point).
nose gear tiedown ring (3).
(4).
To remove grounding or bonding cable, reverse the above procedures.
2.1.16 A-6
ed
aircraft when in the maintenance
follows (see figure 2-13):
a.
b.
c.
d.
e.
(u~
To ground A-6
evolution on the apron using FLEDS, proceed as
grounding point).
gear tiedown ring (typical alternate
nose landing gear (3).
such as the stud or bolt (4) (see figure 2-155).
20
)
MIL-HDBK-274(AS)
1 November 1983
\
‘ ‘+..
/
1’
-“L\\
IL;
MIL-HDBK-274(AS )
1 November 1983
—
MIL-HDBK-274(AS)
1 November 1983
2.1.17
A+
.
evo~
stores loading or unloading, proceed as follows (see figure 2-14):
a.
b.
c.
1~
Attach grounding cable with M834]3-1 electrical ground connecttr
To remove grounding cable. reverse above procedures.
2.1.18 A-7~
To ground A-7 aircraft when in the parked evolution, proceed as follows (see figure 2-15):
a.
b.
c.
d,
Attach grounding cable with M83413-1 electrical ground connec.ar
Connect free end of grounding cable to forward fuselage grounding
receptacle (typical) (2).
a grounding
If grounding receptacles are not accessible, then using
cable with ?483413-1 electrical ground connector at each end. follow
2.1.19 A-7 fu~
defueling, proceed
a.
b.
c.
d.
e.
f.
go
as
follows
(see
2-16):
figure
If grounding receptacles are not accessible. then using a grounding
If using
fuel truck, attach its grounding cable to a certified static
Connect fuel truck bonding cable to nose gear tiedown ring (4).
When fueling/defueling evolution has been completed. wait a minimum
To remove bonding or grounding cable, reverse above procedures.
2.1.20 A-7
maintenance in the hangar. proceed as follows (Gee figure 2-17):
a.
b.
Attach grounding cable with M83413-I electrical ground connector
(1).
(clamp type) to a certified power ground
23
{
—
--
MI L-HDBK-27k(AS)
1 November 1983
-’
d.
‘v’ y(
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‘M&Es
MIL-HDBK-274(AS)
1 November 1983
\
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L
5
.—
L’
25
——.—.
—.
MIL-HDBK-274(AS )
1 November
1983
w
MIL-HDBK-274(A8)
1 November 1983
.
m
1’
.
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27
.—
——
MIL-EDBK-274(As)
1 November 1983
c,
d.
If grounding receptacles arc not accessible, then using a grounding
cable with U83413-1 ●lectrical ground corm-ctor ● t ●ach end- follow
etep a, ●nd connect free ●nd of grounding cable to noee gear tiedovn
TO r~ove grounding cable. reverse above procedures.
.
.
.
.
.
&-7 ~
~
TO ground A-7 aircraft when in the -intenance
wolution on the apron with
MEPP plugged into aircraft, proceed ● s follows (see figure 2-18):
2.1.21
a.
ROTE:
b.
c.
d.
e.
f.
If the MEPP is
must be used.
b.
c.
d.
●.
f.
type.
then
a power
ground
Connect free end of grounding cable to fo=ard fuselage grounding
cable with MB3413-1 ●lectrical ground connector at each end, follow
etep ● , ●nd connect free end of grounding cable to nose gear tiedown
Connect fre~ ●nd of bonding cable to a bar~ metal area on the MEPP
(4).
2.1.22 A-7 ~*
●✎
an electrically-driven
.
cva~
To ground A-7
evolution on the apron using FLEDS, proceed as
(clamp type) to ● certified power ground (l).
Connect free ●nd of grounding cable to foward fuselage grounding
at ●ach end, follow
cable with X83413-1 electrical ground connector
step a, ●nd connect free ●nd of grounding cable to noee gear tiedown
ring (typical ●lternate grounding point).
Attach bonding cable with M83413-1 ●l~ctrical ground connector to
nose gear tiedovn ring (3).
Connect free end of bonding cable to a bar? metal ● rea on the DBA
such aa the stud or bolt (4) (see figure 2-155).
To remove grounding or bonding cable. reverse above procedures.
28
)
P!IL-HDBK-274(As)
1 lfovmb~r 1983
29
MIL-EDBK-274(AS)
1 November 1983
stores loading or unloading,
a.
b.
c.
d.
2.1.24.
●volution
proceed as follows (see figure 2-19):
Connect free end of grounding cable to fomard fuselage grounding
If grounding receptacles ar~ not ●ccessible, then using ● grounding
cable with M83413-1 electrical ground connector at each ●nd, follow
To r~ove grounding cable, reverse above procedures.
@l
~
To ground AlI-l aircraft when in the parked
a.
b.
c.
Attach grounding cable with M83413-I electrical ground conn~ctor
Connect free ●nd of grounding cable to front right towing ring (2).
then connect grounding cable to
If this location is not accessible,
front left towing ring (typical alternate grounding point).
above procedures.
To renove grounding cable, reverse
2.1.25 &i-l ~
or defueling, proceed
a.
b.
c.
d.
e.
f.
b.
c.
●s
.
To ground AH-1 aircraft when fueling
follows (ace figure 2-21):
Attach grounding cable with U83413-1 electrical ground conn~ctor
Connect free end of grounding cable to front right towing ring (2).
If this location is not accessible, then connect grounding cable to
front left towing ring (typical alternate grounding point)
If using fuel truck, ●ttach its grounding cable to ● certif: ●d static
Connect fuel truck bonding cable to front right towing ring (4).
To r~ove grounding or bonding cable, reverse above procedures.
2.1.26 ~-l
maintenance ●volution
a.
.
To ground AH-1 aircraft during
in the hangar, proceed as follows (see figure 2-22):
Attach grounding cable with M3413-1
(clamp type) to a certified power ground (I).
Connect free end of grounding cable to front right towing ring (2).
If this location ie not acceeaible, then connect grounding cable to
30
L
[
FIGURE 2-19.
v3!!!!h
IL-7 ~
‘“”’-”
EARTH GROUND POINT
MUST BE FREE OF
PAINT ANO CORROSION
GROUNDING CABLE cONNECT TO GROUNDING
RECEPTACLE ON
FORWARD FUSELAGE
CERTIFIED GROUND
OR
PADEYE
(LESS THAN 10,~OHMSl
w
=
~–
CAUTION
.—-
W!
/.
.
.
.
?’$”)“”’”7
la’
\
——-
WARRING
BE USED TO GROUND AIRCRAFT
SEPARATE GROUNDING CABLE
MUST BE USED
-——
—... .
—
?tIL-HDBX-274(M)
1 November 1983
)
32
MIL-B.DBK-274(AS )
1 Nowmber 1983
a
ii
/(//’
/“”
33
HIL-HDBK-274(As)
1 November 1983
FfIL-HDBK-274(AS)
1 November 1983
.
.
.
.
.
m-l ~
To ground AH-1 ●ircraft when in the maintenance
evolution
on the
XEPP plugged into aircraft. proceed as follws
(see figure 2-23):
2.1.27
~
with
Attach grounding cable with
(clamp type)
to a certified
●.
NOTE :
apron
M83413-1 electrical
ground connector
etatic
ground or padeye
(l).
must be used.
towing ring (2).
Connect free end of grounding cable to front right
If this location is not accessible~ then connect
grounding
cable
to
b.
NOTE :
c.
.
If the MEPP ia a diesel ●ngine-driven
bonding requirement is waived.
type, then the following
bonding cable with M83413-1 electrical ground connector to
right
towing ring (3).
front
Connect free end of bonding cable to ● bar? metal area on the MEPP
(4).
To remove grounding or bonding cable- reverse above procedures.
Attach
d.
e,
To ground AV-8 aircraft during
2*1.28 m-l
2-24):
stores loading or unloading, proceed as follows (see figure
●.
b.
c.
2,1.29
Attach grounding cable with U83413-1 ●lectrical ground connector
(clamp type) to a certified etatic ground or padeye (l).
towing
ring (2)0
Connect free end of grounding cable to front right
If this location in not accessible, then connect Srounding cable to
front left towing ring (typical
alternat~
grounding
point).
To remove grounding cable, r~verme ●bove procedures.
.
To ground AV-8 aircraft
proceed as follows (nee figure 2-25):
bV-B~
●volution
●
.
b.
c.
b.
in
the
parked
Connect free end of grounding cable to outrigger gear tiedown ring
If this location is not accessible, then connect
grounding
(2).
cable
to bottom part of outrigger gear leg (typical ●lternate
grounding point).
To remove grounding cable, reverse ●bove procedure.
2.1.30 &-fl ~
or defueling, proceed
a,
when
.
.
as follows (see figure 2-26):
●vo ~
when fueling
grounding cable with M83413-1 electrical ground connector
static
(clamp type)
to a certified
Connect free end of grounding
cable to outrigger g~ar tiedown ring
is not accessible,
then connect 8rounding
(2). If this location
Attach
35
m
w
(
FIGURE 2-23.
=
N
NOTE
THE BONDING Ot THE
MEPP TO THE AIRCRAFT
IS SHOWNONLY FOR
ILLUSTRATIVE PURPOSES
IT IS f!EOUIREOONLY
WHEN THE MEPP IS
AN ELECTRICALLY DRIVEN
TYPE
CAUTION
EARTH GROUND POINT
MUST BE FREE OF
pAINT AND CORROSION
CERTIFIE6GROUND
(LESS THAN 10.000OHMS)
Tnwl
-- ....
\_#/
\\
NC -8A
EXT POWER
LE F T SIOE
o-
WARNlffi
BE USEO TO GROUND AIRCRAFT,
MUST EIEUSED
HIL-HDBK-274(AS)
1 ?Jovmnber 1983
37
FIGURE 2-25.
AY-8 ~
WARMING
TIE OOWN CHAINS CAN NOT
BE USEO TO GRO(JNO AIRCRAFT.
MUST BE USEO
CAUTtON
EARTH GROUND POINT
MuS1 BE FREE OF
PAINT AND CORROSION
=
!!’o
1
CEF4TIFIED GROUND
oFi
PAOE YE
ILESS THAN 10.000 OHMS)
GROUNOINGCABLE
CONNECT TO
TIE OOWN RING
.
.
\
J
TYPICAL
ALTERNATE GROUNOING i
POINT USING CONNECTOR
/7
.Dclll
11
-x
u
??IL-EDBK-274(AS )
1 November 1983
\
Ilm$?
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39
MIL-HDBK-274(AS)
1 November 1983
c*
d.
e.
f.
cable to bott~ part of outrigger gear leg (typical ●lternate
grounding point).
If using fuel truck, attach ita grounding cable to a certified mtatic
Connect fuel truck bonding cable to main wheel axle (4).
When fueling/defueling evolution has been completed, wsit ● minimum
of 2 tin before removing bonding cable.
@WO~
2.1.31 M-8 ~
To ground AV-8 aircraft during
maintenance evolution in the hangar, proceed as follows (see figure 2-27):
a.
b.
c.
Connect free end of grounding cable to outrig~er gear tiedown ring
(2). If this location ia not accessible, then connect grounding
gear leg (typical ●lternate
cable to bottom part of outrigger
grounding point).
To remove grounding cable, revera~ above procedure.
.
.
.
U-8
(~
~
TO ground AV-8 aircraft when in the maintenance ●volution on the ●pron
with KEPP plugged into aircraft, proceed as follows (see figure 2-28):
2.1.32
a.
Attach grounding cable with M834X3-1 ●lectrical ground connector
NOTE :
b.
c.
d.
e.
muet be used.
b.
●
power ground
end of grounding cable to outrigger gear tiedown ring
Connect free
(2). If this location iB not accessible, then connect grounding
cable to bottom part of outrigger gear leg (typical ●lternate
grounding point).
Attach bonding cable with ?183413-1 ●lectrical ground connector to
main wheel axle (3).
area on the NEPP
Connect free end of bonding cable to ● bare metal
(4).
To remove
grounding or bonding cable. r~verae the above
procedures.
2.1.33 ~-fl~
follovs (see figure 2-28):
a.
type, then
evo
evolution
on
To ground AV-8
the apron u6ing FLEDS, proceed ati
Attach grounding cable with U83413-1 electrical ground connector
Connect free end Of grounding cable to outrigger gear tiedown ring
(2). If this location is not acceaaible, then
connect grounding
cable to bottom part of outrigger gear leg (typical alternate
grounding point),
40
)
FIGURE 2-27.
CAUTION
EARTH GROUND POINT
MUST BF FREE OF
PAINT ANO cORROSION
●d wa
~
.
●
.
.
rn
rrmm
EXT PWR SOURCE
MEPP OR fLEOS
EXI POWER CORD
WARNING
w USED TO GROUND AIRCRAFT.
MuST BE USED
n
CABLE
2
o
{
CAUTION
TIE DOWN RING
MuST BE FREE OF I
PAINT AND CORROSION
Mfm13 1
~ CONNECTOR
\
lml
llJ
?6>
\’y-tir
FARTHGROUNDPWINT
GROUNDING CABLF CONNECT TO
TIE DOWN RING
IIfxL-EDBK-274(A8)
1 November 1983
C.
d.
e.
Attach bonding cable with M3413-1 el~ctrical ground con!wctor to
main wheel axle (3),
Connect free end of bonding cable to a bare metal ●r?a on the DBA
such se the stud or bolt (4) (ace figure 2-155).
To remove grounding or bonding cable.
reverse ●bove procedures.
2.1.34 U-R
stores loading or unloading, proceed -a follws
a.
b.
c*
To ground AQ-8 ●ircraft duriaa
see figure 2-29):
Attach grounding cable with M83413-1 ?l@ctrieal ground connector
(clamp type) to a certified static
ground or pad~~e (l).
Connect free end of grounding cable to outrigger gear tiedown rims
(2). If this location is not ●ccessible, then connect grouadinc
cable to bottom part of outrigger g?ar leg (typical ●lternat?
grounding point).
To remove grounding cable. reverse above procedures.
.
To ground C-1 aircraft when in the parked
2.1.35
~-l
d e~
●volition, proceed as follows (see figure 2-30):
a.
b.
c.
Attach grounding cable with X83413-1
●l~ctrical ground connector
Connect free end of grounding cable to note gear towing ring (2),
this location is not acceasible~ them connect Srounding cable to
main gear tiedom ring (typical alternate grounding point).
To remove grounding cable. rever8e above procedures.
If
To ground C-1 ●ircraft when fueling or
2,1.36 ~-l
defueling, proceed aa follows (ace figure 2-31)$
(clamp type) to a certified static
If
b. Connect free end of ground cable to nom gear towing rin$ (2).
thie location is not ●ccessible, then connect
grounding
cable to
main gear tiedown ring (typical ●lternate erounding point).
c. If using fuel truck. ●ttach ito 8roundin8 cable to ● certified static
d. Connect fuel truck bonding cable to noot ~ear towing ring (4).
●.
When fueling/defueling evolution haa been completed, wait ● minimum
of 2 min before
removing bondins cable.
f. TO remove grounding or bonding cables reverse ●bove procedures.
a.
.
2.1.37 C-1 ~
To ground C-1 ●ircraft during
maintenance ●volution in the hangar, proceed am follows (ser figure 2-32):
a.
b.
c.
Attach grounding cable with F183413-1 electrical ground connector
Connect free ●nd of grounding cable to nose gear towing ring (2).
this location is not acceesible~ then connect 8rounding cable to
main gear tiedown ring (typical alternatr 8rOUndin8 pOint).
43
If
——
MIL-HDBK-274(AS)
1 November 1983
.
)
I
44
\
i
LANOING
NOSE
GEAR
iND GREASE
WARNING
Bf USEO TO GROUNO AIRCRAFT.
MUST BE USED
\/
FIGURE 2-30.
,
cERTIFIED GROUND
OR
PADE YE
(LESS THAN 10.~
oH~)
($)
cAUTlal
TIE ~
RI*
MUST SE fREE OF
PAINT ANO COn moW
131
CONNECTOR
TYPICAL
ALTERNATE
GROUNDING
POINT USING
cONNECTOR
——..——
———————
MIL-HDBK-274(AS)
1 Novmber
1983
)
I
46
MIL-HDBK-274(AS )
1 November 1983
47
?IIL-HDBK-274(A8)
1 November 1983
.
c-l ~e
~
●volution on the ●pron with
~
TO ground C-1 aircraft when in themaintenanct
MEPP plugged into aircraft,
proceed as follows (see fi8ure 2-33):
2.1.38
●
.
(cl-p type) to ● c~rtified ctatic ground or padeyc (l).
NOTE:
b.
d.
●.
●n
●lectrically-driven type, then
●
power ground
Connect free ●nd of grounding cable to the nOOe gear towing ring
If this location ia not accessible, then connect grounding
(2).
cable to main gear tiedown ring (typical ●lternate grounding
point).
NOTE:
c.
If the ~PP is
must be used,
If the MEPp i- ● dieeel engine-driven
bonding requirement is waived.
type,
then
the following
nose gear towing ring (3).
Connect frpe end of bonding cable to a b-re metal ● rea on tti~MEPP
(4).
To remove grounding or bonding cable, reverse ●bove procedures.
.
2.1.39 ~
●volition. proceed as follows (see figure
2-34):
●.
b.
c.
d.
(clamp type) to a certified static ground or padeyc (l).
Connect free ●nd of grounding cable to forward fuoelage grounding
rece.ptmcle (2).
If grounding receptacle is not ●ccessible. then using ● grounding
cable with M83413-1 ●lectrical gr~nd coan~ctor ●t ●ach ●nd. follow
step ● , ●nd connect free end of grounding cable to main wheel well
door (typical alternate grounding point).
To remov~ grounding cable, reverse ●bove procedures.
2.1.40 $-170 ~
fueling or defueling, proc~ed
●
.
b.
c*
d.
●.
f.
8“
.
●s
.
To ground C-130 ●ircraft
follows (oee figure 2-35):
when
Attach groundin8 cable with M83413-1 electrical ground connector
(clamp type) to ● certified static ground or padeye (l).
Connect free ●nd of grounding cable to forward fuselage grounding
receptacle (2).
If grounding receptacle is not ●cceaoible, then using a grounding
cable with M83413-1 electrical ground connector at ●ach end. follow
step ● . ●nd connect free ●nd of grounding cable to main wheel well
If using fuel truck, attach ito grounding cable to a certified 8tatic
ground or p~deye (3).
Connect fuel truck bonding cable to main wheel well door (4).
When fueling/defueling evolution has been completed, wit a minimum
To remove bonding or grounding cable, reveree ●bove procedures.
48
)
MIL-HDBK-274(AS)
1 November 1983
k
49
—
——
MIL-HDBK-274(AS)
1 November 1983
)
50
MIL-HDBK-274(AS)
1 Nowmber
1983
.
.1
i
51
MIL-EDBK-274(AS)
1 November 1983
2.1.41 s-130~
during maintenance
a.
b.
c.
d.
.
.
To ground C-130 aircraft
in the hangar, proceed aa follows (see figure 2-36):
)
Connect free end of grounding cable to the forward fuselage grounding
receptacle (2).
If grounding receptacle is not accessible, then using a grounding
cable with M83413-1 electrical ground connector at ●ach ●d, follw
step a, and connect free end of grounding cable to main wheel well
door (typical ●lternat~ grounding point).
TO remove
grounding cable, reverse above procedures.
.
.
.
.
j%130 ~
(w~o
~
~
TO ground C-130 aircraft when in the maintenance evolution on the apron
with MEPP plugged into aircraft, proceed aE follows (ace figure 2-37):
2.1.42
a.
grounding
cable with M83413-1 electrical ground connector
Attach
NOTE :
must be used.
e.
Connect free ●nd of grounding cable to forward fuselage grounding
receptacle (2).
using a grounding
If grounding receptacle is not accessible. then
cable with M83413-1 electrical ground connector at each ends follow
step a, and connect free ●nd of grounding cable to main wheel well
to
Attach bonding cable with M83413-1 electrical ground connector
main wheel well door (3).
f.
(4).
b.
c.
d.
.
2.1.43 ~-l?O~
follows (ace figure 2-37):
a.
b.
c.
d.
e,
f.
.
.
To ground C-X30
evolution on the apron using FLEDS. proceed aa
Connect free end of grounding cable to forward fueelage grounding
receptacle (2).
If grounding receptacle is not accessible, then using a groundiag
cable with a M83413-1 ●lectrical ground connector at each endo
follow step a, and connect free end of grounding cable to main wheel
main wheel well door (3).
Connect free end of bonding cable to a bar~ metal area on the DBA
such as the stud or bolt (4) (see figure 2-155).
To remove grounding or bonding cable, reveree above procedures.
52
I
MIL-HDBK-274(A6)
1 Nowmber 1983
53
MIL-?IDBIC-274(AS)
1 November 1983
\
\
L1
n
L-J-+
J-Pa /
/
2
v
z
/
w
:&-’
‘X-AI
7
\
k
.
r-
m
A
M
54
MIL-BDBK-274(AS )
1 Novmber
1983
2,1.44 Q1-53
To ground CH-53 aircraft when in the parked
evolution, proceed as follows (see figure 2-38):
a.
b.
c.
d.
(clamp-type) t; a certified static ground or pa~eye (1).
Connect free end of grounding cable to left rear fuselage grounding
receptacle (2).
If grounding receptacle is not accessible, then using a gr~nding
cable with !483413-1 electrical ground connector at each end. follw
step a, and connect
frpe end of grounding cable to main gear static
drag wire (typical alternate grounding point).
2.1.45 QH-5?
To ground CR-53 aircraft when
fueling or defueling. proceed as follows (see figure 2-39):
a.
b.
c.
d.
e.
f.
s“
receptacle (2).
cable with X83413-1 electrical ground connector at each ●nd, follow
step a, and connect free end of grounding cable to main gear static
Connect fuel truck bonding cable to static drag wire (4).
When fuelingfdefueling evolution has been completed, wait a minimum
To remove bonding or grounding cable, reverse
above procedures.
2.1.46 ~-based
during maintenance
a.
b.
c.
d.
.
P e~
in the hangar, proceed as follws
To ground CE1-53 aircraft
(see figure 2-40):
Attach grounding cable with M’83413-1 electrical ground connector
receptacle (2).
If grounding receptacle is not accessible+ then using a grounding
cable with M83413-1 electrical ground connector at each ●nds follow
step a? and connect free ●nd of grounding cable to main gear static
.
.
.
~
~
TO ground CH-S3 aircraft when in the maintenance ●volution on the apron
with MEPP plugged into aircraft, proceed as follows (see fiBure 2-41):
2.1.47
a.
NOTE :
If the MEPP ia an electrically-driven
must be used.
55
type~
then a Power ground
HIL-EDBK-2?4(A8 )
1 190vmber 1983
R
56
MIL-HDBK-274(AS)
1 November 1983
—
.,.-.
‘n
57
FIGURE 2-40.
~d CE-53
CAUTION
EARTH GROUNOING POINT
MUST BE FREE OF
PAINT AND CORROSION
/(/
..
\
TYPICAL
/
ALTERNATE GROUNOING
v
‘\
MIL-HDBK-274(AS)
1 November 1983
u
59
MIL-BDBR-274(AS)
1 November 1983
b.
c.
d.
e.
f.
receptacle (2)s
cable with M83413-1 ●lectrical ground connector ● t each ●ndo follow
step am and connect free end of grounding cable to main gear #tatic
Attach bonding cable with M83413-1 ●lectrical ground connector to
static drag wire (3).
(4).
To ranove grounding or bonding cable, reveree ●bove procedures.
.
2.1.48 B-53 ~~
●
,
b.
c.
d.
●.
f.
.
To ground CR-53
●volution on the ●pron using FLEDS, proceeed ● o
IW~
Attach grounding cable with ?S83413-1 electrical ground conn?ctor
Connect free end of grounding cable to the left rear fua?lage
grounding receptacle (2).
cable with M83413-1 ●lectrical ground connector at ●ach end, follow
step a, and connect free end of grounding cable to main gear static
static drag wire (3).
euch as the stud or bolt (4) (see figure 2-155).
.
.
2.1.49 j&5? a~
To ground CH-53 aircraft
during stores loading or unloading, proceed as follows (see figure 2-42):
a.
b.
c.
d.
end of grounding cable to the left rear fuselage
Connect free
grounding receptacle (2).
If grounding receptacle is not acceaaible, then using a grounding
cable with H83413-1 electrical ground connector ● t ●ach end, follow
step ● . ●nd connect free ●nd of grounding cable to main gear ntatic
.
2.1.50 X-2 IUXILC$ c~
To ground E-2 aircraft when in the parked
●volition, proceed aa follows (see figure 2-43):
a.
b.
c.
Attach grounding cable with H83413-1 electrical ground connector
Connect free end of grounding cable to main gear tiedown ring (2).
If thio location is not ●ccessible, then connect grounding cable to
drag brace on the nose 8ear (typical alternate grounding point).
To remove grounding cable, reverse above procedure.
60
)
.
HIL-HDBK-274(M)
1 Nowmber
1983
n
i
h.)
u!
—_
M83413 1.
-+
-
j
/\
2
o
CAUTION
TIE OOWN RING MuST BE FREE
OF PAINT AND CORROSION
GROUNDING CASLE - ‘
CONNECT TO
TIE ObWN RING
—.
=—
FIGURE 2-43.
E-2 ~d
~AUTION
EARTH GROUNO POINT
MUST BE FREE OF
PAINT AND CORROSION
CERTIFIED GROUND
OR
PADEYE
(LESS TI-IAN 10.0000HMSI
o1
P
-J /
●
•~
.
NOSE GEAR
LOOKING FOREWARD
WARNING
BE uSED TO GROUND AIRcRAFT.
MuST E4EUSED
,,. ,,,
-x
l-l
MIL-EDBK-274(AS)
1 November 1983
2.1.51 ~
defueling, proceed as follws
a.
b.
c.
d.
e.
f.
.
.
ev~
To ground E-2 ●ircraft when fueling or
(see figure 2-44):
Attach grounding cable with M83413-1 ~l?ctrical ground conn~cto?
(clamp type) to a certified atstic ground or padeye (1).
Connect free end of grounding cable to main gear ti~down ring (2).
If this location is not accessible, then cortnect grounding cable to
drag brace on the nos~ gear (typical ●lternate grounding point).
Connect fuel truck bonding cable to main Scar tiedovn Yin8 (4).
When fueling/defueling evolution has been completed, vait a miniof 2 min before removing bonding cable.
To remmve grounding or bonding cable, reverse ●bove procedures.
.
2.1.52 ~ed
~
To ground E-2 aircraft
during
maintenance evolution in the hangar, proceed as follows (see fi~re 2-45)~
●
a.
b.
c.
Attach grounding cable with M&3413-1 electrical ground conn@ctor
If this location is not accessible, then connect grounding cable to
drag brace on the nose gear (typical alternat~ grounding point).
.
.
.
E-2 ~
@vo~
~
TO ground E-2 aircraft when in the maintenance ●volution on the apron
with MEPP plugged into aircraft, proceed as follows (see figure 2-46):
2.1.53
a.
Attach grounding cable with MB3413-1 electrical ground connector
NOTE :
b.
c.
d.
e.
must be uBed.
b.
ground
If this location ia not accessible. then connect
grounding
cable
to
drag brace on the nose gear (typical alternate grounding point).
gear tiedown ring (3).
Connect free ●nd of bonding cable to a bare metal”area on the MEPP
(4).
2.1.54
E-2 ~P
a.
type, then a pwer
.
.
To ground E-2
●volution on the apron using FLEDS, proceed as
W~
If this location ia not accessible, then connect
woundin&
cable
to
drag brace on the nose gear (typical alternate grounding Point)*
63
\
(
/
<~~
;;..
Y
FIGURE 2-44.
‘----------”
TIE OOWN EEING MUST BE FREE
OF PAINT ANO CORROSION
CAUTEON
M834131
CONNEC
///@~q\
RE(CEPTACLE
,y$~y
~
PRESSURE
FUELING
HOSE
/
/
.77’
-
Z-2 ~
l’=
r)
/
.
.
!
v
\\\
&--
TRUCK
CABI E
A
.
AG
FllFl
GROUNDiN~
GROUNDING CABLE OR
PAOEYE
[LESS THAN 10.0L30OHMS)
EONDING CABLE
-Y
1
~
~
10OKC=
+
@/D
nwcAL”
y-
.
mD
CAIILE
AIRCRAF 1.
GROUMWMC
GEAR
FORWARD
-OE
SEPARATE
lw~wmwml
= -O TO GRtXmO
ALTERUAT? G~
mmT UsmG ~cma
\. 7
●
II
I
CAUTION
EARTH GROUND POINT
E
MUST BE FREE OF
PAINT AND CORRO!jl~
---m
r
n
65
.
MIL-HDBK-274(M)
1 Novemb~r 1983
.
.
.
.
-4
I
Lb
I
66
MIL-HDBK-274(A8)
1 November 1983
c.
d,
e.
Attach bonding cable with M83413-1 el~ctrical ground connector to
main gear tideown ring (3).
Connect free ●nd of bonding cable to a bare metal ● rea 011 the DBA
such as the etud or bolt (4) (see figure 2-155).
To ranove grounding or .bondine cables r@ver~~ above procedures-
.
2,1.55
&A-6~
To ground EA-6 aircraft when in the parked
evolution, proceed as follows (se? figure 2-47):
●.
b.
c.
If this
Connect free end of grounding cable to tail bumper (2).
location is not accessible~ then connect grounding cable to bracket
inside nose wheel well (typical alternate grounding point).
To remove grounding cables reverse above procedure.
.
.
To ground EA-6 aircraft when fueling
2.1.56 M-6 ~~v~
or defueling, proceed as follows (see figure 2-48):
a.
b.
c.
d.
●.
f.
Connect free end of grounding cable to tail bumper (2). If thi6
location is not acceasibleb then connect 8r~unding cable to bracket
Connect fuel truck bonding cable to bracket inside nose wheel well (4).
When fueling/defueling evolution has be?n completed, wait a minimum
TO rmnove grounding or bonding cable, reverse above procedures”
2.1.57 M-6 ~
maintenance evolution in the hangar,
●.
b.
c,
To ground EA-6 aircraft during
proceed aB follows (eee figure 2-49):
Connect free end of grounding cable to tail bumper (2)0 If this
location is not accessible, then connect grounding cable to bracket
grounding point),
inside nose wheel well (typical ●lternate
TO r~ove grounding cable, reverse ●bove procedure-s
2.1.58 U-6 ~evo~
~
To ground EA-6 aircraft when in the maintenance evolution on the apron
with MEPP plugged into ●ircraft, proceed as follows (s*? figure 2-50):
a,
Attach grounding cable with M83413-1 electrical ground conn?ctor
(clamp type) to a certified etatic ground or padeye (1).
NOTE :
b.
If the MEPP is an ●lectrically-driven
mutt be used.
tyPe. then a Power Bround
If this
Connect free end of grounding cable to tail bumper (2).
location is not ●ccessible, then
connect
grounding
cable
to
bracket
67
.—
—– –——
MIL-liDBK-274(As)
1 Novmber 1983
R
.
3
)
t
68
MIL”HDBK-274(AS)
1 November 1983
69
MIL-EDBK-274(AS )
1 November 1983
t
I
70
/A
/’”
-----
P
me
w–
w=;-’
2?=5
~\
FIGURE 2-50.
ExTE RNAL POWER
RECEPTACLE
‘J~:~?i::xo&””
\
CONNECT TO
TAIL BUMPER
\
rMITION
-------EARTH GRoUND pOINT
MUST BE FREE oF
PAINT AND CORRO$loN
/
TAIL BuMPER
o \ GROUND)NG POINT
//:
:_..
---
\
“w
—
‘%r———
NC
6A
\T----w /
wARNING
BE USED TO GROUNOAIRCRAFT.
MUST BE USED
-
BoNOING CABLEcoNNECT TO ORACKET
IN NOSE WHEEL WELL
H
t-x
MIL-HDBX-274(AS)
1 November 1983
d.
Attach bonding cable with l@3413-1 ●lpctrical ground connector to
bracket inside nose whml well (3).
Connect free end of bonding cable to ~ bar? met~l er~a on th~ KEPP
c.
To remove
c.
(4)0
groundins or bonding cable, reverse ●bove procedures.
2.1.59
M-6 ~
aircraft when in the maintcnanc~
follmm
(oee fisure
2-50):
●
.
b,
C.
d.
e.
●volution
os
the
To Bround BA-6
apron ucin~ ?LEM, proceed ● s
Attach groundinB cable with HB3413-1 ●lectrical ground
connector
static Bround or padeyc (l).
(clamp type) to ● certifhd
bump~r (2). If this
Connect free end Of grouu~ing cable to tail
location
ic not ●ccessible, then connect grounding cable to bracket
Attach bonding cable with
M83413-1 el~ctrical ground connector to
bracket inside nose wheel well (3).
Connect free end of bondi~g cable to ● bare metal ● rea on the DBA
such as the stud or bolt (4) (se? figure 2-155).
TO remove
grounding
or
bonding cable, rev~rse above procedure.
To ground U-6 aircraft
during stores loading or unloading, proceed as foll~s
(see figure 2-51):
a.
b.
c.
Attach grounding cable with MB3413-1 electrical ground connector
Connect free ●nd of grounding cable to tail bumper (2). If this
location ie not ●ccessible, then connect grounding cable to bracket
inside nose wheel well (typical ●lternate grounding point).
To renove grounding cable, reverse above procedure.
2.1.61 F-4 ~
To ground F-4 aircraft when in the parked
a.
b.
C.
d.
Connect free end of grounding cable to engin~ nacelle grounding receptacle (typical) (2).
If grounding receptacles are not ●ccessible. then uming a grounding
cable with M83413-1 ~lcctrical ground connector at ●ach end, follow
etep a, and connect fre? ●nd of grounding cable to main gear tiedovn
To r~ove grounding cable, reveroe above procedures.
.
To ground F-4 aircraft when fueling
2.1.62 F-4 ~
defueling, proceed as follows (see figure 2-53):
a.
b.
Attach grounding
(clamp type) to
Connect free end
tacle (typical)
or
a certified 6tatic ground or padeye (l).
of grounding cable to engine nacelle grounding recep(2)0
72
?IfIL-EDBK-274(AS
)
I t]ovember 1983
●
d
m
h
73
T)
\
~
=
~
I
o
~
N
.
GROUNDING CABLE CONNECT TO
GROUNOING RECEPTACLE
ON ENGINE NACELLE
.
MUST BE USED
WARMING
J&l
II
cERTIFIED GROUNE)
on
PAOEYE
ILESS THAN IO,CODOHMSI
FIGURE 2-52.
CAUTION
EARTH GROUND POINT
MUST BE FREE OF
PAINT ANIJ CORROWON
CAUTNIN
TIE DCMN RING
MUST EIE FREE OF
PAINT AND CORROSION\
\)
TYPICAL
Al TERNATE
GROUNDING POINT
USING CONNECTOR
M133413 1
CONNECTOR
MAIN GEAR
!/-”
-
wARNING
BE USEO TO GR~O
AIRCRAFT.
SEPARATE GROUNDIm
CAIILE
-1
BE USED
~OING
CABLE ~cI
TO MAIN
IANDING GEAR
TIE DOWN RING
MuST BE FREE OF
PAINT ANO CORROSION
au?-
id
xw%y?w’~,
TYPICAL
At TERNATE
FUELING
HOSE
4
o
GROUWO
CAuTlm
-
MU5TEJEFREE~
PAINT AND CXJR~
EANTH
\
GROUNDING CABLE CONNECT TO GROUNOI*
nEmPTACLE ON ENGINE
NACELLE
MIL-HDBK-274(AS )
1 November 1983
c.
cable with M83413-I ●lectrical ground connector at ●ach end, follow
step ● , and connect free end of grounding cable to main gear tiedown
If using fuel truck, attach ite grounding cable to a certified static
Connect fuel truck bonding cable to main gear ti-down ring (4).
When fueling/defuellng ●olution has been completed, wait a minimum
d.
Q.
f.
S.
maintenance
To ground F-4 aircraft during
in the hangar, proceed as follows (see figure 2-54):
●.
b.
c,
d.
Attach grounding cable with ?i83413-1 ●lectrical ground connector
Connect free end of grounding cable to engine nacelle grounding receptacle (typical) (2).
If grounding receptacles ar~ not accessible, then using a grounding
step a. and connect free end of grounding cable to main gear tiedown
To remove grounding cable, revertae above procedures.
.
.
.
.
~-4~
~
TO ground F-4 aircraft when in the maintenance evolution orI the apron with
XEPP plugged into aircraft, proceed as follows (see figure 2-55):
2.1.64
a.
Attach grounding cable with M83413-1 electrical ground f~t,nector
(clamp type) to a certified static ground or padeye
1
NOTE :
b.
c,
d.
e.
f.
If the KEPP is an electrically-driven
muet be used.
type. then a power ground
Connect free ●nd of grounding cable to engine nacelle grounding receptacle (typical) (2).
cable with M83413-1 ●lectrical ground connector at each end, follow
step ● , and connect free ●nd of grounding cable to main gear tiedown
main gear tiedown ring (3).
Connect free end of bonding cable to a bare metal ● rea on the HEPP
(4).
To remove grounding or bonding cable, reveree above procedures.
76
)
MIL-HDBK-274(A8 )
1 Novmber
1983
77
——
MIL-KDBK-274(M)
1 Novmber 1983
+W
z
u
z
●
a-
MIL-KDBK-274(AS)
1 November 1983
2.1.65 F-4 ~ce
aircraft when
in
the
maintenance
a.
b.
c.
d.
e.
f.
b.
c.
d.
evolution
.
on
.
the
To ground F-4
apron using FLEDS, proceed as
Attach grounding cable with U83413-1 electrical ground connector
using a grounding
If grounding receptacles are not accessible, then
cable with M83413-1 electrical ground connector at each ●nd, follow
step a, and connect free end of grounding cable to main gear tiedown
such as the stud or bolt (4) (ace figure 2-155).
TO rsmove grounding or bonding cable. reverse above procedures.
2.1.66 ~
stores loading or unloading
a.
evo~
To ground F-4 aircraft during—
proceed ES follows (see figure 2-56):
If grounding receptacles are not accessible. then using a grounding
cable with M83413-1 electrical ground connector at each end~ follow
step as and connect free end of grounding cable to main gear tiedown
To rmnove grounding cable. reverse above procedures.
.
2.1.67 F-14 ~
a.
b.
c.
Connect free end of grounding cable to lower torque ann pin on nose
gear (2). If thiG location is not accessible, then connect
grounding cable to nose gear tiedown ring (typical alternate
grounding point).
.
.
2.1.68 F-14 ~
e~
To ground F-14 aircraft when fueling
or defueling, proceed as follows (see figure 2-58):
a.
b.
Connect free end of grounding cable to lower torque arm pin on nose
gear (2), If this location is not accessible. then connect
grounding point).
79
.—
PIXL-EDBK-274(M)
1 Novmber
19a3
A
●
80
ML-HDBK”274(M )
1 November 1983
/
81
w
to
w=
WARNING
FIGtJRE 2-58.
1IE DOWN CNAINS CAN NOT
8[ USEO TO GF70UND AIRCRAFT
SI PARATE GROUNDING CAB1 F
MUST EYEUSEO
F-14 ~
CAHI. F
7
EARTH
.
fuP~
CERTIFIFD GROUNO
OR
PADFYF
{1 ESS THAN 10.(ti OHMs)
CA9L E
w., ...?...”
~FUELING
.
.
GROUND POINT
-1
Ilutlll
/
\
\
.
TYPICAL
ALTERNATE
GROUNDING pOINT /
USING CONNECTOR
~\\cj71R’&Aj’;
/// 1/
MIL-xDBK-274(A8)
1 November 1983
c.
d.
e.
f.
If using fuel truck, attach it~ grounding cable to a certified static
Connect fuel truck bonding cable to lower torque ● rm pin on nose
gear (4).
When fueling/defueling mrolution has been completed. wait a minimum
TO remove grounding or bonding cable, reverse above procedures.
.
.
To ground F-14 aircraft
2.1.69 F-14~
maintenance evolution in the hangaro proceed as follows (Dee fi~re 2-S9):
a.
b.
c.
during
Attach grounding cable with X83413-1 electrical ground connector
gear (2). If thi~ location is not accessible, then connect
grounding cable to nose gear tiedovn ring (typical alternate
grounding point).
TO rmove grounding cable, reverse above procedures.
.
.
.
E-14 ~Pd
~
To ground F-14 aircraft when in the maintenance evolution on the apron
with KEPP plugged into aircraft, proceed as follws
(see figure 2-60):
2.1.70
a.
Attach grounding cable with ?483413-1 electrical ground connector
NOTE: If the MEPP is an electrically-driven
must be used.
b.
c.
d,
●.
If this location is not accessible, then connect
gear (2).
grounding cable to nose gear tiedown ring (typical ●lternate
grounding point).
Attach bonding cable with X83413-1 electrical ground connector to
lower torque arm pin on nose gear (3).
Connect free end of bonding cable to a bare metal
● rea
on
the MEPP
(4).
To r~ove grounding or bonding cable, r~verse ●bove precedureo.
2.1.71 F-14~
a.
b.
c.
d.
e.
To 8round F-14
evolution on the apron Uaiw
FLED$o proceed
●s
Attach grounding cable with ?f83413-1 ●lectrical ground connector
Connect free ●nd of grounding cable to lower torque arm pin on nose
8ear (2). If this location io not accessible, then connect
grounding point).
Attach bonding cable with M83413-I electrical ground connector to
lower torque arm pin (3).
Connect free end of bonding cable to a bare metal ● rea on the MA
such as the stud or bolt (4) (se? figure 2-155).
above Proce~urQ#O
TO remove grounding or bonding cable, reverse
83
———
——
MIL-HDBK-274(AB)
1 Novemb~r 1983
I
84
XIL-8DBK-274(M)
1 Movtmber 1903
\/
MIL-HDBK-274(A8)
1 November 1983
.
.
.
2.1.72 F-14 s~
stores loading or unloading, proceed 86 follows (see figure 2-61):
a.
b.
Connect free end of grounding cable to lower torque arm pin on none
gear (2). If this location is not accessible. then connect
grounding
cable to nos? gear tiedown ring (typical
alternate
c.
To remove
grounding
point).
grounding
cables reverse above procedures.
a.
b.
c.
d.
Connect free end of grounding cable to nose wheel well grounding
(2).
receptacle (typical)
cable with H’83413-1 electrical ground connector at each end. follow
utep a. and connect free end of grounding cable to main gear tiedown
To remove grounding cable. reverse
above procedures.
2.1.74 F-19~
or defueling, proceed as follas
a.
b.
c.
d.
e.
f.
S*
b.
To ground F-18 aircraft when
(see figure 2-63):
fueling
(clamp
type)
to a certified
static
ground
or padeye
(l).
step a, and connect free end of grounding cable to main gear tiedown
If using fuel truck. attach ite grounding cable to a certified static
Connect fuel truck bonding cable to main gear tiedovn ring (4).
of 2 ruin before removing bonding cable.
2.1.75 F-18 ~
maintenance in the hangar,
a.
.
I
grounding cable with M83413-1 electrical ground connector
Connect
free end of grounding cable to nose wheel well grounding
receptacle (typical) (2),
Attach
I
86
MIL-EDBK-274(AS)
1 November 1983
-<
—___
___
...“J
—.——-——
dili
&m
87
—
MIL-HDBx-274(A6)
1 November 1983
)
.
I
.
I
*“w
MIL-HDBK-274(AS)
1 November 1983
fl
1! ‘+-m
‘i
\
89
——
ItxL-EDBX-274(AS)
1 Movember 1983
.
)
.
.
90
MIL-HDBR-274(AS)
1 November 1983
c.
d.
If grounding
receptacles
are not accessible,
then using a grounding
cable with M83413-1 electrical
ground connpctor
at each end, follow
step a, and connect free end of grounding
cable to main gear tiedown
ring (typical
alternate
grounding
point).
To remove grounding
cable,
reverse
above procedures.
ed
F-18
TO ground F-18 aircraft
MEPP plugged into aircraft,
2.1.76
~
with
a.
c.
d.
●.
i.
2.1,77
●ircraft
follows
b.
c.
d.
e.
f.
2.1.78
1-18
stores
loading
a.
b.
evolution
on the
figure
2-65):
apron
M83413-1 electrical
ground connector
static
ground or padeye (l).
If the KEPP is an electrically-driven
must be ueed.
type,
then
a power ground
cable to nose wheel well grounding
receptacle
(typical)
(2).
If grounding
receptacles
are not accessible,
ground connector
at esch endb follow
step a, and connect free ●nd of grounding
ring (typical
alternate
grounding
point).
Attach bonding cable with X83413-1 electrical
ground connector
to
Connect free ●nd of bonding cable to a bare metal ares on the MEPP
(4).
To remove grounding
or bonding cable.
reverse
above procedures.
F-18
when in the maintenance
(see figure
2-65):
a.
.
.
(w~
_
proceed as fOl10W6 (see
●vo
Attach grounding
cable with
(clamp type) to a certified
NOTE:
b.
.
evolution
.
(us~
on the apron
using
To ground F-18
FLEDSO proceed as
Attach grounding
cable with 1483413-1 electrical
ground connector
static
receptacle
(typical)
(2)0
If grounding
receptacles
are not accessible,
cable with P183413-1 electrical
ground connector
at each end, follow
ring (typical
alternate
grounding
point).
Attach bonding cable with k183413-1 electrical
ground connector
to
Connect free end of bonding cable to a bar~ metal area on the DBA
such as the stud or bolt (4) (see figure
2-155).
To remove grounding
or bonding cable,
reverse
above procedures.
or unloading,
proceed
as follows
(see
To ground F-18
figure
2-66):
aircraft
during
Attach grounding
csble with M83413-1 electrical
ground connector
static
receptacle
(typical)
(2).
91
MIL-EDBK-274(AS)
1 November 1983
//%0
I
-11[+-%%
92
MIL-HDBK-274(As)
1 November 1983
93
MIL-EDBK-274(AS)
1 November 1983
c.
d.
2.1.79
evolution,
If grounding
receptacle
arc not accessible,
ground connector
● t ●sch ●nd,
follow
cable to main gear tierlovn
ring (typical
alternate
grounding
point).
To remove grounding
cable,
reverse
above procedures.
B-46
proceed
a.
b.
c.
as follovs
.
b.
c.
d.
●.
f.
b.
c.
with
when in the
parked
●e
follows
(see
To ground
2-68):
figure
H-46 aircraft
when fueling
Attach grounding
ground connector
static
cable to left main gear tow fitting
If this location
ig not ●cceaaible,
then connect
point
(2).
grounding
cable to right main gear tow fitting
point
(typical
alternate
grounding
point).
If using fuel truck,
attach
its grounding
cable to a certified
mtatic
Connect fuel truck bonding cable to left main gear tow fitting
point
(4).
When fueling/defueling
evolution
han been completed,
wait a minimum
of 2 min before r~oving
bonding cable.
To remove grounding
or bonding cable,
rever8e above procedure.
2.1.81
B-46
msintmance
evolution
a.
To ground R-46 aircraft
fiBure 2-67):
Attach grounding
cable with M83413-1 el~ctrical
ground connector
mtatic ground or padey~ (l).
If this location
is not accessible,
then connect
point
(2).
grounding
point
(typical
alternate
grounding
point).
To r~ove
grounding
cable,
reveree
above procedure.
2.1.80
II-46
or defueling.
proceed
●
(see
in the hangaro
proceed
To ground H-46 aircraft
as follws
(see figure
2-69).
during
Attach grounding
ground connector
power ground (l).
If this
location
is not acceaaible,
then connect
point
(2).
grounding
point
(typical
alternate
grounding
point).
To ranove grounding
cable,
reverse
above procedures.
.
.
(with
~
To 8round H-46 aircraft
evolution
on the
HEPP plugged into aircraft.
proceed as follows
(see figure
2-70):
a.
Attach grounding
cable vith
NOTE :
M83413-1 electrical
ground connector
trtatic
“must be ueed.
94
apron
type,
then
a pover
ground
)
MIL-HDBK-274(AS)
1 Novmber 1983
95
FIGURE 2-68.
0-46
wAfTaim
~
SE U$EO
TIE CHA!US MN NOT
BE -D
TO GRCJUNO AIRCRAFT<
SEPARATE GROUM)IMG CABLE
S031
m
UIL-RDBK-274(AS)
1 November 1983
97
L—
CAFJLE
FXT PWR SOURCE
FIGURE 2-70,
MAIN ALIGHTING GEAR
TOW f ITTING GROUNOING
POINT (TYPICAL E30THSIO[S)
E-46
.
MUST BE FREE OF
PAINT ANL) coRROSION
(LE&:~:::xt%&s,\
..
~[&+i::,%::A
-
—
w%”
-+-~
‘FppORFL~&:E
NC 8A
)
//’~;KEARTC,,,,LJpolN,
WARNING
BE USED TO GROUND AIRCRAf T.
SFPARATE GROUNOING CAIFLF
MUST BE USEO
.
xIL-HDBK-274(AS)
1 Novmuber 1983
b.
c,
d.
e.
2.1.83
aircraft
follows
.
H-46 ~
(see figure
2-70):
a.
b.
c.
d.
e.
2.1.84
~
stores
loading
a.
b.
c.
2.1.85
evolution,
Connect free end of
If this
point
(2).
grounding
cable to
alternate
grounding
Attsch bonding cable
left main gear tow
Connect free end of
(4).
To remove grounding
b.
c.
d.
or bonding
“~
evolution
cables
reverse
.
on the
apron
using
above
procedures.
To ground H-46
FLEDS* proceed
as
Attach grounding
ground connector
static
point
(2).
If thie location
is not accessible,
then connect
grounding
point (typical
alternate
grounding
point).
Attach bonding cable with M83413-1 electrical
ground connector
to
left main gear tow fitting
point
(3).
2-155).
TO r~ove
grounding
or bonding cables
reverse
above procedures.
.
or unloading,
proceed
as follows
(see
To ground H-46 aircraft
figure
2-71):
during
Attach grounding
cable with 1183413-1 ●lectrical
ground connector
static
If this location
is not accessible
then connect
point (2)0
grounding
cable to right
main gear tow fitting
point
(typical
alternate
grounding
point),
To remove grounding
cable,
reverse
above procedures.
OV-10 -d
proceed
a.
grounding
location
is not accessible,
then connect
right main gear tow fitting
point (typical
point).
with M83413-1 electrical
ground connector
to
fitting
point
(3).
bonding cable to a bare metal area on the lfEPP
P~
● s follows
.
(see
To ground OV-10 aircraft
figure
2-72):
when in the
parked
Attach grounding
ground connector
(clamp type) to e certified
static
cable to fuselage
grounding
receptacle
(typical)
(2).
If grounding
receptacles
are not acceaaible,
cable with a M83413-1 ●lectrical
ground connector
● t ● ach endt
follow step ● , ●nd connect free ●nd of grounding
cable to nose gear
tiedown ring (typical
alternate
grounding
point),
To rmnove grounding
cable,
reverse
above procedures,
99
.——
HIL-EDBK-274(AS)
1 ?fovcmber 1983
)
100
1
MIL-EDBK-274(AS )
1 November 1983
MIL-HDBK-274(As)
1 November 1983
.
.
2.1.86
QJ!-10 ~
fueling
or defueling,
t.
b.
c.
d.
●.
f.
e-
b.
c.
d.
as follows
(ace
figure
2-73):
when
Attach grounding
ground conn~ctor
static
ground or padeye (X).
cable to fuselage
grounding
receptacle
(typical)
(2).
If grounding
receptacle
● re not
●ccessible,
then wing ● grounding
cable with a M83413-1 electrical
ground connector
● t ●ach end,
follow step ● . ●nd connect free ●nd of grounding
cable to nos~ gear
●lternate
grounding
point).
If using fuel truck.
attach
its grounding
cable to ● certified
mtatic
evolution
has been completed.
wait ● mininum
of 2 min before r=oving
bonding cable.
To remwe grounding
or bonding cable,
reverse
above procedures.
.
.
2.1.87
U-10 ~
during maintenance
a.
proceed
.
f?VD~
in the
hangar.
proceed
ae follws
To ground OV-10 ●ircraft
(tee figure
2-74):
Attach grounding
cable with P183413-1 electrical
ground connector
power ground (1).
Connect free ●nd of grounding
cable to fuselage
grounding
receptacle
(typical)
(2).
If grounding
receptacles
are not accessible,
ground connector
st ●ach end, follow
step a, and connect
free end of grounding
cable to nooe gear tiedown
ring (typical
alternate
grounding
point).
To remove grounding
cable.
reverse
above procedures.
.
.
.
.
2.1.88
QY-10 ~
evolution
on the
dK.SX@&
with ?tEPP plugged into aircraft,
proceed aR follows
(see figure
2-75):
a.
)
Attach grounding
cable with
NOTE:
If
apron
M83413-1 ●lectrical
ground connector
static
tbe tlEPP is an ●lectrically-driven
be used.
type.
then
●
power ground
must
b.
c.
cable to fumelage grounding
receptacle
(typical)
(2).
If grounding
rec~ptacles
are not accessible,
ground connector
at each end- follow
cable to noee gear tiedown
ring (typical
alternate
grounding
point).
NOTE:
d.
If the MEPP is a dieoel engine-driven
bonding requirement
is waived.
Attach bonding cable with M83413-1
102
type.
electrical
then
ground
the
follwing
connector
to
I
“-==ww
FIGURE 2-73.
FUEL FILLER
CAPS
FUEL TRUCK
{~=,
FUELING
HOSE
A
~
o1
VJ
‘ ~,&J-
“m
U(
(0
‘<J
./+
c’
./
‘m-,2)
/
CONNf CTOR
CAUTION
)
“3
TIE DCWN RING
MUST BE FREE OF
PAINT ANO cORROSION
TYPICAL
At TERNATE
GROUNDING pOINT
uslNG CONNECTOR
‘$
/
‘1
VM834131
NOSE GEAR
/-’-’-7+ --
CAUTION
EARTH GROUND POINT
MUST BE FREE OF
PAINT ANO CORROSION
GRouNDING CABLE CONNECT TO
FuSELAGE GROUNDING
RECEPTACLE
-jr’
CERTIFIED GROUNO
OR
PADEYE
(LESS THAN 10.OCH3OHMSI
‘t
o3
BONDING
CABLE
4
0
P
GROUNDING
RECEPTACLES
WARNING
TIE DOWN CHAINS CAN NO?
BE USED TO GROLJND AIRCRAFT.
MUST BE USED
M331C4
XIL-HDBK-274(M)
1 Novmb~r 1983
.
.
.
.
0
I
o
7
1
u“
iA
104
llcQIJl
I Allu
Ov
ELECTRICAL
10’
l~\*””**”#I
~lTILITY
PAlm
-R
FIGURE 2-75.
Ov-loo
\
I
I
1
(.tJ?I n,.mlum
CAUTION
~
TIE OOWN RING
MUST BE FREE OF
. . .. . . --. ..-. m*-.n .,
ExTERNAL ELECTRl~L
PnWER
.-. .— RECEPTACLE
FXTERNAL
.
1——
\
/’-’”7
.
Ov-lo ~p
AN ELECTRICALLY
TYPE
ORIVEN
ILLUSTRATIVE
PURPOSES
IT is R’OUIREO ONLY
wHEN THE MEPP M
issWwN01
TIE DOWN RING
CABLE –
---------(xJNmtLl
Iv
NOTE
THE BoNDING (OF THE
NLY FOR
/.
N
l\
[[
7/
II
- J/d
DING
BONr
/
.
o
1
POWER
cORD
REcEPTACLE
FUSE LAGE
CAUTIOU I
cARTH GROUN[ ) POINT
- ‘--MUST-BE FREE OF
O-INT
ANn CORROSION
. . . . . . . . ----
cERTIF!ED GROUND
[LESS THAN 10.OGGOH=)
v
-1=
G&RO:l)T~nLE
~
---/(#L
WARNING
SEPARATE GRWNDING
CABLE
MUST BE USED
-
MIL-HDBK-274(AS)
1 November 1983
e.
f.
Connect free end of
(4).
To remove grounding
2.1.89
9V-10 s~
during stores
loading
a.
b.
C.
d.
evolution,
b.
c.
2.1.91
defueling,
b.
C.
d.
e.
f.
or bonding
to
a bare
cable,
reverse
.
or unloading,
metal
.
$w~
proceed *S follas
area
above
on
the MEPP
procedure.
To ground OV-10 sircraft
(Bee figure
2-76):
aa
follows
To ground P-3 aircraft
(see figure
2-77):
when in the
parked
Attach grounding
ground connector
static
cable to grounding
lug on main landing
gear (2).
If this location
iG not accessible,
then connect
grounding
cable to upper part of static
drag wire (typical
alternate
grounding
point).
To remove grounding
cable,
reverse
above procedures.
J’-l ~
proceed
a.
cable
Attach grounding
cable with ~3413-1
electrical
ground connector
static
cable to fuselage
grounding
receptacle
(typical)
(2).
If grounding
receptacle
are not accenrnible,
cable with M83413-I electrical
ground connector
at ●ach ●nd. follow
etep a, and connect free end of grounding
cable to nose gear tiedown
ring (typical
alternate
grounding
point).
To remove grounding
cable,
reverse
above procedures.
proceed
a.
.
bonding
.
as follws
(see
To ground
2-78):
figure
P-3 aircraft
when fueling
or
Attach grounding
ground connector
static
cable to grounding
lug on main landing
If this location
is not accessible,
then connect
gear (2).
grounding
drag wire (typical
alternate
grounding
point).
attach
its grounding
#t&tic
Connect fuel truck bonding cable to grounding
lug (4).
evolution
has been completed.
wait a minimum
To remove grounding
or bonding cableo reverse
above procedures.
106
XIL-EDIJK-274(M)
1 November 1983
i
107
?fIL-EDBK-274(AS)
1 November 1983
+’u
)
108
.—
MIL-EiDBK-274(AS)
I November 1983
w
E
Id
k
109
.
MIL-HDBK-274(As )
1 November 1983
P-3 airframe
must be static
grounded when parked
engines
arc u6Qd to supply electrical
power for
maintenance
check or runup te8ts.
The grounding
presently
mounted on the main landing whe~ls can
upon to prevent
airframe
electrostatic
buildup.
2.1”.92
z-?
maintenance
evolution
a.
b.
c.
c.
d.
e.
2.1.94
.d,ircraft
follow~
proceed as follows
(see
Attach grounding
cable with
NOTE:
b.
b.
P-3 aircraft
during
figure
2-79):
evolution
on the
figure
2-80):
Connect free end of
gear (2).
If this
grounding
cable to
grounding
point).
Attach bo~ding cable
grounding
lug (3).
Connect free end of
(4).
To resnove grounding
apron
with
KEPP
M83413-1 electrical
ground connector
static
If the KEPP ia an electrically-driven
must be used.
.
p-? ~*
(see figure
2-80):
a.
To ground
as follwe
(see
hangars proceed
Attach grounding
cable with M83413-1 ?lectrical
ground connector
(clamp type) to a certifi~d
power ground (l).
cable to grounding
lug on main landing
If thig location
is not accessible,
then connect
gear (2).
grounding
drag
wire
(typical
alternate
grounding
point).
To remove grounding
cable,
reverse
above procedures.
2.1.93
~-?
plugged into aircraft,
a.
in the
and its
any type of
straps
not be relied
type.
then
a power ground
grounding
cable to grounding
lug on main landing
location
ia not accessible.
then connect
upper part of static
drag wire (typical
alternate
with
M83413-I
electrical
bonding
cable
to a bare
or bonding
cable,
ground
metal
reverse
.
(us~
(W?O
W
●volution
on the apron
using
area
connector
to
on the KEPP
above procedures.
To ground P-3
FLEDS, proceed as
Attach grounding
cable with X83413-I electrical
ground connector
static
cable to grounding
lug on main landing
If this
location
is not accessible,
then connect
gear (2).
grounding
drag wire (typical
alternate
grounding
point).
110
FIGURE 2-79=
/
R+
..r.
,—
GROUNo
.
EARTH GROUNO POINT
MUST BE FREE
.
\powER/
EXTERNAL
POWER
RECEPTACLE
(LESS THAN 10oHMsl
cERTIFIFD
TO
.
d P-3 a~
h
cONNFCT
/.Flo”ruE)l.bL.tJLt-/
\
“&5x
Lq-----l
‘1
MAIN
Y \\
.......
(
MEt
cONNE
+~?,;.,
\
#
11
~
MAIN
L ANOI NG
GEAR
/
NOTE:
IF GROUNOl~G LUGS COATED WITH
PAINT. CONNECT GROUNDING CABLE
TO UPPER PART OF STATIC DRAG
WIRE
!031 m
.
_—.
KIL-HDBK-274(AS)
1 November 1983
w
:
<
)
CCE
.
/ /’/
W’\/ k
.
.
.
/
1
m
I
\
I
AEil
●
k!
112
MIL-KDBK-274(AS)
1 November 1983
c.
Attach beading cable with H83413-X electrical
ground connector
to
grounding
lug (3).
2-155).
TQ remove grounding
or bonding cable.
reveree
above Procedures*
d.
e.
stores
loading/unloading,
a.
b.
c.
2.1.96
evolution,
.
proceed
b.
c.
d.
b.
c.
d.
e.
f*
g.
follows
(see
figure
2-81)s
during
8s follows
To ground S-3 aircraft
(see figure
2-82):
when
in the
parked
Attach grounding
cable with U83413-1 electrical
ground connector
static
cable to pylon grounding
receptacle
(typical)
(2).
If grounding
receptacles
are not accessible,
then using a 8rounding
cable with XS3413-1 electrical
ground connector
at each end, follow
step as and connect free end of grounding
cable to none gear tiedown
ring (typical
alternate
grounding
point).
TO remove grounding
cable,
reverse
abov~ procedures”
s-? f~
proceed
a.
●a
Attach grounding
ground connector
static
cable to grounding
lug on main landing
gear (2).
If this locution
is not acce~sible~
then connect
grounding
cable to upper part of Btatic
drag wire (typical
alternate
grounding
point).
TO r~ove
grounding
tablet
r-me
above Procedures=
~
a.
2.1.97
defueling,
proceed
ag follows
(oee
figure
To ground
2-83):
S-3 aircraft
when fueling
or
Attach grounding
ground connector
static
receptacle
(typical)
(2).
If grounding
receptacles
are not accessible.
then usin8 a grounding
cable with MS3413-1 electrical
ground connector
at ●ach ●nd, follow
step a, and connect free
end of grounding
cable to nose gear tiedm
ring
(typical
alternate
grounding
point).
If using fu~l truck,
attach
its grounding
static
Connect fuel truck bonding cable to main gear tiedovn ring (4).
evolution
has been completed,
wait a minimum
To remove grounding
or bonding cable,
reverse
above procedure.
113
..—
-- ——
HIL-HDBK-274(M )
1 November 1983
.
;
+“w
I
114
RECEPTACLE
ON PYLON
FIGURE 2-82.
A
=
\o
I
CERTIFIEO GROUND
OR
PADEVE
(LESS THAN 10.000 OHMS}
S-3 ~
CAUTION
EARTH GROUND POINT
MUST BE FREE OF ‘
PAINT AND CORROSION
CROUNOING
-------- ..-
w
‘RO”ND:f=&J&
.
.
I
WARNING
TIE DCMN CHAINS CAN NOT
BE USEO TO GROUND AIRcRAFT
SEPARATE GRWNDING
CABLE
MUST BE USED
WI!
11
\
~-? ~
SINGLE POINT
REFUELING
RECEPTACLE
FIGURE 2-83.
I I
FuEL NOZZLE
GRouND WIRE
CONNECTION
.
.
CAUTION
EARTH GROUND POINT
MUST BE FREE OF
pAINT AND CORROSION
BONDING cABLE
coNNECT TO
TIE DOWN RING
\\ \
\\ fg
.
.
evol~
.
ALTERNATE GROUNDING
TIE DOWN RING MUST BE
FREE OF PAINT AND CORROSIL)N
I
WARNING
BE USED TO GEIOUND AIHCRAFT.
MUST BE USED
MIL-EDBK-274(AS)
1 November 1983
2.1.98
$-q ~
maintenance
in the hangar,
s.
Attach
b.
(clamp
Connect
proceed
●s
(se@ figure
2-84):
follows
grounding
cable with
type) to ● certified
M83413-X electrical
power ground (l).
fr~e
end of grounding
cable
to pylon
(typical)
(2).
If grounding
r~ceptacle6
arc not ●ccessible,
ground
grounding
during
connector
receptacle
then using ● grounding
ground connector
● t ●ach ●ndb follow
step a. ●nd connect free -~ of grounding cable to nwtied~
ring (typical
●lternat~
grounding
point).
TO r~ove
grounding
cable} reverse
above procedures-
c.
d.
2.1.99
~
with
$-~ ~
TO
ground S-3 ●ircraft
vhen in the maintenance
wolution
on the
MEPP plugged into aircraft.
proceed as follows
(see fiwre
2-85)t
a.
Attach groundin8
cable with
NOTE:
b.
(typical)
c.
d.
●.
f.
free
●nd of grounding
(2).
b.
c.
d.
●,
f.
csble
type,
to pylon
then
●
grounding
power ground
receptacle
If grounding
receptacles
are not accessible.
cable vith MB3413-1 electrical
ground connector
● t ●ach ●nds follow
etep av and connect free end of grounding cable to nose gear tiedon
ring (typical
●lternate
grounding
point).
ground connector
to
Connect
free ●nd of bonding
cable to ● bar? metal ● rea on the MEPP
(4)*
TO remove grounding
or bonding cable,
reverse
●bove procedures
.
2,1.100
S-3 ~~
aircraft
foilovs
(see figure
2-85):
a.
M83413-1 electrical
ground connector
static
8round or padeye (1).
If the KEPP ia an electrically-driven
must be uocd.
Connect
apron
~~
●volution
.
on
the
apron
using
To ground S-3
FLEDSS proceed ao
grounding
cable with M83413-1 ●lectrical
ground connector
static
receptacle
(typical)
(2).
If grounding
rpceptaclee
are not ●cceaaible,
cable with MB3413-1 electrical
ground connector
● t each
●nds follow
cable to nose 8ear
tiedovn
ring (typical
alternate
grounding
point).
Attach
bonding cable with 1483413-I electrical
ground connector
to
nose gear tiedown ring (3),
2-155).
To rmove grounding
or bonding cables
reverse
above procedures.
Attach
117
c1
FIGURE 2-84.
CAUTION
EARTH GROUND POINT
MUST BE FREE OF
PAINTANOCORROSION
dS
\
~
G
CERTIFIED GROUND
(LESS THAN 100HMS)
GROUNDING CABLE
CONNECT TO
GROUNDING +
RECEPTACLE
ON PYLON
\
v
MUSTBE
CORROSION
I
ALTERNATE GROUNDING
TIEDOWNRI!JG
FREEOFPAINTANO
POWER
BLDG
EXTERNAL AC POWER
REcEPTACLE
will
89
m
w
1-
k
FIGURE 2-85.
Al TERNATE GROUNDING
FREE OF PAINT ANO CORROSION
TIE DOWN RING MUST BE
“Kh
WARNING
MUST BE USED
\
w
CERTIFIED
GROU~o
/
fi;q
CAUTION
EARTH GROUNII POINT
MUST OF FREE OF
PA IN TAND CORROSION
/
(LESS THAN 10,000 OHMS}
1
:“LE
J’kBONOtNG
EXT PWR SOURCE
“.b.nQ=,:
[7’
/
.1
.
SOJI 140
.
—.
MIL-EDBX-274(AS )
1 November 1983
2.1.101
~~g
@tore@ loadimg or unloading.
●.
c,
d.
2.1.102
evolutions
U-2
(ace
figure
2-86):
during
grounding
type)
~
proceed
●.
proceed
.
ground connector
to ● certified
static
ground or padey~ (l).
Connect
eablc to pylon grounding
receptacle
(typical)
(2)0
If grounding
receptacle
are not ●ccessible,
then using s grounding
ground conn~ctor
● t each
●nd. follow
sttp ● , ●nd connect free end of grounding
cable
to nose gear
tiedovn
ring
(typical
●lternat~
grounding
point).
To ranov~ grounding
cable,
reverse ●bove procedur~s.
Attach
(clamp
b,
•v~
● a follows
●
s follows
(see
To ground SH-2 aircraft
figure
2-87):
when in the
parked
grounding
cable with MB3413-1 ●lectrical
ground connector
type) to a certified
static
ground or padeyc (1).
Connect fr?e end of cable to front left fuselage
grounding
receptacle
(2).
If grounding
receptacle
itI not ●ccessible,
cable with !483413-1 el~ctrical
ground conn~ctor
● t ●ach end,
follow
step ● , and connect free end of grounding
cable to main 8ear
alternate
grounding
point).
To rmove grounding
cable,
reverse
●bove procedures.
Attach
(Cl-p
b,
c.
d.
2.1.103
M-2 ~
or defueling,
proceed
a.
b.
c.
d.
e.
f.
8*
b.
●e
.
follows
(see
figure
To ground
2-88):
SR-2 aircraft
when fueling
Attach grounding
cable with X83413-1 electrical
ground connector
static
cable to front
left
fucelage
grounding
receptacle
(2).
If grounding
receptacle
is not ●ccessible,
then usin8 ● grounding
ground connector
● t ●ach end,
follow
step ● - end connect free ●nd of grounding
cable to main gear
tiedown
ring (typical
●lternate
grounding
point).
attach
its grounding
static
Connect fuel truck bonding cable to maim gear tiedown ring (4).
evolution
haa been completed,
wait ● minimum
of 2 min before
removing bonding cable.
To remove grounding
or bonding cable,
reverse
●bove procedures.
2.1.104
W-2 ~
during maintenance
●.
.
.
in the
hangar,
.
proceed
as follows
To ground SH-2 aircraft
(eee figure
2-89):
Attach grounding
cable with X834X3-1 electrical
ground connector
power ground (l).
cable to front
left
fuoelage
grounding
receptacle
(2).
120
MIL-EDBK-274(A8)
1 November 1983
121
u
~NEcTfJR
FIGURE 2-87.
CAUTION
~
WARNING
TIE OCWN CHAINS CAN NOT
BE USED TO GROUND AIRc~AFT.
SEPARATE GROUNDING CA8LE
MUSTM USE Q
~-2
/
~
~
I
.
CAu-nm
EART14 GROUND POINT
MuST BE FREE OF
PAINT ANO CORROSION
.
——
..=
ILE=
—
GROUNO
on
&
PADEYE _
THAN 10,LKNIOHMii
=
CERTIFIED
GROUNDING CABLE CONMECT TO FUSELAGE
G ROUNDING RECEPTACLE
ON LEFT SIDE
@$J
o1
MIL-HD!K-274(AS)
1 Novmber 1983
●
✎
✎
✎
✎
I
123
.-
.-
PIIL-EDBK-274(A8)
1 Novmber
1983
)
I
I
124
XIL-ED2K-274(A2)
1983
1 SIovember
c,
d,
thou using
● grounding
If 8roundin& raceptoclc
is not ●ccessible.
ground conn~ctor ●t ●ach ●nds follow
csble to main gear
otep ● s ●nd connect free end of groundha
tiodown ring (typical
sltertwt?
grouadfag point).
To r~ovc
grounding
cable, rwerc~
●bwe proccdurecs
2,1,105
with
sB-2~
whom in the mai8te8attce .voltttioa
os CIIQ ●pron
To 8:ound-8H-2 ●ircraft
XEPP plugg~d into aircrmftg procoed ● s follow
(oec fisura 2-90)~
●,
grounding cablc with 2483413-1 electrical
ground corrector
(clamp type) to o certified
otatic $rouad or padoyo (1).
Attach
?IOTE8 If
the
must
MEPP is
●n
electrically-dxivert
type.
then
●
power
&round
be us-d.
e.
cable
to front
left
futelage
grounding
Connect
free ●nd of grounding
receptacle.
then using
● grounding
If grounding
receptacle
i. not ●ccessible,
ground connector
● t ●ach ●nd. follow
step •~ ●nd connect
cable
to main gear
(typical
●lternate
grounding
point).
tiedown
ring
Attach
bonding
cable with ?SS3413-1 ●lectrical
ground connector to
cable to bar~ metal ● rea on the MEPP
Connect free ●nd of boadin8
f.
(4)0
To remov~ grounding
b.
c.
d.
2.1.106
~-2 ~&#QQ_u.
●ircraft
follovo
(see figure
2-90):
a.
Attach
b.
(clamp
Connect
c.
If
d.
f.
2.1,107
stores
loading
a.
b.
●volution
cables
on the
reverse
●pron using
●bove procedures.
To ground SH-2
FLEDS. proceed ● s
(2)0
grounding
then using
● grounding
ground connector
● t ●ach ●nd.
follow
electrical
cable to main gear
(typical
●lternate
grounding
point).
receptacle
with ?S83413-1
● s ●nd connect
tiedown ring
Attach bonding
MS3413-1 electrical
ground connector
to
(3).
Connect free ●nd of bonding cable to bare metal ● rea on the DBA such
as the sutd or bolt (4) (Bee figure
2-155),
To rmnove grounding
or bonding cable,
reverse
above procedur~s.
main gear
e.
bonding
grounding
cable with MS3413-1 electrical
ground connector
type) to a certified
static
cable to front left fuselage
grounding
receptacle
cable
step
or
or unloading,
cable
tiedown
proceed
receptacle
free
as follows
(set
To 8round SH-2 aircraft
figure
2-91):
during
ground connector
ntatic
or padeye (l).
●nd of grounding
cable to front
left
fuselage
grounding
Attach
grounding
(clamp type)
to
Connect
with
ring
cable
with
a certified
(2).
125
KIL-HDBK-274(AS )
1 Nov~ber
1983
.
)
126
—
14xL-HDBK-274(AS)
1 November 1983
m
127
MIL-EDBK-274(AS)
1 November 1983
c.
If @rounding receptacle
in not ●cceaoible,
then uming a groundina
cable with ~3413-1
electrical
ground conmctor
●t each ●idj follw
stop SP ●nd coxmtct fret and of grounding cable to main gmr
tfodovn
rims (typical
●ltmmatc Sroundius point).
d.
To rmove
csble.
groundin~
procedures.
rcvers~ •bov~
To ground SI!-3 aircraft
e fi8ure
●
,
Attcch
(clap
b,
c.
2.1.109
~
or defueling,
s.
b.
c.
d.
●.
f.
when in the parlmd
2-92)I
grounding cable with
typo) to ● cmtffhd
static swundor
cable
to static
ground comwctor
pedeys (1).
dreg virc bolt (2).
Comnoct free ●nd of groundin~
If this location
then connect
groundin
cable
main gear
tiedown
ring
(typical
sltcrmatc grounding
point ! .
cable. revers~ ●bove procedures.
To remov~ grounding
To ground
proceed
●o
follows
(see
figure
SR-3 ●ircrtiftwhen fueling
2-93)!
Attach
grounding
cable with ?@3413-1
to ● certifhd
static
ground or padeyc (l).
(clamp type)
cable
to static
drag wire bolt
(2).
Connect
If this
locstion
then connect grounding
cable to
●lternete
grounding point).
main gear tiedown
ring
(typical
If u~ing fuel truck,
attach
ite grounding
cable
to ● certified
static
Connect
fuel
truck bonding
cable to main sear tiedown ring (4).
evolution
has been completed,
wait ● minimum
To remove grounding
or bonding
cable,
rwerse
●bow procedure.
To ground
during
●volution
maintenance
a.
b.
c.
to
in
the
hangar,
proceed
●s
follow
SR-3 ●ircraft
(see
figure
2-94):
Attsch
grounding
cable with M83413-1
●l~ctricsl
ground connector
(
power Sround (l).
(clamp type)
to ● certifi~d
cable
to static
drag wire bolt (2).
If this
location
then connect
grounding
cable
●lternate
grounding
point).
main gear tiedovn
ring
(typical
To r~ove
grounding
cable.
reverse
●bov~ procedures,
2.1.111
~
vith
&.H-?
To ground SI1-3 ●ircraft
when in the mintexmnce
evolution
into aircraft,
proceed as follow
(s~e figure 2-95):
MEPP plugged
to
a.
Att&ch
(clamp
NOTE :
grounding
type)
to
If the MEPP is
must be used.
cable
with
a certified
●pron
?!83413-1
●lectrical
ground connector
etatic
an ●lectrically-driven
128
on the
type,
then
●
power
ground
MXL-IIDBK-274(M )
1 Nov-ber
1983
w
m
NL-HDBX-274(AS)
1 Novtmber 1983
I
130
MIL-HDBK-274(M)
1983
1 ~ov~ber
v
131
MIL-RDBK-274(AS)
1 Nowmber 1983
:
.
ii
/
/’
.
.
.
/’
d
/
&
/
.
i’ ,,/’
F’
I
m
\
I
\ )
I
132
HIL-IfDBX-274(AB )
1 November 1983
b.
C.
Connect free ●nd of grounding csble to ctatic drag wire bolt (2).
If this
location
is not ●ccessible
then connect
tiroundi~
cable
ring (typical
●ltermte
groundirq point).
main gear tiedown
bonding
cable
gear tiedown
free end of
Attach
main
d.
C~ct
●.
To ramve
grounding
2.1.112
$H-~ ~
●ircraft
follows
(see figure
2-95):
●.
b.
c.
d.
e.
b.
c.
2.1.114
evolution,
electrical
grouad
connector
to
ceble
to
●
cable~
bar@ met*l
reverc~
● rea
●bove
.
on the
procedur~o.
To ground
●volution
on ths
●pron
using
MEPP
PLQS.
proceed
SH-3
●s
grounding
ground connector
(clamp type)
to a certified
static
ground or padeye
(l).
cable
to static
drag wire bolt
(2).
If this
location
is not accessible,
then connect
grounding
cable
to
main gear tiedown
ring (typical
alternate
grounding
point),
bonding cable with M83413-1 electrical
ground connector
to
Attach
main gear tiedown ring (3)0
Connect
free end of bonding cable
to ● bare metal ● rea on the DBA
such as the otud or bolt
(4) (oee figure
2-155).
TO ranove grounding
or bonding
cable,
rwer~e
●bove procedur~~.
or unloading.
proceed
●a
follow
To ground SE-3 sircraft
(set figure 2-96):
Attach
grounding
ground connector
static
(clamp type)
to ● ctrtifi~d
Connect
fr~e ●nd of grounding
csble
to ●tatic
drag wire
bolt
(2).
If this location
it not ●ccessible,
then connect groundin
cable
ring (typic-l
●lternate
Urounding
point ! .
main gear tiedown
rwerse
above procedures,
To remove grounding
cable.
To ~round
proceed
●s
●.
Attach
b.
(clamp
Connect
d.
bcmding
or bonding
~
c.
l@3413-1
(3).
Attach
loading
●.
vith
ring
to
follows
(see
figure
SH-60
aircraft
when
in
the
to
parked
2-97):
grounding
cable with U83413-1
otatic
type)
to ● certified
cable
●lectrical
ground connector
ground or padeye
(1).
to fuselage
grounding
receptacle
(typical)
(2).
If grounding
receptacles
● re not
●ccessible.
then using
● grounding
cable with M834X3-1 electrical
ground connector
● t each
ends follow
cable to static
drag wire
step a. and connect
(typical
●lternate
grounding
point).
To remove
grounding
cables
reverse
133
above
procedures.
MIL-HDBK-274(AS)
I Rovmber 1983
I
I
134
MIL-XDM-274(M)
] November 1983
.
.
.
0
I
135
.——.——
MIL-EDBK-274(As)
1 November 1983
2.1.115
sEiflJ
fueling
or defueling,
(typical)
(2).
If grounding
receptacles
d.
● re not
accearible,
then using
● grounding
ground connector
● t ●ach ●ndo follow
step ● , and connect free end of grounding
cable to static
drtg wire
(typical
●lternate
grounding
point).
attach
its grounding
●.
static
Connect
ground or padeye
(3).
fuel
truck bonding
cable
b.
c.
d.
with
the
hangar,
proceed
Attach
(clamp
NOTE:
b.
c,
d.
f*
grounding
type)
to
If the MEPP ia
must be used.
Connect
wire
ae
To ground
(tee
figure
follows
(4).
wait
a minimum
procedures.
SH-60 aircraft
2-99):
free
when
with
certified
the
as
maintenance
follows
M83413-1
static
grounding
cable
evolution
(Bee
figure
on the
2-1OO):
●lectrical
ground
●lectrically-driven
an
end of
in
proceed
cable
●
.
.
ground connector
or padeye
(l).
type,
to
fuselage
then
a power
grounding
8round
r~ceptacle
(typical)
(2).
If grounding
receptacles
are not accessible,
then
using
a grounding
ground connector
at ●ach ●nds follow
cable to etatic
drag wire
~tep n. and connect
(typical
alternate
grounding
point).
Attach bonding cable with ~3413-1
electrical
ground connector
to
static
e.
drag
Attach grounding
cable with PY83413-1 ●lectrical
ground connector
power ground (l).
cable to fuselage
grounding
receptacle
(typical)
(2).
If grounding
receptacle
are not accessible,
then
uoing ● grounding
ground connector
at ●ach ends follow
step ● , and connect
cable to ctatic
drag wire
(typical
alternate
grounding
point).
To remove grounding
cable,
reverne
above procedure.
.
~-ho
~~~
To ground SH-60 ●ircraft
MEPP plugged into aircraft.
●.
static
.
e~o~
in
maintenance
a.
to
evolution
has been completed.
of 2 min before resnoving bonding cable.
To remove grounding
or bonding cable,
reverse+ above
S$-60~
2.1.117
when
c.
g.
●pron
(see
b.
f.
during
so follows
Attach grounding
ground connector
(clamp type? to ● certifi~d
static
cable to fuselage
grounding
receptacle
Connect
●.
2.1.116
To ground SR-60 aircraft
figure
2-98):
@wlluiQL
proceed
drag
wire
(3).
(4).
To remove grounding
or bonding cable,
reverge above procedures.
136
)
XIL-EDBK-274(AS)
1 llovauber 19&3
137
XIL-HDBK-274(M)
1 November 1983
)
I
138
TO STUO OR
EK)LT ON D8A
TO
SERVICE
CABLE
?Icuu
ExT
POWER
CORO
2-1oo.
WAfVUING
TIE DOWN CHAINS cAN NoT
BE USED TO GROUND AIRCRAFT;
SEPARATE GROUNDlffi
CABLE
MUST BE USED
EARTH GROUNO KMNT
MUST SE FREE OF
PAINT ANO COnR~~
,
MIL-HDBK-274(AS)
1 November 1983
.
2,1.118
SIi-6D ~
aircraft
evolution
follows
(see figure
2-100);
a.
b,
C.
d.
e.
f.
during
stores
a.
b.
c,
d.
2.1.120
evolution,
b.
c.
loading
b.
c.
To ground
FLEDS, proceed
SIi-60
8S
)
or unloading,
proceed
as follms
To ground SR-60 aircraft
(see figure
2-101):
Attach grounding
ground connector
static
ground or padeye (I).
cable
to fueelage
grounding
receptacle
(typical)
(2).
If grounding
receptacles
are not acceacible,
cable with !483413-1 electrical
ground connector
step a, ●nd connect free end of grounding cable to mtatic drag wire
(typical
alternate
grounding
point).
To remove grounding
cable.
reverse
above procedures.
.
(see
To ground TU-57 aircraft
figure
2-102):
when in the
parked
Attach grounding
cable with H83413-1 electrical
ground connector
(clamp type) to ● certified
static
cable to tang on skid (2).
If this
location
then connect
grounding
cable to tw
ring (typical
alternate
grounding
point).
To remove grounding
cable,
reverse
above procedures.
2.1.121
~~
fueling
or defueling,
a.
ueing
Attach grounding
ground connector
static
Connect free end of grounding cable to fuselage
grounding
receptacle
(typicsl)
(2)0
If grounding
receptacles
● re not
accessible,
then uoing ● grounding
cable with lIY83413-1 electrical
grmnd connector
● t each ●
d,
follow
cable to static
drag wire
step a, ●nd connect free ●nd of grounding
(typical
●lternate
grounding
point).
ground connector
to
static
drag wire (3)”.
Connect free e~ of bonding cable to ● bare metal ● rea on the MA
2-155).
TO rmove grounding
or bonding cable,
reverse
●bove procedures.
D-57 ~
proceed as follows
a.
.
(~
on th~ apron
.
proceed
as follows
(see
To ground TH-57 aircraft
figure
2-103)t
when
Attach grounding
cable with ?f83413-1 ●lectrical
ground connector
static
cable to tang on ekid (2).
If this
location
is not acceecible,
then
connect
grounding
cable to tow
ring (typical
alternate
grounding
point),
attach
its grounding
etatic
I
140
MIL-HDBX-274(M)
1 November 1983
●
✎
●
●
I
141
——
MIL-HDBK-274(AS )
1 November 1983
I
142
MIL-HDBK-274(AS)
1 November 1983
143
XIL-EDBK-274(M)
1 November 1983
Connect fuel truck bonding cable to tang on skid.
When fueling/defuelin&
●volution
has been completed,
wit
● miniwm
To remove grounding
or bondin~ cable,
rwerse
●bove procedures.
d.
e.
f.
2.1.122
nmintmatice
~-s7
~
evolution
●.
hangar.
proceed
●s
follow
(see
fi.@re
Attach grounding
ground connector
power ground (1).
cable
to
tang on skid (2).
If this
location
is not accessible.
then connect
grounding
cable to tow
ring (typical
alternate
grounding
point).
To renove grounding
cable.
reverse
●bove procedures.
b.
c.
.
●ircraft
during
2-104):
To ground
in the
)
.
(~
To ground TN-57 aircraft
evolution
on the
KEPP plugged into aircraft,
proceed as follows
(see figure
2-105):
2.1.123
with
a.
Attach grounding
cable with
(clamp type) to a certifi~d
NOTE:
b.
M83413-1 electrical
ground conn?ctor
static
If the MEPP ie an electrically-driven
must be used.
type,
●ngine-driven
ia waived.
NOTE: If the MEPP in a di?sel
c.
then
cable to tang on skid
location
is not accessible,
ring (typical
alternate
grounding
point).
bonding
Attach
requirement
bonding
cable
with
d.
on skid-(3).
Connect free ●nd of bonding
●.
(4)
To remove grounding
apron
type,
N83413-1
●lectrical
cable
to a bare
then
ground
a power ground
(2).
If
this
cable
to
tow
the
following
conn?ctor
to
tang
metal
● rea
on the MEPP
●
2,1.124
swolutiont
W-12
~
proceed
a.
b.
c.
follows
(see
cable~
rtveroe
To ground UC-12 ●ircraft
figure
2-106):
above procedures.
when
in the
parked
Attach grounding
cable with H83413-X ●lectrical
ground connector
(clmmp type) to a cercifi~d
static
cable to nose wheel axle (2).
If this
location
is not accessible,
cable to main
wheel axle (typical
alternate
grounding
point).
To remove grounding
cable,
reverse
above procedure.
2.1.125
~
fueling
or defueling,
a.
•V~
●s
or bonding
proceed
eVO~
as follows
.
(see
Attach grounding
cable with
144
To ground UC-12 aircraft
figure
2-107):
when
M83413-1 electrical
ground connector
static
t
llb5
..—
)
I
0
1
146
MIL-XDBK-274(M)
1 ?lovmb~r
1983
147
MIL-HDBK-274(AS)
1 November 1983
1=
MIL-HDBK-274(AS)
1 November 1983
b.
c,
d,
Q.
Connect fro? mid of ground!ng cable to nOOP vhcl axle (2),
If this
location
ic not scces~iblc.
th?n conn?ct troundin8
c~bl~ tom~in
wheel axle (typical
alternat~
groundin~ point),
If u.in~ fuel truck.
●ttach
its *rounding
csbl~ to ● ewtffhd
~round
or psd~y~ (3),
static
Conrwct fuel truck bondia~ cabl?
When fuelin~/defu~llns
wolution
to main whetlaxls
(4),
hac bwn compl~t?d~
●
wit
minimum
of 2 min before
f.
To tamow
removing bondin8 cable.
&rounding or bondinu csblos rw?rst abovt
2.1,126
lllslz~
durins maintc~ancecvol~tion
●,
b.
c,
Attach
70 ground
in the hangar,
grounding
csble
with
proceed
tU33413-1
●
t followo
cl~ctricsl
procedures,
UC-12 ●ircraft
(SeC figure 2-108)t
8round
courmctor
(clsmp type) to a certified
power &round (l).
Connect frw
●nd of grounding cable to nom vh~el ●xle (2).
If this
locstion
then connect
groundinu
cable
to maim
slt~rnate
grounding
point).
wheel ●xle (typicsl
To remove grounding
cable.
r?vt?rae above procedures.
.
2.1.127
~
~
To ground UC-12 ●ircraft
evolution
on the
with XEPP plugged into ●ircraft,
proceed aB follows
(Bee figure 2-109):
a.
Attach grounding
cable with
NOTE:
If
muet
b.
the MEPP is an electrically-driven
be used.
If
the MEPP is
bonding
d.
●.
K83413-1 electrical
8round connector
static
type,
then
a
power
ground
cable to nose wheel ●xle (2).
If this
location
io not ●cceaaible,
then connect groundinB
cable to main
wheel axle (typical
●lternate
grounding
point).
NOTE:
c,
apron
requirement
●
●ngine-driven
diesel
is
type,
then
the
following
waived.
bonding
cable with Ff83413-1 electrical
main wheel axle (3).
Connect free end of bonding cable to a bare
(4).
To remove grounding
or bonding cable,
reverse
Attach
ground
metal
connector
area
on
the
to
XJ?PP
abov~ procedures.
2.2
~~d
~
proceThe following
paragraphs
provide
step-by-step
dures for grounding
carrier-based
aircraft.
Note that the word “carrier”
is
meant to refer to any ship which supports
aircraft
flight
operation.
Before
●ttaching
grounding
cables.
●nsure
that the aircraft
has been tied down and secured
to the carrier
deck.
Tiedown chains cannot be relied
upon for grounding.
A
grounding
cable must be used to properly
implement the grounding
methodo presented
in this section.
Maintenance
type while
●volitions
the parked
and fueling evolution
are
and stores
loading/unloading
149
repres~nted
●volitions
for
● re
each aircraft
illustrated
for
0
W
b-
-1—
\
FIGURE 2-108.
CERTIFIEL)GROUNO
(LESS THAN 10OHMS)
w
\\i
\]
““x
.
●d UC-12 ~r~
?%(7
“,,-,.,A.,,C
TO EXTERNAL DC POWER
RECEPTACLE LOCATEO BENEATH
THE WiNG OUTBOARD OF
.
.
CAUTION
EARTH GROUND POINT
MUSTBE FREEOF
PAINTANOCORROSION
.
etQ&LMQL
x’
//?
, ,,,
w
HIL-HDBK-274(AS)
1 November 1983
151
BfIL-EDBX-274(A6)
1 ?Jwember1983
)
Aetack
A-7
2-116
apscial
Elocttonieo
Pishtm
Amti-6ubm4rino
&2
?-14
s-s
OR-2
2-127
2-134
2-141
2-144
a.licOpt.;
To 8rouud
2,2.1
A-3 ●irc?aft
●,
b.
c,
d.
●.
2.2.2
●ircraft
wlm~ fuelin~
or
defueling,
b.
follow
carriw-baccd
2-110);
(set figure
Crounding
cable with Ul!3413-1
electrical
~round conxwctor
(Clamp type) to ● padeye (1).
Connoct free cnd of grounding
cable to nose landing
gear (2).
If thio
locstion
iB not accessible,
cable to main sear
tiadovn
ring (typical
●lternate
grounding
point).
If using P!EPP. sttach
bonding cable with H83M3-1 ●lectrical
ground
connector
to
nom
landing gear (3).
Conntct fr~e end of bonding cable to ● bare metal ● r~a on the MEPP
(4).
To rmov~
grounding
or bonding cable,
reverse
sbov? procedurm.
Attaeb
a.
●s
proceed
Attach
proceed
To ground carrier-baaed
SS follows
(see figure
A-3
2-111):
ground connmtor
padeye (l).
end of grounding
cable
to nose landing
gear (2).
type)
Connect
free
is
to
not
●
accessible,
then
connect
grounding
grounding point).
cable
to
If
main
this
gear
d.
●lternate
If using MEPP, attach
bonding cable with lW?3413-1 electrical ground
connector
to nose landing
gear (3).
Connect free end of bonding cable to ● bare metal ● rea on the MEPP
e.
To remove grounding
c.
I
grounding
(clamp
location
evolution,
(4).
2,2.3
A-4 ●ircraft
●.
b.
c.
d.
wh& fueling
Attach
or bonding
or defueling,
grounding
cable
with
cable,
proceed
M83413-1
●s
rwerse
follows
electrical
●bove procedure-.
To ground carritr-bamd
(see figure
2-112):
ground
connector
(clamp type) to a padeye (1).
receptacle
(typical)
(2)0
If grounding
receptacles
are not accessible,
then uoing a Brounding
ground connector
step a~ ●nd connect free end of grounding
ring (typical
alternate
grounding
point).
bonding cable vith M83413-I ●lectrical
ground
connector
to nose gear tiedown ring (3).
152
I
MIL-HDBK-274(AS)
1 November 1983
ii
P
-.
xIL-ED8K-274(A2)
1 Novaber
1983
)
I
154
‘L
—
FIGURE 2-112.
CAUTION
TIE DOWN RING
MUST BE FREE OF
PAINT ANO CORROSION
(
-M83413 1
cONNECTOR
r
TYPICAL
ALTF RNATE GROUNDING i
POINT USING cONNECTOR \/
1>
~d
A-4 ~
I
WARNING
SEPARATE GROUNDING
CABLE MUST BE USED
.
.
‘T~
pA~~~i.ON
&
‘~”
.
nlll
10J
.
MIL-EDBK-274(As)
1 November 1983
●.
Connect free end of bonding c~ble to 8 bare metal ● rea on the UEPP
(4).
TO remove grounding
or bonding cable,
reverse
●bove procedure.
f.
2.2.4
aircraft
~A-4~
●.
b.
.
●volition,
ground carrier-based
as follows
(see figure
Attach
grounding
ground
(clamp type)
to a padeye (1).
Connect
●.
ring (typical
alternate
grounding
point).
bonding cable with m3413-1
If using XEPP, attach
connector
to nose gear ti~down ring (3).
Connect
free
end Of bonding
cable to ● bare metal
f.
(4).
To rmove
grounding
or bonding
csble.
reverse
2.2,5
●.
b.
c*
d.
F.
2.2.6
Iircraft
when fueling
or defu~ling,
arpa
above
•~
b.
c.
d.
●.
proceed
●s
foll~a
(see
on
ground
the MEPP
procedures.
carrier-baa?d
2-114):
figure
Attach grounding
ground conn~ctor
(clamp type) to a padeye (l).
ring
(2).
If
this location
cable to tail
bumper (typical
●lternate
grounding
point).
If using
MEPP, ●ttach bonding cable with ~3413-1
●lectrical
ground
connector
to noee gear tiedown ring (3).
Connect free ●nd of bonding cable to ● bare metal ● rea on the MZPP
(4).
TO r~ove
grounding
or bonding cable,
reverse
●bove procedures.
~pr-~.
●.
2.2,7
●lectrical
To ground
A-6 aircraft
conmctor
receptacle
(typical)
(2).
If grounding
receptacles
ar~ not ●ccessible,
cable with M83413-I ●lectrical
ground connector
● t ●ach ●nd,
follow
step ● . ●nd connect free end of grounding
cable
to nose gear tiedown
c.
d.
A-4
2-113):
To
proceed
evolution.
.
proceed
To ground
●t
follows
carrier-bated
(ace figure
I
A-6
2-115):
Attach grounding
cable with l@3413-1 electrical
ground connector
end of grounding
cable
to ●ain gear tiedovn
ring
(2).
If
Connect
free
cable to tail
thic
location
is not ●cc~ssibleo
bumper (typical
alternate
grounding
point).
If using =Pp,
attach
bonding
c~ble with M83413-I
electrical
ground
connector
Connect free end of bonding cable to ● bare metal area on the M!PP
(4) ,
To remove grounding
or bonding cable,
reverse
●bove procedures.
(A-7.
~
a~en
A-4.
A-6. ~-0.
To ground
EA-6)~
carrier-based
●ttack
I
156
MIL-HDBK-274(AB )
1 Novmber
1983
1
/
157
MUST
BE USED
WARNING
BE USEOTOGROUND AIRCRAFT,
E
L
OF
. . -/
mm
RING
------
ML-HDBK-274(AS)
1 November 1983
o
159
MIL-8DBK-274(AB)
1 November 1983
gircraft
~fticmd
when in tht
follow
●
c,
●volution
parked
●nd ctoreo
Attsch
8rounding
(CkUp
type)
ccble
to
●
M83413-1 ●l~ctrical
with
padcye
ground connector
(1),
c.
d,
To rmom
riat
(typical
●ltwaat~
groundint
cable,
r~~rse
grounding
point),
●bow procoduros.
2.2.8
aircraft
vht~
s.
b.
c.
d.
Q.
f.
2.2.9
aircraft
)
Connect free and of rounding cable to forward fumlase
grouudi~
roceptsclt
(typical f (2)0
If grounding receptacles
are not ●ccessible,
then umitt8 8 Srouadina
8round eottncctor ●t ●ch cads follow
@top a, ●td conaect
froc ●nd of Srouadiat cablo to nom t~m
tichvm
b,
A’7
●volutioth
lo&ding/unloadin8
(me fi~re 2-116):
fuelin~
or defucling,
proceed
To grouad csrrim-bas?d
(se~ figure
2-l17)t
Attach grounding
(clamp type)
to ● padeye (l).
cable
to forward
receptacle
(typical)
(2).
ground
connector
fuselage
8rounding
If grounding
receptacl~s
● rc mot sccecsible,
then usins ● #rounding
cable with X83413-1 ●lectrical
ground connector
● t ●ach
end.
follow
step ● , ●nd connect free ●nd of grounding
ring (typical
slternate
grounding
point).
bonding cable with M83413-1 ●lectrical
ground
connector
to nose gear tiedown rins (3).
end of bonding cable to ● bare metal ● rea on the XEPP
Connect free
(4).
To remove grounding
or bonding
cable,
reverse
●bov~ procedur~s.
.
~
●.
follows
●
.
evolution,
To ground
proceed
●s
follows
carrier-baaed
(Dee fi~re
A-7
2-118)x
●,
Attach grounding
cable with M83413-1 ?Iectrical
ground connector
cable to forward fuselage
8rounding
receptacle
(typical)
(2).
If grounding
receptacles
● re not accessible,
ground connector
● t ●ach ●nd,
follow
step ● . ●nd connectfree end of grounding
cable
to nose sear tiedown
●lternate
8rounding
point).
ring (typical
If using XEPP, ●ttach bonding cable with M83413-1 ●lectrical
ground
connector
to nooe gear tiedown rin8 (3).
Connect free ●nd of bonding cable to ● bare metal ● rm on the MEPP
f.
To rmove
b.
C.
d.
(4).
2.2.10
AH--l ●ircraft
●.
when
grounding
fueling
or bonding
or defueling,
cable,
proceed
rwersc
●s
follows
grounding
Attach
160
●bow
procedures.
To ground carrier-based
(see figure
2-l19)t
ground
connector
MIL-IIDBK-274(M )
1 Nov-ber
1983
161
MIL-HDBK-274(AS)
1 Novanbcr
1983
)
l-”
w
m
I
162
—
WL-?IDBR-274(M)
I November 1983
P
163
MIL-EDBK-274(AS)
1 Novmber
1983
I
164
?fIL-EDBK-274(AS )
1 Rwember
cable
Connect
Xf this
location
is not scceanible.
b,
when iu the mimtenenw
●
right
twins
ring
●olutfon.
proceed
●
(2).
csbl?
To gro&d
carrier-baaed
s follo-
(Me
fime
to
A21-1
2-120):
groundin~
csble
with X83413-1
electrical
ground connector
(1).
(Chmp ty~]
to ● padeye
Connect
free end of grouuding
cable
to front risht
towing ring (2).
then connect wounding cable to
If this
locttioa
ic not ●ccessible.
●ltern8te
groundin8
point).
front left
towing ring
(typic-l
To r~ov?
grounding
csble, reverse
●bove procedures.
.
Attsch
b.
c.
2.2.12
●ircraft
when fueling
AV-8
or defueling.
proceed
●s
&.
Attach grounding
csble
with M83413-1
(clamp type) to ● padeye (l).
b.
Counect
follows
To ground carri~r-based
(@e@figure
2-121):
●lectrical
ground
cormector
c.
cable to outrigger
gear tiedown ring
free ●nd of ~rounding
thim location
ia not ●ccessible}
then connect
grounding
to bottom part of outrigger
gear leg (typical
●lternate
Srounding
point).
bonding
cable with MB3413-1 ●lectrical
ground
If using XKPP, ●ttsch
d.
Connect
(2),
cable
If
connector
free
to main wheel ●xle (3).
end of bonding cable to
(4)0
20 remove grounding
or bonding
cable,
2.2.13
●ircraft
front
to
front l~ft towins ring (typical
●lternat~
grouading point).
To rcmov~ grounding
cableo
reverse●bovt procedures.
c.
2.2.11
●ircrsft
1983
●
bsrc
metal
●.
Attach
(clamp
C~ct
b.
maintenance
evolution,
proceed
●o
on
KEPP
the
●bove procedure~a
reverse
To ground
when in the
● rea
follow
carrier-baaed
(see
figure
AV-8
2-122):
grounding
csble with HB3413-1 electrical
ground connector
type) to ● padeye (l).
fr~e end of grounding
cable to outrigger
gear tiedown ring
locction
i. not accessible,
If this
to bottom part of outrigger
8ear leg (typical
●lternate
cabie
8rounding
point).
If using
d.
?!EPP, cttach
ground
connector
to main wheel ●xle (3).
Connect free end of bonding cable to a bar~ metal ● r~a on the HEPP
●.
(4).
To remove
c.
grounding
or bonding
cable reverseabove procedure.
c-1
2.2.14
C-1 ●ircraft
when fu~ling
or defuelin~,
proceed
●e
follows
To ground carri_r-ba@@d
(see fi~re
2-123):
ground connector
to a padcye (l).
cable to nooe gear towing ring (2).
b.
this location
cable to
main gear tiedown
ring (typical
slternate
grounding
point).
rmerse
above procedures.
c, To rmvv~ $rounding cable,
●
. Attach grounding
(clmp
Connect
type)
165
If
—.
MIL-EDBK-274(AS)
1 November
I
166
1983
&
1
MIL-EDBK-274(M)
1 November 1983
,P
w
167
FIGURE 2-122.
~
B
CABLE
All -“8 ~
-%=2!%
EXT ~R
SOURCE –
NC2AOR DECK EOGE P(WER /
WARNING
TIE OCMN CHAINS CAN NOT
MUST 8E USFO
.
/..,–
\
//
.
PAINT ANO CORROSION
——--- . ------
GROUNOIW CABLE CONNECTTO
TIE ~
RIWG
/77
mll
1,0
MIL-HDBK-274(M )
1 Novmber 1983
m
N
A
MIL-HDBK-274(As)
1 November 1983
2,2.15
aircraft
~ed
c-1
~
a.
b.
c.
b.
c.
do
●.
f.
2.2.17
~
CH-53 aircraft
2-126):
a.
To ground
proceed
as follows
carri~r-baaed
C-1
(see figure 2-124):
Attach grounding
ground connector
cable to nose gear towing ring (2).
this location
ia not ●ccessible,
cable
to
main gear tiedown
To remove grounding
2.2.16
~
based CH-53 aircraft
2-125):
a.
•~
evolution,
CR-53 ~
when fueling
ring (typical
alternatt
cable.
reverse
above
.
grounding
procedures.
.
or defueling,
proceed
point).
To $round carrieras follws (see figure
grounding
ground connector
(clamp type) to e padeye (l).
cable to left rear fuselage
grounding
receptacle
(2),
If grounding
receptacle
ia not acceaaible,
then ucing a grounding
cable with X83413-1 el~ctrical
ground connector
● t ●ach ●nd,
follow
cable to main gear ●tatic
drag wire (typical
alternate
grounding
point).
bonding cable with ?f83413-1 ●lectrical
ground
connector
to static
drag wire (3).
Connect free end of bonding cable to a bare metal area on the KEPP
(4).
TO r~ove
grounding
or bonding cable,
reverse
above procedures.
Attach
CH-57 ~rwhen in the maintenanc~
ev~
●volition,
To ground carri~r-baaed
proceed aa followc
(ree figure
Q.
Attach grounding
cable with H83413-1 electrical
ground connector
(clamp type)
to
a padeye
(l).
Connect free end of grounding cable to left rear fuoelage
grounding
receptacle
(2),
If grounding
receptacle
iB not ●ccessible,
ground connector
● t ●ach end,
follow
step a, ●nd connect free ●nd of grounding
cable to main gear static
drag wire (typical
alternate
grounding
point),
If using MEPp, attach bonding cable with M83413-1 ●lectrical
ground
connector
to static
drag wire (3).
Connect free ●nd of bonding cable to ● bare metal ● rpa on the MEPP
f.
To remove grounding
b.
c.
d.
(4).
2.2.18
or bonding
.
~?
cable,
reverse
above
procedures.
.
(E-2) ~
special
●lectronics
(E-2) ●ircraft
when in the parked evolution
and in the storro
loading/unloading
●volition,
proceed as follows
(see figure
2-127):
a.
Attach
(clamp
grounding
type)
cable with ~3413-1
to a padeye (l).
170
electrical
ground
connector
If
WARNING
SEPARATE GROUNDING cABLE
MUST BE USED
/
\
~
RING MUST
LIEFREE OF
●AWIT ANO ~RR~~
~,E
UM413 1
-
E)(1 mER
s@JRCE -
“ U*A
o
I
NC 2A OR DECK EDGE PWER
1%-L )
m
PADEYE
~
BE FREE OF
PAINT AND CORROsl~
1
YO
(Xmcw
d
—
.—c
MIL-EDBK-274(AB)
1 November 1983
)
/
l=+=%k!u!!?
Wqy’‘
172
—
w
-1
w
‘Ec’:;wy
m
FIGURE 2-126
●
~;
L
‘
o
“
Ff?
(_/--(#l4’4
1
ho
–
PADEYE
MUST BE FREE Of
PAINT AND CORRtXlffl
\
$-z
H
CAUTION
\
PAOFYf MUST BE FREE OF
PAINT AND CORRosloN
\
\
\
“A
FIGURE
2-127.
~
of pAINT AND CORROsION
TIE DOWN RING MUST BE FREE
~CABLE
/’
dQ!J/
\lB@/
.
.
.
K/
(E-2) ~
evo ~
ALTERNATE
GRWNDING POINT
. .. --— . .------USINGCUNNt CI~
NOSE GEAR
LOOKING FORWARD
Y
WARNING
BE USED TO GROUND AIRCRAFT,
MUST BE USED
MIL-EDBK-274(AS )
1 November 1983
b.
c.
Connect free end of
If this location
is
drag brace on nose
TO remove grounding
grounding
cable to main gear tiedowm ring (2).
not accessible,
cable to
gear (typical
alternate
grounding
point).
cable.
reverse
above pro-dur-.
2.2.19
~+d
E-2 ~
E-2 aircraft
when fueling
or defueling.
a.
b.
c.
d.
e.
2,2.20
aircraft
c.
d.
e.
2.2.21
~
EA-6 aircraft
a.
b.
proceed
as follows
To ground carrier-baaed
(se@ figure
2-128):
grounding
ground connector
cable to main gear tiedown ring (2).
If this location
is not accessible,
cable to
drag brace on nose gear (typical
alternate
grounding
point).
If using MEPP. attach
bonding cable with M83413-1 ●lectrical
ground
connector
to main gear tiedown
ring
(3).
Connect free end of bonding cable to a bare metal area on the XEPP
(4)*
To r~ove
grounding
or bonding cables
reverse
above procedures.
~*
b.
.
Attach
-ulh&ML
a.
.
evolutions
proceed
To ground carrier-baeed
as follows
(ace figure
E-2
2-129):
Attach grounding
ground connector
cable to main gear tiedown ring (2).
If this location
is not accessible.
cable to
drag brace on nose gear (typical
alternate
grounding
point).
ground
connector
to main gear tiedown ring (3).
Connect free end of bonding cable to a bare metal area
on the MEPP
(4).
To rcsnove grounding
or bonding cable.
reverse
above procedures.
M-6
when fueling
or defueling,
proceed
as follws
(see firre
2-~30):
Attach grounding
cable with !483413-1 electrical
ground connector
cable
If this location
is not accessible,
cable to
bracket
inside
nose wheel well (typical
alternate
grounding
point).
c.
If using
KEPP, attach
connector
to bracket
electrical
d.
Connect
area
e.
To remove grounding
free
bonding
cable with M83413-1
inside
nose wheel well (3).
end of bonding cable to a bare metal
on the
ground
MEPP
(4).
2.2.22 ~
EA-6
aircraft
a.
or bonding
evolution,
cable,
proceed
Attach grounding
cable with l@3413-1
175
reverse
above
To ground
as follows
electrical
procedures.
carrier-based
(see figure
ground
EA-6
2-131):
conn~ctor
-%P\/
FIGURE 2-128.
cAuTlm
TIE ~
RING MuST BE FREE
PRESSURE
FUfllNG
ADAPTF R CAP
\
~
/
CAUA
\
a.
*
NC 7A OR DECK EffiF ~ER
Ii== ll\
E-2 ~
PADEYE M(JSTBE FREE OF
PAIN I AND CORROSION
//
/7
/)
wARwwm
.
;i
TIE I)(JWi CMA!NSCAN ~
BE USED TO GR(X)ND AIRCRAFT.
SEPARATE GROUNOtNG CA9LE
MJST FIEuSED
n
.
FOHWARO
‘-R
LOOKlffi
FIGURE 2-129.
~-2
~
.
WARNING
BE USED TO GROUND AIRCftAFT,
MUST 8E USED
.
?IUL-EIM-274(AS)
1 Nowmber
178
1983
FIGURE2-131.
EXTEI?NAL POWER
RECEPTACLE
4
EXT POWi~
NC 2AOR DECK
VIEW LOOUING AFT
/
.—-.
—.
.
HIL-HDBK-274(AS)
1 Nov-ber
1983
b.
co
d.
e.
Connect free end of
If this location
it
inside
nose
bracket
connector
to bracket
Connect free end of
(4).
To remove grounding
grounding
cablt
to main gear tiedoun ring (2).
not ●ccessible,
then connect
grounding
cable
to
wheel wel] (typical
alt~rnate
grounding
point).
bonding cable vith l@3413-1 electrical
ground
inside
nose wheel well (3).
bonding cable to a bar~ met~l area ou the MEPP
or bonding
cable.
.
@VO~ .
proceed ae foll~s
2.2.23
~cl
F-4 ~
F-4 aircraft
when fueling
or defueling,
●bove procedur~s.
reverse
(see figure 2-132):
a.
Attach
b.
nacelle
grounding
receptacle
(typical)
(2).
If grounding
receptacles
are not accessible,
then using a 6rounding
ground connector
at ●ach end, follow
cable vith
otep a, and connect
cable
to main gear tiedown
c.
Brounding cable with M83413-1 electrical
Connect free end of grounding cable to engine
ground
ring (typical
alternate
grounding
point).
bonding cable with X83413-1
connector
to main gear
tiedown ring (3).
Connect free end of bonding cable to a bare metal
d.
e.
connector
●lectrical
area
on
ground
the MEPP
(4).
To remove
f.
2.2.24
aircraft
grounding
.
~e
when
a.
b.
in the maintenance
d.
e.
f.
2.2.25
evolution,
~ed
(typical)
f~
aircraft
proceed
a.
P~
evolution,
cable,
.
proceed
rweree
above procedures.
To ground
ae follows
carrier-based
(~ee figure
ground
nacelle
F-4
2-133):
connector
grounding
(2).
If grounding
receptacles
are not accessible,
ground connector
● t each end,
follow
cable to main 8ear tiedown
ring (typical
alternate
grounding
point).
bonding cable vith M83413-1 electrical
ground
connector
(4).
To remove grounding
or bonding cable,
reverse
above procedures.
r~a
F-14, F-18)
bonding
Attach grounding
cable with X83413-1 ●lectrical
cable to ●ngine
receptacl~
c.
or
(F-4.F-14.F-18] ~
when in the parked evolution
and stores
as follows
(see figure
2-134):
Attach grounding
cable with M83413-1
180
electrical
fighter
(F-49
loading/unloading
ground
connector
)
MIL-RDBX-274(M)
1 Nowmber 1983
I
i!!
u
b
181
.—.
—
MIL-HDBK-274(AS)
1 November 1983
182
MIL-HDBK-274(AS)
1 November 1983
———
—
141L-EDBK-274(As)
1 November 1983
b.
●nd of grounding csblt to lover torque
● rm pin
on nose
is not ●cccscibleo
then connect
If this location
grounding
esble
to nose gear ti~down rin$ (typical
●lternat~
grounding point).
To r~ovc
~toundhs
cable~ mvarse ●bove proc~duraa.
Connect
free
gaar (2).
c,
2,2.26
?-14 ●ircraft whe; fueling
8.
Attach groundin$
(clamp
b,
c.
d.
●.
or chfuelin$,
type)
to
proceed
padoye
groundins point).
cable with H83413-1 ●l~ctrical
ground
If usint MEPP, ●ttach bonding
conmctor
to lower torque
● m pin
(3)0
Connect free
end of bonding cable to bare met~l
● rea on the MEPP
(4).
To rmove
grounding
or bonding
cable,
rwerae
●bove procedures.
evolution,
b.
Connect free end of
If thio
gear (2).
grounding cable to
grounding
point).
connector
to lwer
Connect free end of
(4).
To remove grounding
e.
2.2.28
F-18 sircraft
when fueling
●.
b.
c.
ground connector
cabl~ to lower torque 8= pin on nose
If this locstion
i- not accecaible.
then connect
~aar (2).
slternste
$roundinc
cable
to nooe gear tiedown ring (typical
Attsch
grounding
cable with M83413-1
(clamp type)
to ● padeye (l).
d.
To ground currim-b~~ed
(Dae figure 2-lS5)t
(1)*
a.
c.
fellow
cable with M83413-1 ●l?ctrieal
●
2,2,27
3-14 ●ircraft
2-136):
as
To ground c~rrier-bas~d
proceed ● s follows
(see figure
electrical
ground
connector
grounding
cable to lwer
torque ●rm pin on nose
location
is not •cc~-sible,
then connect
nose gear tiedovn ring (typical
●lternate
torque am pin (3)0
bonding cable to bare metal ● r?a on the
or bonding
or defueling,
cable.
proceed
●s
reverse
follows
ground
MEPP
above procedures.
To ground carrier-bas~d
(see figure
2-137)$
grounding
ground connector
cable to note wheel well grounding
receptacle
(typical)
(2).
If grounding
receptacle
● re not acceceible,
then ucin6 ● sroundins
ground
connector
● t ●ach
ends follow
otep a. and connect free end of grounding
ring (typical
alternate
groundin8 point).
Attach
184
)
~
4
BONDING
CABLE
FIGURE 2-135.
EXT POWFFlSOURCE NC 2A OR OECK EDGE POWER
-.
/
CORD
~d
F-14
PAINT At$i%’:ROSION
CAUTION
PADEYE MUST BE
GROUNDING
CABLE
~
~
WARNING
BE USED TO GROUNOAIRCRAf T.
SEPARATE GROUNOING CAELE
MUST BE USED
\
.
b
3-
LOWER TOROUE
ARM PIN
m3413 1
(X)NNECTOR
J
\
2
I
I
o
o
I
1
I
\uq
}
\
.
A~TEWATE
,
GROUNDING POINT
USING CONNECTOR
\
Pfi
ml t??
ON
PTACLE
.—
.-—
————
XIL-?UM-274(M)
1 Novmber 1983
)
186
MIL-HDBK-274(AS)
1 Novmber 1983
g
.
i
lv\LLL
1,
I
/3Mid
r
\
Mii
‘\
It
@
1’
$ VF+%--l
187
‘KLki)
““W
MIL-EDBK-274(As)
1 November 1983
using MEPP, attach bonding
cable with X83413-1 ●lectrical ground
connector to main gear tiedown ring (3).
● . Connect free ●nd of
bonding cable to ● bar~ metal ● rea on the UEPP
2.2.29
d.
If
f.
(4).
To remove grounding or
~nv~e
F-18 aircraft when in the maintemnce
2-138):
bonding cable, reverse ●bove procedures.
.
To ground carrier-baard
evolution, proceed ● s follows (see figure
a.
b. Connect free end of grounding cable to nose wheel well grounding
c. If grounding receptacles ar~ not accessible. then using a grounding
cable with N83413-1 electrical ground connector
● t ●ach end, follow
step ● . ●nd connect free ●nd of grounding cable to main gear tiedovn
ring (typical ●lternate.grounding point).
d. If using KEPP, attach
boding
cable with M83413-1 ●lectrical ground
connector to main gear tiedowriring (3).
● . Connect free end of bonding cable to ● bare metal ● rea on the MEPP
(4).
f.
To rmuove grounding or bonding cable. rwerse
●bove procedures.
2.2.30 ~
H-46
E-46 aircraft when fueling
or defueling, proceed as follows (see fiwre 2-139):
b. Connect free end of grounding cable to left main gear tow fitting
point (2). If this location ia not ●ccessible. then connect
grounding cable to right main gear
tow fitting point (typical
●lternate grounding point).
c* If using MEPP, ●ttach bonding cable with M83413-1 electrical ground
connector to left main gear tow fitting point (3).
d. Connect free ●nd of bonding cable to a bare metal area on the MEPP
a.
●.
(4).
To r~ove
grounding or bonding cable, rwerse
●bove procedures.
.
2.2.31 ~d
E-46 ~
To ground carrier-baa~d
H-46 ●ircraft when in the maintenance evolution. proceed ● s followc (see figure
2-140):
b. Connect free end of grounding cable to left main gear tow fitting
point (2). If this location is not ●ccessible, then connect
grounding cable to right main gear tow fitting point (typical
alternate grounding point).
c, If using MEPP, attach bonding cable with B183413-1●lectrical ground
connector to left main gear tow fitting point (3).
d. Connect free ●nd of bonding cable to ● bare metal ●r?a on the UEPP
a.
●.
(4).
To rmovt
Srounding or bonding cables rwerse
188
●bove procedure~o
XIL-HDBK-274(AS)
1 Novrmber 1983
189
_.. —
P!IL-HDBK-274(AS)
1 November 1983
190
—
NIL-MDBK-274(AS)
1 November 1983
.
191
MIL-EDBX-274(M)
1 November 1983
2.2.32
~-
vlmn in the parked ●volution ●nd storet loadin#/unloadin8 ?volution. proceed sc
follow- (me
●.
b.
C,
d.
2.2.33
3-3 ●ircraft
2-141):
figur~
Attsch Srounding
csble with MB3413-1 slcctrical ground cons.ctor
(C18EP type) to a Pcdsys (1).
Corm.ct free and of troundins cable to pyloe groue&lns roc.ptael.
(typical) (2).
If Srounding
roccptacloc
● ro not ●ccoasiblat
th-usims
● v-d~w
cable with MM413=1 ●lcctrical $round conm~etor ●t .acb ecidtfollow
otep ● o ●nd conn~ct free .md of groundins csblc to aoo~ sear tidown
ring (typical ●lternete grounding point).
To rmow
grounding cable. reverse ●bove procaduros.
when
fueling or d~fueling, proceed
To groumd carrier-based
follows (mt figure
2-142):
d.
●.
connector
to no-e gear tiedown
ring (3).
Connect
free end of bonding ceble to ● hart
f.
(4).
To runov~ grounding or bonding csble, rwers~ ●bovQ procedur~s.
b.
c.
Attsch
2.2.34 ~d
aircraft
●s
grounding
cable with MB3413-I ●lectrical $rouad coawctor
(cl-p type) to ● pedeye (l).
Connect free end of groundinc cable to pylon grounding
receptacle
(typical) (2)0
If groundin~
receptacles •r~ not scccscibl?. them U@iBB ● sr=md~~$
cable with M83413-1 electrical ground connector ●t ●ach ●nd. follow
st~p •~ ●nd connect free end of grounding cable to nose gear tiedown
ring (typical alternstc grounding point).
If ucing MEPP, attach
bonding
cable with M83413-1 ●lectric~l
ground
●.
when
m~
S-7~*
in
the meinteuencc evolution.
proceed
t
m?tsl
● r~a
on the HEPP
To Sround carri?r-ba~cd
S-3
follows
(see figur~ 2-143):
●S
Attach grounding cable with X83413-1 electrical ground connector
(clemp type) to ● padeye (l).
b.
Connect
free
end of grounding
cabl~ to pylon grounding receptacle
(typical) (2).
receptacl~~
● re not ●ccessible, then u8in8 ● tr~ndiw
c. If $rounding
cable with ● M13413-1 electrical ground connector
● t ●ach d.
step a, ●nd connect free ●ud of groundin
c~ble
to nose sear
follow
tiedown ring (typical ●lternate grounding poiat! .
d. If using MEPP, ●ttach bonding cable with MS3413-1 electrical Srouad
to nose gem tiedom ring (3).
connector
●,
Connect
free
end of bonding
cable to ● hart mctsl ● rea on the XEP?
●.
f.
)
(4).
‘To remove
grounding or bonding csble. reverse ●bove procedures.
2.2.35
To ground carrim-bastd
192
,
HIL-HDBK-274(AS)
1 ??owmber 1983
a’
193
/@!z@k
SINGLE pOINT
/
-----
TO “
HOSE
HOSE
\-FuELING
II
i-ntdNci-7
Tn
GROlJNOlNGCA6LE’~
Z
MUST13E USED
%%ioN”tt’pA
)11-111
‘o’
T’”
WARNING
BE USEO TO GROUND AIRCRAFT.
SEPARATE GROUNOING CAB1. E
FIGURE 2-143.
I
~
GRO
1
s-3
~
.
“ 1~:,’j
CAUTM
PADEYE
MUST BE FRFEOF
PAINT ANO CORROSION
‘-$
wc—=————
1-
CAUTION
TIE ~
RING MUST
9E FREE OF
PAINT AND CORROSION
WARWNG
TIE ~
CHAWS CAN W)T
BE USED TO GRWND AIRCRAFT.
MUST BE USED
.
~
W31
IIq
—
XIL-EDBK-274(AS)
] l’lovmber
1983
helicopter aircraft
(AH-l, CE-53, ~-~,
~-a, SR-30 SR-60) fieu
in
the perked
●volution ●nd store. loading/unloading ●volition. proceed ● s follows (see figur~
2-144):
●.
b.
c.
d.
Attach
grounding cable with M3413-1 electrical
ground connector
(l).
(clamp type)
to ● pedeye
Connect
free ead of ~rounding cable to front left fuselage grounding
receptacle (2).
If grounding receptacle is not ●ccessible, then using ● grounding
csble with M3413-1 ●lectrical ground connector ● t ●ach ●nd, follow
step ● . ●nd connect
free end of grounding cable to main gear tiedown
ring (typical ~lt~rnate
grounding
point).
To remove 8rounding cable, reverse ●bove procedures.
2.2.36
W-2
aircraft when fueling or d~fueling, proceed
●.
b.
)
●s
To ground carrim-based
Connect free end of grounding cable to front left fuselsge grounding
receptacle
(2).
If grounding receptacle ia not ●ccessible. then using ● grounding
cable with ● MS3413-1 electrical ground connector ● t ●ach ●ndo
follow step a, ●nd connect free ●nd of grounding cable to main gear
d. If using MEPP, ●ttach bonding cable with HS3413-1 electrical ground
● . Connect free end of bonding
cable
to s bar~ metal ● rea on the MEPP
C.
f.
(4).
To rmnov~
grounding
or bonding
cable, reverse
2.2.37
SE-2 ●ircraft when in the mintemnce
2-146):
a.
be
evolution,
●bove procedur~a.
To ground carrier-bamed
proceed as follows (see figure
Attach grounding csble with l@3413-1 electrical ground connector
Connect free end of grounding cable to front left fuselage grounding
receptacle
(2).
e.
If grouading receptacle is not ●ccessible. then using ● grounding
cable with ● M3413-1 electrical ground connector ● t ●ach ends
follow step ● , ●nd connect free ●nd of grounding cable to main gear
tiedown ring (typical alternate
grounding
point).
If wing ~PPO
●ttsch boding
cable with X83413-1 electrical ground
f.
(4) .
C.
d.
.1
196
MIL-EDBK-274(AS)
1 November 1983
a
i
197
——
MIL-EDBK-274(AB)
1 ?Jov-ber 1983
c
*IY
‘“
t!!s
‘“
o~
198
?!IL-EDBK-274(M)
1 November 1983
L./l /
\
199
MIL-EDBK-274(A8)
1 November 1983
2.2.38
SR-3 ●ircraft vhen fueling or defueling, proceed
●s
To ground carrier-bas~d
follova (see figure 2-147):
Attach grounding cable with M83U3-1 ●lectrical ground connpctor
drag wire bolt
b. Connect free end of grounding cable to the static
If this location
then connect
6YOUZdi8g
(2).
cable
to main gear tiedovn ring (typical ●lternat~ grounding
point).
c. If using MEPP, attach bonding cable with M83413-1 electrical ground
connector to main gear ticdown ring (3).
d.
Connect
free
●nd of bonding cable to ● bare metal ● rea on the MEPP
8.
●.
2.2.39
SE-3 ●ircraft
2-148):
(4).
To remove grounding or bonding cable, reverse ●bove procedures.
when
.
●v~
in the maintenance ●volition, proceed ● a follows (see figure
SE-3 ~-
Attach grounding cable with M83413-1 ●lectrical ground conn~ctor
b. Connect free end of grounding cable to the static drag wire bolt
(2). If this location is not accessible, then connect grounding
cable to main gear tiedovn ring (typical alternate grounding
point).
c. If using MEPP, attach bonding cable vith ?4’83413-1
●lectrical ground
d. Connect free ●nd of bonding cable to a bare metal area on the MEPP
(4).
t. To remove grounding or bonding cable, reverse above procedure.
s.
.
.
.
2.2.40 ~-60
~
To ground
carrier-based SH-60 aircraft vhen fueling or defueling. proceed ● s follows (ace
figure 2-149):
. Attach grounding cable with M83413-I ●lectrical ground conn~ctor
b. Connect free end of grounding cable to fuselage grounding receptacle
(typical) (2).
C.
If grounding receptacl~s
ar~ not ●cceaaible,
cable with X83413-1 ●lectrical ground connector ● t ●ach end, follow
step a, and connect free end of grounding cable to etatic drag vire
(typical alternate grounding point).
d. If using MEPP, attach bonding cable with MS3413-1 ●lectrical ground
connector to static drag vire (3).
● . Connect free end of bonding cable to ● bare metal
● rea on the MEPP
(4).
f.
To rmove grounding or bonding cable, reverse ●bove procedures.
●
2.2,41 ~
●vc&@J&
To ground carrier-bas?d
SH-60 ●ircraft when in the maintenance evolution. proceed ● s follows (see figure
2-150):
a.
Attach
grounding cable with ?483413-1electrical ground connector
200
)
MIL-EDBK-276(AS )
1 November 1983
201
\
RECEEVACLF
/
\
b.
FIGURE 2-148. ~
=7
MOOEL SN 3N HELl~f6
OEIAIL A
\
1
w
0I
-“
1. 0 lt--f~)?–
m
“–
/
3
/’0.
●
v- .5.%?%?7/
F
CAUTION
TIE DOWN RING
MLKT OE FREE OF
PAINT ANO CORROSION
TYPICAL
ALTERNATE GROUNOING
MODEL SH 30 HELICOPTERS
‘“”: [
/
EXT POWER SOURCE
NC 2A OR DECK EDGE -R
0/
m
/’
CAUTION
PAOEYE MUST BE
FREE OF
PAINT ANO CORROSION
WIRE BOLT
WARNING
TIE D(MN CHAINS CAN NOT
MUST 8E USED
!?2
SU*
w
XIL-BDBK-274(AS)
1 Rovmber
203
1983
—..
.—
.—.
HIL-HDBK-274(AB)
1 November 1983
MIL-EDBX-274(AB)
1 November 1983
b.
Connect frw
end of grounding cable to fuoelage grounding
rmeptacle
(typical) (2).
c. If grounding receptacles ● re not accessible. then using ● grounding
cable with M83413-1 electrical ground connector ●t each ends follow
step ● . ●nd connect
fret end of grounding cable to static
drag wire
alternate grounding point).
(typical
electrical
~rommd
d. If using MEPP, attach bonding cable with Uf.13413-l
connector to static drag wire (3).
e.
Connect free end of bonding cable to a bare metal ● rea on the MZPP
(4).
TO remove grounding or bonding cable. reverse ●bove procedures
f.
.
2,3
~
The follwing paragraphs provide tcp-by-step
c~dures for static grounding hovering helicopters.
2.3.J
load transfer, proceed
a.
b.
c.
2.3.2
~
●s
follow
pro-
To static ground hovering helicopter during
(eee figure
2-151);
Ueing the helicopter
static
charge grounding wand. ●ttach ?@3413-1
connector (clamp) to a certified static ground or padeye (l). If
permanent grounds are not availabl~ during shore-based operations,
drive the grounding
wand”e associated ground stake 18 inches into
the earth and attach connector.
Make contact with the helicopter frame or hoist cable using the
grounding wand hook (2). This contact mutt be continuous until
hoi~t cable is ready to be retracted into helicopter.
When hoist cable is ready to be retracted. release grounding wand in
reverse order of hookup.
.,
To ground
hovering
helicopter
during refueling ●volition, proceed as follows (see figure 2-152):
a.
b.
C.
Using the helicopter static charge grounding wand, attach the M83413-1
connector
(clamp) to a certifi~d static ground or padeye (1).
Make contact with the helicopter hoist cable using the grounding wand
hook (2). Thio contact must be continuous until hoist cable ●nd fuel
hose are connected.
Once hoist cable and fuel hose are connected, release
grounding
wand
in reverse order of hookup.
2.3.3
hovering helicopters (SH-60B)
figure 2-153):
a.
●.
T)
To ground
employing the R4ST eyatem, proceed as follms (ace
Using the helicopter static charge grounding wand, attach the M83413-1
connector (clamp) to a padeye (1).
205
MIL-EDBK-274(As)
1 November 1983
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MIL-EDBK-274(M)
1 November 1983
/I
4
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WL-DBK-274(AS)
1 knwmber
1983
.
208
4
MIL-EDBK-274(AS)
1 November 1963
b.
c.
Make contact with the messenger cable using the grounding wsnd hook
(2). This contact must be continuous until messenger cable probe is
secured to the RAST cable (3).
@ricemessenger
cable and MST cable are connected. releao~ grounding
wand in reverse
order of hookup.
2.4
The following paragraph provide step-by-step
grounding ●nd bonding procedures for a generic type ●ircraft using various
carrier-based ●nd chore-baned external electrical power sources. 8hipboard deck
edge power~ FLEDSt and various MEPPS are illustrated, Grounding and bonding
procedures for ●ircraft fueling/defueling operations requiring external ●lectrical
power are also included with the A-6 chosen as an example. These procedur~a ● re
further diacuaaed ●nd amplifid in paragraph 3.3. These bonding and grounding
procedures must be performed prior to connection of external power cables.
z.4.1
~
deck edge power, proceed
a.
b.
c.
●s
To static ground aircraft when using
follows (tee figure 2-154):
Connect free end of grounding cable to an approved grounding point on
the aircraft (2).
To rartovegrounding cable, reverse above procedures.
2,4.2 ~
figure 2-155):
To ground aircraft when powered by FLEDS, proceed as follcws (see
Attach grounding cable with HS3413-1 ●lectrical ground connector
b. Connect free end of grounding cable to an approved grounding point on
the aircraft (2).
c. Attach cable with M83413-1 connector
to an approved grounding or
bonding point on the aircraft (3).
d. Connect free ●nd of cable to a bare metal area on the DBA, such as the
st~ or bolt (4).
● . To r~ove
cables,
reverse
above procedures.
a.
2.4.3 W-1ATo ground aircraft when using the UUG-lA MEPP. proceed ● n
a.
b. Connect free end of grounding cable to an approved grounding point on
the aircraft (2).
c. Attach bonding cable with M83413-1 connector to an approved grounding
or bonding point on the aircraft (3).
d. Connect free end of bonding cable to a bare m~tal area on the HEPP
(4)*
● . To remove cablea, reverse above procedures.
209
.-
0
?IaIRB
2-154.
~
●
?AOEVE MJST DE
FREE OF
●AINT ANO (X)RROSION
‘oI
-131
CtNNECTOR
GRoLJNotNG
CABLE
z
0
—
.
.
FLIOMT
DECH
EXmRNAL
$031
16?
1
o
CAUTION
ALL ATTACHMENT POINTS
MUST BE FREE OF
PAINT AND CORROSION
CERTIFIED STATIC
GROUNO
IL ESSTHAN 10,OWOHMS~
M83413 1
CONNECTOR
GROUNDING
CABLE
h
FIGURE 2-155. ~
.
CONNECTOR
4
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OaA
.
-xu
MIL-HDBK-274(AS)
I Novemb~r 1983
9
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212
XIL-EDEX-274(AS )
1 I!ovember 1983
2.4.4 xc~MxzL
To round ●ircrsft
follows (OO; figure 2-157! t
●.
Attach groundiu8 cable
b,
(clm$
tyue)
Connect
f~.a
tho sircrsft
MOTBt W
u~e
●lectrical
with ?lB341S-1
to ● padoye (1).
●nd of”trounding
cable to
●n
ground
proc*ed
●s
connector
●pprowd
Smundhg
toquired
for airersft
point
on
(2).
followin8 bondiat
28 vdc
when using the ltC-2AWPPD
pwm
procodura
is not
that
only.
d.
Attach boadiaa csble with MID413-1 connector
to ● n ●pprwod
sroundhg
point
on th~ ●ircraft
(3).
or bonding
Connect
free ●ad of bondin8 cable to a bsxe metal ●rm on the MEPP
c.
To rmove
c.
(4)0
2.4.5
~
follows (see figure
●.
b.
cables.
To round
2-158 ! :
rweroe
●ircraft
●bove
procedures.
when u#ing the
NC-8A MEPP. proceed aa
Attach $roundins
cable with X63413-1 ●lectrical ground connector
(clamp type) to ● certified
static ground or padeyc (1).
Connect free end of groundins cable to ●n ●pproved grouudin~ point
the ●ircraft
(2).
on
I?OTE: The following bonding procedure i. not required for ●ircraft that
use 28 vdc power only.
d.
bonding csble with M83413-1 connector to ●n ●pproved grounding
or bonding point on the ●ircraft (3),
●.
To remove cable.. reverse
c.
Attach
(4)*
●bove procedure-.
2.4.6 ~
To 8round ●ircraft when uoing the NC-1OC UEPP. proceed as
follows (see figure 2-159)t
s.
b.
Attach
grounding cable with M83413-1 ●lectrical ground connector
(clamp type)
to ● c~rtified static ground or padeyc (1).
Connect free end of grounding cable to ● n approved grounding point on
the ●ircraft (2).
NOTE:
c.
The folkwia~ bonding procedure
use 28 vdc power only.
F.
not
required for ●ircraft that
bonding cable with M83413-1 connector to ●n cpproved -rounding
bondin8 point on the aircraft
(3).
Connect free ●nd of bonding csble to ● bare metal ● rea on the !4EP?
(4)*
To r~ove cabless reverse ●bove procedures.
Attach
or
d.
is
213
FIGURE
CAUTION
PADEYE MUST
BE FREE OF
PAINT ANO CORROSION
e
\loy1
/1
2-157. ~
*I
1
.
‘\
K
.
POWER
EXTERNAL
BONDING
CABL [
,
.
M83413 I
CONNECTOR
4
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MIL-EDBK-274(AS)
1 November 1983
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215
IfIL-HDBK-274(As)
1 November 1983
)
u
A
MIL-HDBK-274(A8)
1 November 1983
2.5
paragraphs
.
.
~
de8cribe
the
procedures
required
[A-L
The f 01 lowing
to ground A-6 ●ircraft in the fueling
●volution using ext~rnal ●lectrical power.
b.
grounding cable with M83413-I electrical ground connector
(clamp type) to a certified static ground (l).
c.
location
is not accessible,
then connect
grounding
cable
to the main
If using fuel truck. attach its grounding cable to a certified static
a.
Attach
d. Connect fuel truck bonding cable to nose gem tiedown ring (4).
● . Attach fuel nozzle ground connector to nose gear tiedown ring (5).
f. Attach external power source bonding cable with M83413-1 electrical
ground connector to main gear tiedown rin8 (6).
Connect free end of bonding cable to ● bare metal area on the ●xternal
%*
electrical power source (7).
h.
When fueling/defueling ●volution has been completed, wait a minimum of
above procedures.
i. To remove grounding or bonding cables reverse
NOTE: Aircraft must be grounded to
10 ohms.
a.
b.
c.
d.
e.
f.
h.
i.
●
certified power ground
of
less than
Attach grounding cable with M’83413-1●lectrical ground connector
location is not accessible. then connect grounding cable to the main
gear tiedovn rin8 (typical alternate grounding point).
If using fuel truck, attach ita grounding cable to a power ground (3).
Connect fuel truck bonding cable to nose gear tiedown rin8 (4).
Attach fuel nozzle ground connector to nose gear tiedown ring (5).
Attach external power source bonding cable with M83413-1 electrical
ground connector to main gear tiedown ring (6).
Connect free end of bonding cable to a bare metal ar~a on the ●xt~mal
electrical power source (7).
When fueling/defueling ~volution haa been compl~ted, wait a mininntmof
2 min before r~oving bonding cable.
To rmnove grounding or bonding cable, reverse ●bove procedures.
217
.—
MIL-EDBK-274(As)
1 November 1983
u
218
—
HIL-HDBK-274(AS)
1 November 1983
a
o
—.
HIL-HDBK-274(AS )
1 Novmber 1983
2.5.3 ~
by Z
when using external power, proceed
●
To ground ●ircraft in the fueling
●volution
(clamp type) to a certified static ground (1).
b. Connect free end of grounding cable to aircraft grounding point
(2). If this location is not accessible, then connect grounding cable
to the main gear tiedown ring (typical alternate grounding point).
c. If using fuel truck, attach its grounding cable to ● c~rtified static
Connect fuel truck bonding cabl~ to nooe gear tiedovn ring (4).
d.
A.
●.
Attach
fuel
nozzle
ground
connector
to
nose
gear
tiedown
ring
(5).
Attach ●xternal power source bonding cable with MB3413-1 electrical
ground connector to ●ircraft grounding point (6).
Connect free end of bonding cable to a bare metal ● rea on the ●xternal
●lectrical power source (DBA) (7).
h. When fueling/defueling ●volution has been completed, wait ● minimum of
2 niin before
removing bonding cable.
i. To remow grounding or bonding cabl~, reverse above procedures.
f.
2.5,4 ~Pd
bv dw~
under deck edge power refer to paragraph 2.2.
For grounding ●ircraft
2.6
Since aircraft engines are operating during hot fueling
operations additional external pwer
in not required. The fueling ●volitions
described in paragraph 2.1 are applicable to hot fueling from trucke. Shipboard
hot fueling procedures are similar to those described in paragraph 2.2, ●xcept
external power sources are not connected.
2.6.1
Fueling from hydrant~ requires static grounding. If
ground points ● re not available at the hydrant #tations, then static grounding muot
be ●ccomplished by bonding the airfr~e to the hydrsnt ground cable. Grounding ●nd
lxmding procedures ●nd sequences are identical to the fueling ●volitions depicted
in paragraph 2.1.
2.6.2 ~
Fueling from bladders requiree static grounding of
..iircraft.For hot refueling from a bladder, the ●ircraft muet be bonded to the
external fuel pump ground stake. Grounding ●nd bonding procedures ●nd mequ~nces
%re identical to the fueling evolutions depicted in paragraph 2.1.
220
)
MIL-HDBK-274(A8)
1 Novtmber 1983
c
Al
221
MIL-HDBK-274(AS)
1 November 1983
SECTION3
)
This section provides personnel with the neceBaary information to understand the
_,ezdfor grounding and bonding.
This section discuuws the grounding problems and
hazards encountered in everyday ground handling of aircraft during flight
operations. Descriptions are given of static electricity, energy sources, and
grounding effecte. Various aircraft ecewrioe are preacnted that involve safety~elated servicing situation, together vith the approved methods of handling 6uch
problems.
. .
3.1 we
@16+~
This is defined as tfelectricity at rests” ●nd
coaaists of electrical charges (positive and negative) that are usually kept ●part
flow and accumulation are small (in the range of only
by incubators.
Although
thousandths of an ampere). voltages may rise to many thousands. A well-known
example of static electricity is the diecharge ($parking) of an accumulat~d charge
built up on a person who has walked on a carpet in a dry room, and touche6 a metal
door handle or radiator.
3.1.1 Materials are compos~d of atoms, which include electrons and protons. An
electron is a particle of negative charge, and a proton ia a particle of positive
charge.
Normally,
in any given
material,
the electrons
and protons are balanced,
so that there is no net electrical charge. However. if the material is subjected
to some fo~ of friction, come of the electrons will break away from their atoms,
leaving the material
with a positive charge due to an excess of protons. In other
situations, a substance or person may be left with an exceeieof electrons~ and have
a negative charge. Either of these unbalanced conditions gives rise to the existence of a static electrical charge in the material or person involved.
I
3.1.2 The process
by vhich a neutral
at~
bec~es
positively or negatively
charged through rmoval or addition of electrons is called ionization. WhCJn
ionization is completed. the charged atom (called an ion) has an electrostatic
field surrounding it. This electrostatic field is comparable to the magnetic field
that exists ●round a magnetic pole. A large accumulation of positive or negative
~.;~acreates a strong electrostatic field, an effect that may be Been in a dry room
Yhen a comb is passed quickly through a person’s hair. The comb accumulates
cactain charges, leaving the hair depleted of thoee charges. The e+l~ctroatatic
?ield created around the strands of hair causes the hair to ‘~stand on ●nd.vt
3.1.3 The accumulation of Static electricity creates potentials ranging from a
few volts to thouaando of volts. If two charged hodies are brought
to
within
a
dietance
shorter
than needed for breakdown of the air betwe?n them, a discharge
will result, similar to what occurs in lightning. In the case of lightning. the
clouds become highly charged to the point that there is enough voltage buildup to
cause a discharge, either from cloud to ground, or from one cloud to another,
whichever
is
closer.
3.1.4 In the earlier cases of the person walking on the carpet, and the c~b
pnaaing through hair, emphasis
had been placed on a dry atmofiphere. had room
humidity been high, the accumulation of water particles would have provided ● path
f.>.:
the negative charges to travel to the positively charged material. and thus
..,;:vantedbuildup of excessive electrostatic voltages.
222
I
UIL-HDBK-274(AS)
1 November 1983
3.1.5
comes
0P5,
●lectricity
and how it
●xcerpt
from NAVSEA
The following
Now that there is some understanding of static
about,
Volume
how seriously
1
should
it
be taken?
summarizes thic matter:
9? ...Failure co take all known precaution to avoid the accumulation of
chargee of static electricity or to safely
dissipate such charges may
result
in disaster, The generation of static electricity caanot be
prevented ●ntirely. Its generation ig not in itself a hazard provided
it can be dissipated safely. The hazard is ●ncountered when charges
accumulate to the extent that ● spark discharge occurs to oome other
object in the presence of hazardous atmospheres~ dusts- or ●xposed
sensitive ~xplomives. Elimination of such potmtial hazards, therefore. requires proper grounding
or neutralization of the charges to
avoid dangeroua ●ccumulation.”
3.2 ~
Evaluation of ● situation’s potential hazards is baeed on
the source mechanism and the source magnitude of the electrical energy. With
operations involving aircraft such as stereo handling, maintcnancet fuelings ●nd
aircraft parking, the follwing energy sources must be considered:
a.
b.
Static
● Triboelectric
● Induced
● Friction
Power
● Ground Fault
● RF Electromagnetic Energy
● Lightning
The static eourceB Ii#ted above are defined and
3.2.1 ~
evaluated in the following paragraphs.
3.2.1.1 ~C
P~
These ● re generally associated with buildup of
can result
static charge~ on ●n aircraft in flight. High static voltages, however,
from interaction at the contact eurfacee of various materials in ●ny type of relative motion. eg, wind-blown cnowb or dust particleo otriking a parked aircraft. A
conservative estimate of electrical current in a moderate wind-blown dust situation
ia 30 microampere.
This type of static electricity ie aleo called precipitation
static or p-static. Connecting the aircraft frame to ●n approv~d static ground
point providee a conductive path back to ground for the etatic charges ae they ar?
generated. A static ground point is defined as a ground point having less than
10.000 ohms impedance to ●arth.
3.2.1 .1.1 A helicopter exemplifies triboelectric effects.
to 1000V are normally generated by a hovering helicopter.
conditions charges up to l~OOO~OOOV have been recorded.
Static
voltages
of UP
In exceptional weather
3.2.1 .1.2 Personnel must ust extreme care when ●pproaching a hovering ●ircrsft.
Strict observance of the prescribed sircraft manual procedure will prevent the
eerioug injury certain to occur if the aircraft ia touched prior to grounding.
223
MIL-EDBK-274(AS)
1 November 1983
3’2”1*2 ~
Paragraph
3.1.2
described
th~ basic
mmwr
in
which static ●lectricity
●nd ●lectrostatic
fields ● ? Bmcratcd. An ●mmplc $ivon
cwsht
tho hsir to ~totmd
on
was that of paasint ~ comb through onQ~s hair,
nc~ativcly
•id.~~ On s much larter scale, durirq storm activity~ cloudo becmt
shuted ●nd create a powerful
●lectrostatic fhld,
As ● bi$hly eharsed Clwd
pa$s?s over a parked ●ircraft, the ●lcctrootatic
field emces th~ ●ircreft to
charged.
become punitively
me posftive chuses ● re cosductad frcm the ~rouud~ UP
through the tires,
buildint Up chuses of up to 600000V on tho ●ircrcft,
Thee@ ● c
eallad induced chuses~
If tht storm cloud 10SQS its nesative
ch8rs@D ?ithm
M s
discharse to snother cloud or to some spot on the ground. or emn if the
li$htni~
force of the acgative
chugc holdint
storm cloud merely WVQO OU, the el~ctrostatic
the pooitive char~e on the ●ircraft disappears. The positive chu$~ on the
●ircraft
will now r~turu to ground via the tires, Should the tir~ resiataace be
hi8hs the discharge time may be long. Should ● person touch the ●ircraft ●nd
provide ●n alternate path to ground, the person will receive s shock which normally
may do no more ham than to C8USCS 10SE of balance, with perhaps ● fall to the
grouad. However, on rar~ occasions the shock could be serious. If the person has
been in contact with the aircraft throughout the charging period, ie, as the
charged cloud movem 610vly overhead, the person will probably f~el no effect, If
the cloud ●bove suddenly discharges to another cloud. the charged aircraft
inzaediat~lydi~chargeE back to ground via whatever path is available, which
includes the person touching the aircraft, The person will now probably feel a
sharp chock, the oeverity
of which depends on the extent to which the ●ircraft was
originally charged. It can be spen that if the ●ircraft were connected to ● otatic
ground point (less than 10,000 ohms), the positive charg~ would take thim path of
least resistance back to ground
and
thus
provide protection to personn@l working
●bout the ●ircraft.
3.2.1.3
~
Static
●lectricity
is generated
when certain materials rub
together. During such close moving contact between two materials, on- of the
materials is depleted of ●lectrons, causing a surplus in the second. The magnitude
of the static electrical charge thus produced depend. on the materials involved ●nd
on the amount of humidity present during such friction. With synthetic materials
(such as nylon) underdoing friction
in ● cold dry climat~. the effect is greater.
Voltages ● a high ● s 270000v have in some instances been recorded. Because of
hazarda presented by such high charges,
perconnel subject~d to such conditions must
bring themselves
to the same voltage potential
● c the
●ircraft
●nd weapon system.
static
●lectricity
is increased
in dry ●tmosphere.
$ince the risk of generating
Juch ritk is decreased
in a damp. hishly humid ●tmosphere which inhibits the
accumulation of static ●lectrical charges. Moisture in the ●ir or on the skin
provides ● conductive path for the pocitive
●nd negative Chargec to be rejoined,
neutralizing the static charges. To further protect againat the ●ffectt of
friction, it is essential that the aircraft be grounded.
3.2.1
.3.1
static
●lectrical
charges
are gen?rated on clothing by friction.
raaoving garments. Since clothing is largely
of
mynthetic material, which ~plifie~ the ●ffects of friction. personnel ohould
exercise extreme caution in areao where hazardous conditions may be present. The
removal of clothing therefore,
should be prohibited, especially in dry climates.
during fueling and ordnance operation, The buildup of static electrical chargee
can be minimized by uee of cotton clothing
and ●ntistatic powders,
●specially by the action
of
I
224
F!IL-HDBK-274(AS )
1 November 1983
3.2.1.3.2 The friction generated in fueling ● ●ircraft. with pa-ssge of fuel
from the supply vehicle through the fueling host to the sircraft, generates high
electrical charges. Charge separation ●nd consequent buildup
of electrostatic
charges occur between the moviug fuel ●nd fuel filters hosc~ ●nd other surfaces.
fuel is normally ● excellent insulator. separated chsrges ● r? ●asily rmoved
Since
by the flowing fuel to a dictant location. If no ●lectrically conductive r~turn
path is ●vailable. the charge accumulateon metallic surfaceo, ●nd i. ● high
With the continued
●ccumulation
of charge.
sufficient
potential
energy
source.
el~ctrical potmtial is generated to cause ●n arc scross
insulating barri-rs.
These volta~en build up within the ●ircraft fuel tank ●nd ● re ● serious danger.
Were these voltages to arc over to points of lower potential with the right fuelBonding tbe aircraft
frame to
air vapor mixture preaento ●n explosion would occur.
the fuel supply vehicl~ provides a means of dissipating these high voltages,
Bonding do?s not prevent generation
of high voltages
within
hose or tanko but
provides a return path for the accumulated
charges
● s contact
is made with the
tank surface.
inside
fuel
3.2.1.4 ~
Various cources of static ●lectricity, such ● s triboelectric,
●ffects
of
induced charge, ●nd friction have been discussed. In general, direct
static electricity are not serious, ●lthough such shocks can cause involuntary
reflex movements resulting in injury to the ●ffected person or others nearby. On
the other hands sparks generated in the vicinity
of ● fueling
operation
can have
recults. Catastrophic results can occur from discharge of static
dimaotrouu
electricity into ● squibb cartricige~or electroexplosive device (EED). Carp in
eneuring that ●ircraft- weapon systems fueling system, ●nd personnel ● rc kept ● t
ground potential will minimize the dangerous ●ffectc
of static ●lectricity, A
ground of up to 10~000 ohms io considered ● n ●d~quate safety
me-sure.
3.2.2 ~
Various types of electrical power, ●uch ● s 115V ● c, 28V dc,
lightning, ●nd radio frequency (rf) ●re discussed in the following paragraphs. The
term power used in this cont~xt ● ssumes ●lectric
current
flow measurable
in amPcD
in contrast to static ●lectricity whose current flows typically. is in the rans~ of
thousandth of ●n mmpere.
3.2.2,1
During ●ircraft flight, s11 ●lectric
power required
by onboard ●quipment is supplied by generators driven by the sircraft
ensines.
NO
basic types of electrical voltage are used; 28 volts. direct current (de) ●nd 115
volts alternating current (ac)O ● t 400 Eertz.
The 28V dc system is ● two-wire system, positive ●nd negative, with the negative
side of the system connected to the
●ircraft structure. The 115v ● e ia ● four-wire system conaiatin8 of phaaee A. B,
C, and neutral (1?).with the neutral wire connected to the ●ircraft structure.
Equipment using ac power may uce either single phase power consisting of neutral
●nd phase A? Bg or C. or 3-phase power which requires phaoes AO Bo C. ●nd N.
3.2.2.1.1 When the ●ircraft
is on the ground, it is not practical to run the
engines for ●lectrical power, so the required ● c ●nd dc power is supplied by
generator external to the aircraft. These sources may be mobile or fixed. The
❑obile sources arc called Mobile Electric
Power Plants (MEPP). Following ● rc ● few
examples.
225
MIL-EDBK-274(AS)
1 November 1983
Ship
NC-2A
Engine-driven,
Flight Line
NC-8A
Engine-driven, self-propelled
s~lf-propelled
115/200V
● C, 400 Ez
30 WA, 28V de. 500A
)
115/200V ● C, 400 k.
28V dc, 500A
60 WA,
Flight Line
NC-1OC
Engine-driven, e~lf-propelled
115/200V ● C, 400 h,
90 kVA, 28V dc, 750A
Hangar
MUG-1A
El?ctric motor-driven
trailer-mounted
115/200V ● C, 400 HZ,
60 kVA, 28V dc, 500A
A complete listing of KEPPO, together with a description of ●ach model, ia given in
BAVAIR publication 19-45-1.
3.2.2,1.2 Figure 3-1 shows a typical ●xample of an aircraft supplied with ●xt~rnal power in a shore base flight line configuration. Thc ● e and de genwators ● re
diesel engine-driven and ● re mounted on a self-propell?d chassis on rubber tires.
The ac neutral (N) and dc negative wires are both connected
to the cha$sie.
In
this configuration, the supply cablee provided with the HEPP ● re about 30 ft long,
The ac and dc connector plugs are standard MS fittings which mate with moat ●ircraft. Alt~rnative equipment used to provide extcmal ●lectric power in:
a.
b.
c.
MMG-1. This is an ●lectric motor-driven MEPP, normally umd inside hangara. The electric motor input ia 220/440V ● c, 3 phase,
60 Hz. The input power includes a safety ground line which ia
connected to the KEPP chaasis. The generator output neutral is
also connected to the MEPPchaoaia. Both ●ngine-driven ●nd motordriven MEPPS are bonded to the aircraft.
independent of the power
cable neutral or negative. Neither MEPP i, indepmdently
grounded.
Flight Line Electrical Distribution System (FLEDS). This system
ia installed on shore station aprona. Figure 3-2 shows ● typical
FLED layout. AC power ia provided to the system by a MEPP located at ● central location. The ● c neutral
line is connected
to
ground ● t the point of entry
to
the
FLEDS ●nd ●t the remote ●nda.
Distribution boxes (DBA) ●r~ provided ● t intemala
throughout the
●ach containing circuit breakerso overload relays. and
system,
service cables to supply two ●ircraft.
The distribution cabl~a
are protcct~d from taxiing ●ircraft
by metal ramp.
Deck Edge Power. This ia ● similar system to the FLEDS ●xcept for
being installed aboard an ●ircraft carrier. The 115V ac. 400-Rz
generator is driven by an ●lectric motor fed from the 220/440
Vat, 3-phaae, 60-Hz, three-wir~ d~lta system. Aboard ship, the
3-phaoe, 60-Iizsystem is not grounded.
3.2.2 .1.3 The 115V ac, 3-phase, 400-Hz power is fed to the aircraft via a
standard connector. This connector (MS 25486) has six connections, A, P, C, ●nd N
~-:,r
the 3-phase ac; and E and F for control purposes only. The manner in which E
.>ndF are connected varie6 from aircraft to aircraft. The 28V dc supply is fed to
226
I
MIL-MDBK-274(AS)
1 Novmtb@r 1983
CONNECTOR
MS 25486
i
AIRCRAFT
STRUC~URE
POWER
OLT,
60 Hz
J
cONNECTOR
MS 25487/8
CERTIFIED
PowER GROUND
(LEss THAN 100HMSI
ELECTRIC
%+;;NG
MOTOR ORIVEN
CONNECTOR
MS 2S466
I
AIRCRAFT
>1
‘-RuCTURE
EXTERNAL
GROUND
CABLE
MS27574
r
I
I
-C-RUBBER
TIRES—
.
J
CONNECTOR
MS 254878
CE RTIFIED STATIC
GROUND
(LESS THAN IO,OGQOHMSJ
OIEsEL
ENGINE
‘BoNDING
CABLE
DRIVEN
,C,,
FIGURE 3-10
227
.;
g-
CERTIFIED
GROUND
FIGURE 3-2. ~
(LESS THAN 10.OCNJ
OHMS)
(
*
—
=
●
MEPP
.
/
.
=
GROUND
.
fLESS THAN 10.000 OHMS)
CERTIFIED
GROUNDING
BONDING
n
T
503143
f3 PLACES)
PROTEcTION
GNO
FLEOS
LIGHTNING
EXISTING
MIL-EDBK-274(AS )
1 November 1983
the ●ircraft
by ● separate
3-pin
connector.
The connector ia designed in ●ccordMS 25487 or U8 25488. Ia ●ach case, two pine ● re for 28V dc positive ●nd
me~ative, with the third pin for ●ircraft
control
purpoaec.
●ce
with
3.2.2.1.4 Prior to mating the power connectors to the ●ircraft. be cure that the
sircrsft is connected to ● power Sround (se~ paragraph 3.3). The purpose of thic
ic to provide protection s~ainst ground power fault for all personnel working on or
●bout the ●ircraft,
● fault
may occur in the ●l~ctrical
supply
sysOccasionally,
● t the
oupply connector, that results in the neutral line becoming
tems probably
disconnected from the ●ircraft ●nd a phame line contactin~ the ●ircraft
structure.
In this condition, the ●ircraft
skin is ssid to become ?~hot,~~
ie, with ●bout llSV
sc potential with respect to ground, If the ●ircraft im not connected to ground, ●
person standing on th~ ground who touches
the ●ircraft
could receive
a lethsl
chock, It is ●ccepted that ●lectrical voltages in ●xceco of 45V dc or 30V ● c C8U
give lethal shocks to humane. This it based on ● body resistance of 1!500ohms ●nd
lethal current lwels of 20mA ● c ●nd 30mA dc .
3.2.2.1.5 8ince the predominant fault mode concerns the ●xternal power SUPPIY
connector, one cannot rely on the neutral connection to the ●ircraft
to provide ●
fault return circuit to activate the overload trip. For that reacon~ it it nec●ssary to bond the ●ircraft to the ●xternal ●lectrical power source. ie~ the ~pp
or FLED distribution box (DBA).
In the case of deck ●dge power~ thim has already
been done vben the aircraft ia grounded to the shipts
deck,
Uoually*
the power
required to ●ctivate the overlosd circuit is very high, well in excees of 100
amps. It it possible that the total resistance in the bond circuit will be high
●nough to restrict the current flow and thus prevent ●ctivation of the overload
circuit. In this case,
the bond strap betwem
●ircraft
and the MEPP might become
hot and cause the wire to overheat. A ‘famoking~t ground or bond wire im often the
firet indication of ●n ●lectrical circuit
problem,
●nd requires
that ●xternal
●lectrical power be #hut off immediately. .
3.2.2.1.6 In the case of the engine-driven I!EPp,the ●ircraft is grounded to an
approved static ground. Thim ground also serves to ground the XEPP via the ●xternal bond wire and, under normal circ~gtgncea, the sc neutral wire. It im then not
necessary to independently ground the engine-driven MEPP.
3.2.2.1.7 The motor-driven MEPP provides
a different
problem.
The XEPP motor is
● c.
60-Hz main system.
A 60-Hz supply
cable
includes
a
connected
to the 220/440V
ground wire connected directly to the HEPP chastia. When ● n ●ircraft ie
safety
connected to ● motor-driven MEPP. it is not uncommon for 115V ac. 60-Hz powered
equipment to be uc~d on or ●bout the aircraft. It then becomes ●csentisl that
should a fault occur in ●ny of the 60-Ez powered ●quipment. including the MEPP
motor.
that the aircraft be grounded to a low resistance point of lees than 10 ohms
in value which shall be connect~d to th? 60-?k power source ground system.
3.2.2.1.8
For aircraft being serwic~d inside a hangar this presents no problmn.
as all ●ircrsft ● re routinely connected to low rewiatauce points connecttd to the
60-Ez power ground. For aircraft parked on an apron end fed by a motor-driven generator? it may be difficult to locate a power ground of less than 10 ohmo. but
every effort should be mnde to meet thi8
requirement. It should be noted that 10
ohms io not a low enough
impedance to provide adequate short circuit protection at
all times against power ground faultao when the airframe may be at a 115V ac potential
The 10-ohm value was chosen as a practical
obtainable value to provide some
●
229
MIL-KDBK-274(AS)
1 November 1983
degree of safety and, at the same time. ●n adequate airframe eyetem ground. A
10-ohm ground resistance will not provide enough fault current to trip a 50-amp
circuit breakers nor will it cause a grounding cable to burn; in factc there may be
mO indication of ● fault. ‘l’he
wire may get too warm to touch if ● ground fault
exist8.
3.2.2.1.9 Since many ●lectrical problems are caused by defective cable plugs, it
ia imperative that cable plugs be carefully ●nd frequently ●xamined for bar~ or
broken wires or other dmage prior to connection to the ●ircraft. It is also
extrmnely important that the cable and connector be thoroughly checked and tested
after
repsir ●nd before being returned to service. The U.S. Wvy Support
Equipment, Basic Handling and SafetY ~nual, NAVAIR 00-80T-96. paragraph 3-320,
addresaeo the hazarda of electric
shock associated
with defective ●lectrical cablea
?ad connectors.
3.2.2.1.10 ne deck edge power supplied by the ~hip?a supply ia not grounded to
the ship’c structure. The neutral of the 3-phaae power is not tied to the ship~a
structure and therefore the syat~ represents a floating neutral power 6ourC~.
Deck edge configuration depicted in this handbook ●ctually indicate aircraft
static bonding to the deck.
3.2.2.2
Paragraph 3.1.3 provides ● simple ●xplanation of the
lightning phenomena. When a charge of sufficient magnitude builds up in a cloud,
preliminary breakdown occuro and a stepped leader ia initiated. As the stepped
leader neara the ●arth, upward~ving
diachurges may be produced from local high
points that are at or Dear ground potential. For this reaeon, the tail of an
●xposed aircraft often provides the primary ●ttacbent point for a stepped leader
(see figure 3-3). As the leader Complctee its path to ●arth, a return stroke is
generated. The current8 in return 8troke8 typically reach levels of 20.000
amperes, with peaka of up to 200 kiloamperes (KA) recorded. During the life of an
aircraft, it may be struck many times by lightning, but only on rare occaaions ia
damage sustained. Little can be done to prevent a lightning atrike to an aircraft
parked on a concrete/aephalt apron outaide a hangar. A 10V impedance ground will
reduce the amount of time required to bleed-off induced charge due to “nearby”
+
+
+
503144
++?
FIGURE 3-3.
~
230
)
ML-EDBK-274(AS)
1 November 1983
Iightaing, and reduce the chance of sideflashes. Of course, no ground will totally
protect personnel working on the exterior
of an aircraft
in the vicinity
of ●n
are
electrical
storm,
If weather
conditions
are such that lightning strikes
inaninent,
all
be suspended.
operations
involving
refueling~
ordnance
Ioadinga
or maintenance
must
Todayts environment has many unintended side
3.2.2.3
effect~ caused by radio frequency
(rf)
transmitting devices used in conjunction
●nd
with naval flight operations. Of concern ● re those high pwer comaamication
radar transmitters which may be located near parked aircraft. The best example of
situation is the carrier
flight deck, which probably containa the highest
this
of transmitted rf energy to be found on ●ny base from which aircraft
concentration
operate. Although high power communication
and radar tranmuittera
may be found at
diatancee from parked aircraft at a ohore #tation, an aircraft may be
greater
affected by an adjacent aircraft whose onboard communication systua or radar
transmitters are being tested. Aircraft aboard ship could be similarly affected.
3.2.2.3.1 The principal problem is the amount of rf energy induced into the
aircraft frame ●nd circulating on the aircraft skin. This quantity or level of rf
energy ia greatly affected by the position
of the aircraft relative to a particular
rf transmitters the power output of that transmitter- ●nd the actual frequency of
the rf energy being transmitted. It ia further ●ffected by the actual location of
any connections between aircraft and ground (deck). Where position of one ground
may have a significant ●ffect on induced current. other ground connections from
different locations on the aircraft to other locations on the deck may not have the
same effect. Any existing aircraft grounding scheme should not be altered in an
effort to provide the aircraft with additional protection against rf energy. If
the ground connection is broken while the rf transmission is in progreseg an
electric arc nay be drawn out. This is an important fact to note. If sn arc is
produced while disconnecting a ground, the source may be rf energy.
cauoed by a
local transmitter and the current flow can be high. (A power line short circuit CO
ground may also produce an arc when the ground is disconnected.) If. on the ocher
hand, an arc is drawn while a ground is being ●ttached to the aircraft, the sourcp
is static electricity and the current flow will be light.
3.2.2.3.2 Since there is no protection from transmitted rf energy, it is
necessary that personnel ●nsure that no operations are conducted without observation of all recommended procedures. For instance,
a fuel hose nozzle should
always be bonded to the aircraft before the filling cap ia removed and the hose
nozzle inserted into the fuel tank. Conversely. the filling cap should be replaced
before the hose nozzle bond ie disconnected from the aircraft. These procedures
will ensure that no rf arcs are inadvertently produced in a hazardous atmosphere
while the fuel tank cap is removed.
3.3
The following paragraphs summarize grounding and
bonding procedure performed during maintenance. fueling/refueling, and ordnance
handling evolutions. Note: Any area that the U83413-1 electrical ground connector
(clamp type) is clamped to should be free of paint. corrosion. dirt. grease and not
made of a compouite material. The clamp should be twisted to ensure that a good
electrical path is established.
3.3.1 ~e
the following items
~
must
When performing maintenance evolutions,
be considered.
231
!IfIL-EDBK-274(A8)
1 November 1983
3.3.1.1 Parked
10,000
●ircraft
must
b? grounded
to
●n
cpproved
static
groumd
(leDs
than
ohms).
3.3.1.2 Uhen performing
hangsr maint~nsnce, th~ ●ircraft
●pproved power ground (less thsn 10
must
be 8rounded to
●n
ohms).
3.3.1,3 When perfo~ing maintenance requiring
●xternal
●lectric
power.
the
8round must
An ●pprov~d static
aircraft must be grounded to ●n ●ppropriate ground,
be used if the external
source is ●n ●ngine-driven gemrator or PLEDS. A power
ground must be used whrn the extrrnal
source
is ● motor-dziven (60-Iiz)gewrator
●ven if 28V dc only
is connected
to the ●ircraft,
In ●ddition
to th~ required
static or power grounding, ●ircraft
must be bonded directly to the power source ● s
follows!
●
.
b.
to the ?4EPP chassis
(engine-driven or motor-driven).
Bonded to the DBA, if YLEDS io the powsr sourct.
Bonded
NOTE:
Exceptions
to the •bo~c ● r~: (1) when the aircraft
is power?d
from deck-edge
power on s ship.
grounding
to the deck only is
(2) where the ●ircraft will be fed from hangar bulkh~ad
required;
outlets, grounding only to power ground is r~quired; ●nd (3)~
●ircraft uuing 28V dc diesel gtnerat?d power only.
3.3.1.4
If the ●xternal power sourc~ is ●n ●ngin~-driven KEPP, the MEPPshall
not be independently grounded. Consequently, ● motor-driven generator is
indep~ndently grounded through ita own potter
supply cable, in ●ccordance
with the
National Electric Code with no ●dditional ground required,
3.3.2
.
~
The following paragraphs provide
grounding ●nd bonding procedures to be follw~d while performing various
fueling/refueling scenarios.
3.3.2,1 The grounding procedures to be obc~ned
with no ●xternal power required is ● s follows:
●
.
b.
C.
d.
e.
when
refueling
a perked sircraft
Ground aircraft by connecting ground cable (type MS27574) from any
●pproved static grounding point to ● grounding receptacle
on the
●ircraft.
static
ground point (use same point
Ground refueler
to ●n ●pproved
● s used by aircraft).
Bond refueler to aircraft using:
●
1st choice - approved grounding r~ceptacle
●
2nd choice - grounding
connector
(Type MIL-C-83413).
to be
attached
to a clean, unpainted metallic eurface.
Attach fuel delivery nozzle bonding cable to aircraft before
removing filler cap.
On completion of refueling operation, secure in reverse order to
above. Ensure filler cap io replaced before removing nozzle
bonding cable.
I
232
MIL-EDBK-274(AS)
1 November 1983
3.3 .2.2
The grounding
procedure
to be observed
when refueling
a parked
●ircraft
with external power required ig as follow#:
●✎
b.
Ground ●ircraft by connecting ground cable (type KS27574) from ●y
●pproved static
grounding
point to ● grounding recept~cle orIthe
●ircraft. When powered by ● diesel-dri~en generstor,
connect ●ircraft
to ● static ground. When powered by an electrically-drives
generator (W-1A). connect aircraft
to ● power ground.
Bond ●ircraft to ground power unit (CPU) using ● suitable grounding
cablt (Type MS 27574). The cable will be attached to the aircraft
by:
●
An ●pproved grounding receptacle, if available.
●
If not ●vailable, attach
to ● clean,
unpaint~d
mwallic
surface
● grounding
connector
(Type HIL-C-83413).
using
The other end of the grounding cable will be connected to the
c.
d.
e.
f.
g.
Mobile
Electric Power Plant (MEPP) by attaching the grounding connector
(Type MIL-C-83413) to ● clean. unpainted metallic surface.
Attach ●lectrical power cable(s) from MEPP to aircraft. Carefully
examine the 115V ● c ●rid/or28V dc connectors for any evidence of
damage prior to connecting to the aircraft
r~ceptacles.
Ground refueler by attaching grounding cable from refueler to ● n
approved otatic ground point. It io necessary to uce the same
ground as used by aircraft.
Bond refueler to aircraft using:
●
An approv~d grounding receptacle.
●
If grounding receptacle is not ●vsilable, attach to a clean~
unpainted metallic surface using a grounding connector (Type
MIL-C-83413).
Attach fuel delivery nozzle bonding cable to aircraft before
ranoving filler cap.
On completion of refueling operation. ●ecure in reverse
order to
nozzle
●bove, Ensure filler cap is replaced before r-oving
bonding cable. Remove ●ircraft/truck
bond.
NOTE:
The above procedure will apply regardless of whether the MEPP is
engine or ●n ●lectric motor. It is not
driven
by a diesel
necesoary to separately ground the MEPP.
The ●bov+ procedure will apply when aircraft is powered by PLEDS
or ship?. deck edge power. In the caae of REDS. the aircraft
will be bonded to the distribution box ●ssembly (DBA). On board
the carricrt the aircraft
need only be grounded to the deck.
It
noted that tiedown chaina do not provide
should be further
satisfactory grounding patha.
3.3.2.3 When the fueling operation ia being conducted on an icy, sandy, or rocky
terrain or where it may be impossible to adequately ground the aircraft~ precaution
must be taken to eneure that the bonding connections are solid and reliable.
During carrier operations, grounding to the carrier deck may be frustrat~d by the
use of padeyea which have been coated with nonekid epoxy.
The NAVAIR Airfranw
Grounding Report (AIR-5181-1000) cites the cane of an F-14 aircraftc
Electrical
oecured by 12 tiedown chains, which had a combined resistance to ground (deck) of
40,000 ohme. One chain alone measured 5 megohms from end to end. These conditions
233
MIL-HDBR-274(AS)
1 November 1983
emphasize the need for ●xtreme careo especially when the systm safety must rely
solely on good bonding. Aircraft
tires
may be exp~cted
to provide
some resistance
to ground;
however,
field
meaeurementa
have
indicated
●
wide
variation
in
)
In ●ddition, the @urface
from
2s000
ohm- to a high ma 600~000 megohms.
on which the aircraft is standing adds considerable resistance to that offered
by
the tires. The carrier deck nonskid surface ●nd black ●sphalt both offer very high
to routinely
inspect th
oerrier
resistance to ground. It ia a Dorsal procedure
deck padeyes and clean them of paint or nonskid material. Similarly the
‘tapprovedtf grounding points at ohore facilities are routinely inopected ●nd the
ground remittance ia meaaured and recorded.
resistances
3.3.2.4 It ia mandatory during a fueling operation
that
● n ●ircraft frame
be
connected to ground using a good ground cables with each ●nd of the cable nmted
using clean well-maintained connectors, Grounding the ●ircraft, howwer, will not
stop the genmation of electrostatic charges~ but will help bleed the charget away
before they build up high ●nough potential. to damage ●quipment or injure
increase the
personnel,
Additives
have been devised which. when ●dded to the fuel,
conductivity of the fuel. This means that the generat~d electrostatic chargea find
an eaaier path to ground and thus are prevented from building up to such high
valueo.
The uae of these additives is presently under study.
The follwing paragraphs provide
3.3.3
grounding consideration and procedures during ordnance handling operation.
3.3.3.1 During the loading or unloading of ordnance, the aircraft must be
appropriately grounded. Generally, external power is removed from the aircraft
during these operations, in which case+grounding to an approved static ground is
adequate.
3.3.3.2 Various aircraft loading and unloading manuals have cited the ●dequacy
of aircraft tiedown chains in providing suitable grounding. Unfortunately.
experience has shown that this ie not so and~ whereas a new chain will have a
ze+sistanceof less than 0.5 ohmo a ueed chain has been measured at 50000,000 ohms.
This ie due to excessive
corrosion, and this condition ia not improved when the
in6talled chain
is
being subjected to continuous movement when the ship is rolling
and the weight
of the aircraft ig continuously transferring from one chain to
~~~other.
3.3.3.3 In accordance with NAVSEA OP4, Volume 2, Fifth ReviaionD ‘sThe termination of a static ground path at any of the following points is sp~cifically
p~cihibited.
a.
Electrical conduits or wire coverings
b, Cam or steam pipee or tubing
c. Sprinkler systems
d. Air terminals for lightning protection
Power line neutral points
e.
f.
Hydraulic, fuel. or lubricating lines
Electronic transmitter cables, wave guideE, or ground leads
Signal ay~tem conduits.?!
:.
●
234
I
MIL-mB%-274(AS)
1 November 1983
Additionally. ●ll peroonntl involved in handling
ordnance should ground
3.3.3.4
themselves inaaedistelyprior to touching ●ny electrical connector, wire, or plug
Personnel
should ground themaelvea
by making momentary hart
connected
to a weapon.
skin-to-metal contact with ● grounded object or the metallic skin of the weapon.
In some locations, due to ●n extremely dry climate, local rules require that
personnel handling ordnance shall wear grounding straps or stirrups
which extend
from under the ●hoe to the upper calf.
Due to the obvious hazards in handling ordasnce, ●ll personnel should be
of the unique cbaracteriaticg of individual weapons by reviewing the
technical manual or OF for that weapon,
Familiarization with the contents of
Volume 2, Fifth Revision,
especially
paragraphs
2-36 through 2-450 is
MVSUOP4,
3.3.3.5
●ware
.advioed,
The following
●xcerpt
from NAVSBA OP4, Volume
2.
?ifth
Revision
summarizes primary concerns:
‘~Special static protective grounding procedures ● re required aboard
ship only during assembly/disaaoembly~ checkouts ●nd semicing of
weapona. In loading of weapons aboard aircraft, static protection im
considered ●dequate
if iumwdiately prior to removal of the shorting
plugs or dust covers and racking, the ●ircraft, weapon, ●nd personnel
must be at
●re at the same potential. Prior to unloading, personnel
the same potential as the weapon and must replace shorting plugs or
dust covers over contacts
prior to removal of weapon. In ●ll pbaaes of
8towage and operation, static protection i8 considered adequate
provided all firing circuit contacts are protected by shorting plugs or
dust covers. or firing circuits are ●lectrically out of line with the
electro-explofiivedevices (EED8) and the EED leads ar~ shorted to the
EED case (eg. EED lead6 and case are grounded to the weapon
ckin), or
the EED can safely withaitand25 kV between c~me ●nd bridge wire.
Unlese it is stated othewise
in
the
technical
manual or OP for the
individual weapons it may be assumed that ● weapon incorporate- on~ of
theme features and therefore needa no grounding during #hipboard
otowage.‘i
3.4 ~
Varioua circumatancea will ariee that will not
allow conformity with the Situations that have been prwioualy
described.
An
obvioue case is that which ariaes during winter weather
when it may not be p08gible~ because of ice or snow, to ground aircraft in the normal manner. In these
circumstances it become6 even more important
to ●nsur~ that bonding
requirements
between aircraft and refueler. or aircraft ●nd MEPP ● re met with ●ven more care.
It should be rcmmnbered that during the fueling process, static voltages are being
generated and accumulated continuously. and only the bonding cable provides ● meana
of keeping thi6 static voltage buildup under control, If the bonding wire is
attached to a painted eurface on the ●ircraft. the accumulated static voltage being
built up within the fuel tank eventually finds some point to arc over. Hopefully,
other factors which would contribute to ●n explosion are not present. It in
important to remember that during the r~fueling
operation fuel vapors ● re beinB
forced out of the fuel tank by the incoming fuel. The ponition and concentration
of the fuel vapore depend entirely on the wind circulation around the aircraft
which
is
completely
unpredictable.
235
?!IL-HDBK-274(As)
1 November 1983
Should refueling be accomplished from drums.
3*4*1
~
bladders, containers, or other ●ourcea~ the same grounding and bonding precautions
are required. This may happen in an area vher~ snow and ice make it impossible to
ground; and it is imperative that the drums or containers be adequately-bonded to
the aircraft,
Any hose nozzle
that is inserted
into a drum must be bonded to the
removina the drum cap.
drum before
Any portable pumps that ● r~ used must be bonded
securely to the eystem and grounded if possible. Similar grounding and bonding
precaution- must be observed during any defueling operation into drums.
3.4.2
~
Static
chargee
are bled off a hovering helicopter
by use of a etatic
charge
grounding wand,
commonly known as a shepherds
crook.
In
constant
contact with an electrically
order to be effective. the wand must maintain
conductive portion of the airframe and ground.
Should contact
be broken ●ven for a
%bort time (ie, a few seconds)~ dangerously high voltagee (in the thousands of
volts) can build up.
3.4.2.1 The wand must be ●lectrically conductive and be able to ?Sbreak avaytt
if required without injury to the operator. In addition, the device must be
electrically insulated to protect the operator from shock. The wand recommended
for utre is shown on Naval Air Teat Ceuter Patuxent River drawing no. 2754, and itw
associated ground stake on drawing no. 2752. These devices are shown in figure
3-4. The ground stake is intmded for use on portable landing fields where no
permanent grounds ar~ available. The stake is driven into the earth ●nd the clamp
attached firmly to it. For shipboard use the clamp is affixed to a bare ❑etal
mooring eye, A similar procedure is used at land-based fields equipped vith
certified ground ●nd padeye. This syst~ has proven successful in trials and will
replace the makeshift systms now being used.
.
.
3.4.2.2 ~
Thin procedure irnurnedfor quick
refueling of helicopters. The grounding wand must be used to make contact with the
aircraft to provide a bleed-off path for the electrostatic charges. The clamp end
of the wand must be attached to a certified static ground point. The wand must be
in continuous contact with the airframe until the refueling hose ig attached and
are in place. The procedure is as follows:
all ground/bond
wires
a.
b.
c.
Attach wandls clamp to certified static ground.
Make contact with helicopter frame or cable using grounding wsnd
hook.
Attach
fuel hose to helicopter cable.
3.4.2.3
The RAST systmn is
presently used only for the SH-60B (LM4’PSMKIII) helicopter system. The grounding
wand (shepherd’s crook) must be used to maintain continuous contact between the
deck and the aircraft until the RAST cable is secured to the aircraft. At t.’at
time.
the cable will provide the required conductive path to maintain the static
charge at a safe level.
3.4.3
In order to reduce turnaround time~ a
refueling procedure may be undertaken while engines arr operating. Here again, it
i8 mandatory that the aircraft be grounded and bonded a6 required for normal
servicing.
236
)
MIL-HDBK-274(AB)
1 November 1983
—
MIL-HDBK-274(AS)
1 November 1983
.
.
3.4.4 ~
Similar
precautions are required to ground ●nd bond the aircraft during water. oxygen. and
hydraulic aemicee. Where metal hoseo are used between oxygen or nitrogen cart ●nd
aircraft~ bonding in unnecessary.
)
3.4.5
In areas where nO approved etatic or pover grounds
=ists metal rods may be driven into the ground at suitable points adjacent to the
propomed aircraft parking poeition. For tmporary grounds that may be used for
some period of time, these rods should be approxi~tely 8 ft. long and 0.875 in.
in diameter. Care must be taken that the rod is not driven into a place where it
will damage underground cervices.
3.4.5.1 For aircraft operating in the field, a t~porary ground may be obtained
by driving a metal rod approxi~tely 3 to 4 ft IOng
and 0.5 in. in diameter into
the ground adjacent to the parked aircraft. This usually provides an ●dequat~
$tatic ground. The quality of the ground de~nda on”the type of soil ●nd the
mount of moisture available. The ground resistance can be improved by ●aturating
the area with water.
3.4.5.2 A temporary ground rod that ia in use for sme time should have its
ground resistance meamured on a frequent basis. The resistance should be less than
10,000 ohms. If it ig not, consideration should be given to driving additional or
longer rodn in order to reduce ground rernistance.
3.5
The following ● re excerpts from the Naval Safety
Center files. These narrative sections are reproduced here only to demonstratethe
actual types of probl~s that are encountered in daily fleet
operations.
3.5.1 Narrative: *’WHEN A.Co AND D.C. POWER WAS APPLIED TO ACFT, ‘lWEMAINT
PERS RECEIVED A SHOCK FROM ~E SKIN OF ~E ACFT. TROUBLESHOOTING OF ~E ELECT
SYS REVLD TNAT EXTERNAL Ace DOCO pOWER ReCeptaCle COFfNONGROum WIRE NR P 49AON
MD MELTED INSULATION. OXIDIZATION AND CORROSION VISIBLE AT THE TERMINAL ON THE
.,iCFT
SKIN WAS THE O~y APPARENT RMON
FOR OVEmEATnGo
ALL CONNECTIOtlSWERE
Sl?CURE.$l
Comment: Prior to any maintenance action, aircraft must be ●ppropriately
grounded.
3.5.2 Narrative: ~lDURING TURN AROUND IIVSPPLANE CAPTATN APPLIED ELECT POWER
!JTILIZINGTHE FLIGHT LINE ELECT DISTRIBUTION SYSTEM. UPCNlCONTACTING AIRCRAFT,
?LANE CAPTAIN RECEIVED MILD BUT DEFINITE ELECT SHOCK. ELECT POWER WAS SECURED.
WATER WAS STANDING ON u
~ A RESULT OF WEA~ER CONDITIONS CONSISTING OF LOW
OVERCAST AND RAIN, INVEST BY PUBLIC WORKS ELECT SHOP PERS REVEALED BROKER
GROUNDING PLIE WHICH PREVENTED ~E CABLE FRM ACHIEVING PROPER GRWND.
THIS
“INCIDENTReemphasize THE NEcEssIfl FCIRpRopER ~DLING
AND MAINTENANCE OF PLIGHT
LINE ELECT POWER DISTRIBUTION SyST~ IN ORDER To AVOID SERIOUS PERSONNEL INJURY,
ESPECIALLY UNDER ADVERSE RAMP CONDITIONS.*!
Comment: Emphasizes need to inspect grounding hardware.
238
I
MIL-HDBK-274(AS)
1 November 1983
3 .5.3 Narrative: ~~A,FTERSHUTDOWN FM FLT, ORD MAN BEGAN PROCED FOR LOADING MK82
PRACTICE BOM%S ON UTBD IUCKS. AFTER COMPLETION OF JETTISON NIL CKS, JETTISON
CART WAS BEING INSTLD IN PORT OUTBD STA. AS CAP AND CART WERE BEING INSERTED INTO
BREECH, CART EXPLODED. INJURY TO ORD MAN IHVOLVED WAS SUPERFICIAL AND THERE WAS NO
DAM TO ACFT. IMMED AFET INCDT, ORD INVOLVED CKED BOTH CKPTS TO ASCERTAIN JETTISON
SW POSITION, AND STATED BOTH WERE IN THE OFF/SAFE POSIT. ECWEVER, ACPT WAS
UNGROUNDED. THE MOST LIKELY CAUSE OF INCDT WAS TRE FAIL OF ORDNANCEMAN TO GROUWD
ACFT PRIOR TV EXECUTING LOADING PROCEDURES.”
Comment: The next ordnance man may not be so lucky.
3 .5.4 Narrative: ~~ACFT WOULD NOT ACCEPT EXT DC POWER FOR START. UPON REXOVAL
OF DECKING PLT SIDE, DISCOVERED DC EXT POWER RECEPTACLE GROUND LEAD WAS NOT
ATTACHED. FURTHER INVEST REVLD GROUND LEAD HAD BURNED A HOLE IN MOUNTING AREA,
THUS FREEING THE LEAD. BELIEVE ATTACHING BOLT WORKED LOOSE OVER A PERIOD OF TIME
AND CAUSED POOR CONNECTION. ANY LOOSENESS COUPLED WITH EXCESSIVE HEAT GEN BY HIG?l
CURRENT CAN RESULT IN THIS SIT.~~
3.5.5 Narrative: “WHILE PERFORMING BEFORE START CHECKLIST WIT’REXT D.C. PWR
APPLIED, CREW NOTICED SMOKE COMING FROM BENEATH PLTS DECKING. EXTERNAL WR IMMED
SECURED. T/S REVLD LOOSE GROND WIRE FOR DC EXT PWR RECEPTACLE. REPLACED GROUNDING
WIRE. ~t
3.5.6 Narrative: *IJUST BEFORE LIGHT OFF, ON START OF NO. 2 ENG, PLT SMELLED
ELECTRICAL FUMES AND NOTICED SMOKE COMING FROM UNDER HIS DECKING. HE SHUTDOWN BOTH
ENG AND SECURED ACFT. TROUBLESHOOTING REVLD DC EXT PWR RECPT GROUND WIRE LOOSE,
BURNING THRUGH ATTACHING STRINGER.9~
Comment: Para 3.5.4, 3.5.5 and 3.5.6 are typical of many reports and illustrate
not only the nee+dfor conBtant vigilance but the serioue consequences
that poor maintenance will cause. Any aircraft fire, especially onboard
a carrier, can be disastrous.
V~OR w~ OBSERV~ IN ~E STBD ~~
~L.
3.5.7 Narrative: f?~lLE DE~~lNG,
INVEST REVLD ALL FOUR ENG HRD BOTTLES HAD DISCHARGED. TRE FOUR PRIMARY CAR’rRImES
WERE EXPENDED. STATIC ELECTRICITY BUILD-UP CAUSED BY IMPROPER GRND OF FUEL TRUCK
TO ACFT. THE FUEL TRUCK TO ACFT GROUNDING WIRE WAS CONNECTED TO THE LANDING GEAR
SCISSORS STRUT, VICE THE GROUNDING KNOBS PROVIDED ON THE FORWARD SIDE OF TNE
LANDING GEAR. THIS SCISSORS STRUT IS PAINTED AND POSSIBLY COULD HAVE CAUSED AN
INPROPER GRND. PROPER GROUNDING PROCEDURES HAVE BE~ STRESSED IN TRE CM’Do MATNT
ERROR SQD.*~
Comment: This illustrates not only the need to make sure that the bonding cable is
attached to a clean metallic surface but the need to do an even better
job of atreasing these important requirements.
3.5.8 Narrative: “WHILE TROUBLESHOOTING A FUEL QUANTITY DISCREP, ELECTRICIANS
AE2 SOUCHAK, RECEIVED AN ELECTRICAL SHOCK WHILE HANDLING A CANNON PLW IN FLAP
WELL. INVESTIGATION REVLD THAT ACFT WAS NOT GROUNDED (NOR REQUIRED TO BE).”
Comment: Cannot agree with the comment “(nor required to be).”
requirements should be rewritten.
239
The local
.——
.
MIL-xDBK-274(AS)
1 November 1983
3.5.9 Narrative: ~~WEILE FUELING FOR ~INING
FLIGHT, LIGHTNING STRUCK IN CLOSE
PROXIMIn TO AIRCWT
AND FUEL TRUCK. OF TM! TWO CREWHE?tBERS FUELING TW! ATRCMFT,
ONE WAS RNOCKED TO THE GROUND AND TEE OTIU!RLEFT DAZED BUT STILL ON HIS FEET.
‘IIIE
DRIVER OF THE FUEL TRUCK WAS APPARENTLY UNAFFECTED, THE FUELING OPERATION WAS
SECURED AND THE CR~mS
WERE TAKEN TO THE HANGAR AREA WHERE CORPSMEN CONDUCTED
AND INITIAL EXAMINATION, THE CRFNMEKBERS WERE SUBSEQUENTLY TRANSPOR~ TO ~E
MEDICAL CENTER AND LATER RELEASED WIT?!NO APIUR~T INJURIES. B~AUSl? ACCEFTED AND
PROVEN SAFE= PROCEDURES WERE FOLLOWED, A TRAGEDY OF I~NSE
PROPORTIONS WAS
UNDOUBTEDLY AVERTED. ALTHOUGH THE SKY WAS OVZRCAST WITE S~
CUMULUS CLOUDS Il?TRE
AREAS, THERE WAS NO RAIN OR LIGHTNING ACTIVITY IffTHE AREA. AS A RESULT, ll!~
DRIVn ~
CR~~~S
ALL -E
SATISFIED THAT CONDITIONS -E
SAFE FOR R-ING
.
AT FIRST, IT WAS BELIEVED TMAT TKE AIRCRAFT HAD BE= STRUCK BY TEE LICHTNZNG:
30WEVER, A TEOROUGH INSPECTION BY QA PERS~NEL REVEALED NO MMACE OR OTWER
Indication ymT 3xE AIRCRAFTSUSTAINED A DIRECT HIT OR CONDUCTED m
poRTIOW m TRE
CHARGE . NO DAXACE TO IWE FUEL TRUCK WAS IN EVIDENCE OR IATER REPORTED BY T’RE FUEL
FARn ,
FOLLOWING THE LIGHTNING STRIKE, IT WAS NOTED THAT TYIEGRCX7NDIMGWIRE IIAX)
NUMEROUS BURN SPOTS AND WAS SMOKING. FURTHER INSPECTION OF THE GROUNDING WIRE
REVEALED THAT IT CONDUCT~ A SUBSTMTIAL
ELECTRICAL CRARGE AS EVIDENCED BY
DISCOLORED WIRE, CRyST~Xz~ ~TA.L, MD ~L~
wL~R
COATnG . DIJRINGTRE ZNZTIAL
ElW41NAT10N BY comm,
ONE OF THE CRPWMZMBERS COW+LATNED OF A T2NGL2NG SENSATION
IN HIS RIGHT ARM. SUBSEQUENT INVESTIGATION REVEALED THAT HE WAS IIOLDIIQG
ON TO lWE
TUELING NOZZLE AT THE TIME OF THE STRIKE. THE OTHER CREWKEHBER 1NITIALL% HAD
SLURRED VISION FOLLOWING THE STRIKE. IT IS BELIEVED THAT TliISWAS FROMBLYCAUSED
BY HIM HITTING HIs HM
ON ~E UNDERSIDE OF T’BEWING ROOT AT Y71ET=
OF THE
INCIDENT. AFTER TIIOROUGHINVESTIGATION BY TllEAVIATION AND GROUND SAFIH’Y OFFICER,
IT WAS DEmmINED THAT uL APPLICABLE DIRECTIVES AND RUUUTIONS WERE STRICTLY
ADHERED TO BY ALL PERSONNEL AND COMDS
CONCERNED AND AS A RESULT, ?URT’RER
SUBSTANTIATES mE VALUE OF pRopE~y GROUNDING mE AIRCwT
AND FUEL TRUCK DURING
‘FUELINGOPERATIONS.?? This saya it all - it is up to you to READ ANTI liEXD!~~
Comment:
None required.
3.6
Ground
resistance measur~ents should be taken at periodic intervals to ●nsure that these
measurement are made during different seasons over a period of yeara. A 15-month
interval ia rec~ended,
although local site conditions may dictatt other
“I,:aaurement
intenala~
3*7
In ●ll of the prwioualy
mentioned grounding procedures and considerations the receptacle ia the preferr?d
method of connection. Care must be taken to ensure that the receptacle is in good
condition. Any evidence that the mating connection is loaae indicates that th~
receptacl? ia defective and it must be replaced. Periodically, all receptacles
m~.~st
be inspected and their resistance to the aircraft structure should be measured
and found to be lese than 0.1 ohm. An MS 3493 plug should be ineerted in the
receptacle and found to be firmly seated. The pull required to withdraw the plug
should be between 8 and 14 lb. A pull of leaa than 8 lb indicatea a weak or
damaged receptacle: a pull exceeding 14 lb may indicate a corroded receptacle. In
either case, the receptacle must be replaced. Additionally, the complete cable
must be maintained in good electrical condition.
CAUTION: Use of alligator clips or braided panel strap to ground or bond
aircraft and support equipment ie prohibited.
240
MIL-EDBR-274(AS)
1 November 1983
If ● grounding receptacle io not ●vailable, ● approved grounding cable
3.7.1
constructed in accordance with MS 27574 =at be used. Carp must be taken that th?
clamp-type connectorO if unede conforms to ML-C-83413 ●nd must be checked for weak
opringt deformed or ruoty jwss or ●ny other defect which would prevent ● good
connection.
3,8
following list of military specification sheets is included for
The
reference pmrpoaes.
MS27574
Cabl~ Configurations, Grounding
US3493
Connector, Plug and Csp Electric. Grounding
MSO090298
Connector, Receptacle. Elec!tric,Grounding
MS33645
Receptacle, Grounding. Installation of
US25083
Jumper Assembly, Electric Bonding ●nd Current Return
MIL-C-83413
MS25486
Conncctor~ Plugs Attachable, Ext. Electric Power, Aircraft
115/200 volt 400 hertz
MS25488
Connector. Plug, Attachable, Ext- Electric Power, Aircraft,
28 Volt DC Operating Power
lM25487
Connector, Plug. Attachable. Ext. Electric Pwer. Aircraft*
28 Volt DC, Jet Starting.
241
MIL-IIDBK-274(AS)
1 November 1983
SECTION 4
This 6ectio~ provides theory, background, ●nd information necessary
to undermtmd
the rationale behind the requirements for ●ircraft 8rounding ●nd binding.
Theory
and equations aaeoeiated with both eltctroatatic charge generation in aircraft ●nd
grounding ●ffects are diocuamed. The different ●ircraft scenarios or ●ervicing
eituationn are introduced with emphaais on th~ hazarda that can be ●ncountered.
401 ~
Static ●lectricity, by definition ~telectricity ● t
rests” consists of opposite electrical charges that are usually kept ●part by
iwllators . Potential difference involved may amount to thougands of volts.
Xowever, the flow of electricity during generation ●nd ●ccumulation is small, in
the range of millionths of m ampere. A priwry
manifestation of static ?lecLricity is the discharge or cparking of the accumulated charg~s. Static electricity is generated by the separation of like or unlike bodies.
Electrostatic
charges, positive and negative, always occur in pairo. They become ●violentwhen
theme paire, having been in contact with each other. are separated. For significant potential to be developed, the bodies holding the charges must become. and
remains insulated from each other. Insulation may occur through complete phyoical
reparation of the bodi~s
or because
at least
one of the bodies is an in9U18tOr.
4.2
this manual:
a.
b.
c.
d.
The following aircraft evolution or ecenarios are considered in
Stores handling (including ordnance)
Maintenance (flight line and hangar)
Fueling
Parked
2otential hazard6 considered during each scenario are:
a.
b.
c.
d.
e.
Static electrical shock to personnel
Power 8y6tem electrical shock to personnel
Ordnance misfire and/or inadvertent ordnance or stores release
Fuel vapor ignition
Damage or upset to electronic subsystems
4.3 ~
The sourcp mechanism and source magnitude of the electrical
energy is critical in aGoessing the possible occurrence of a hazardous situation.
‘I’he
following energy source6 are to be considered during the aircraft evolutions of
stores handling, maintenance, fueling. ●nd ●ircraft parked:
a.
Static
Triboelectric
● Induced
● Friction
Power
● Ground fault
● RF electromagnetic ●nergy
● Lightning
●
b.
242
)
UXL-EDBX”274(AS)
1 November 1983
4.3.1 ~
The ststic sources listed ●bove are
in the following paragraphs.
defined and evaluated
4.3.1.1 ~
One type of charging mechanism that can creste
dangerous voltages on ungrounded aircraft is triboelectric effects. These ●ffects
are generally aaaociated with the buildup of ntatic chargee on an aircraft in
flight. High static voltages. however, can recult from the interaction of various
materials etriking a parked ●ircraft. Vind-blmrn snow or dust particles ● re the
usual objects responsible for this charge ●ccumulation. commonly called precipitation static or p-static.
4.3.1.1.1 A conse~stive estimate of electrical current for ● moderate windblown dust cituation is 30 microampere (PA). In an ungrounded aircraft. this
current flows from ●arth to the snowp dust~ etc. via the tires and airframe. Thus*
the potential between ●irframe ●nd ●arth is determined almoct entirely by the tire
resistance. A worst-case value of 40 megohms (Ml) for tire resistance is used to
compute an airframe potential of:
V=XR=
(30#A)(40
I’fs2)= Izoov
4.3 ,1.1.2 These chargea will ●ccumulate until a sufficient time to discharge
paeeed or a person touches the aircraft. Twelve hundred volts (1200V) exceeds
parameter for nonlethal shock to personnel. ●nd could cause a reflex action
resulting in injury to personnel.
haB
4.3.1.2 ~rod
~
Electrical stems involve the relatively slow movement
of heavily charged clouds which set up ● n ●lectrostatic field over a large area of
the earth’s surface belw the cloud. The presence
of ●n ●lectrical field between
● n active storm cloud syetem and the earth results in large induced charges on
parked aircraft. As shown in figure 4-1, the negative charge in the cloud attracts
● pomitive charge from the earth onto the aircraft via the tires. This charging
usually occurs at a relatively S1OV rate which results in relatively emall current
flwa that cauee no damage to the aircraft. If ● person ia in contact vith the
plane throughout the charging period, ie, ● s the charged cloud moves -lowly
overheado he will probably feel no effect.
4.3.1 .2.1 The situation becomes ● potential hazard if a sudden change in thr
~lec?ric field takes place (ego a distant lightning strike discharging the overhead cloud). The earth~s surface neutralizes more quickly than the ungrounded
aircraft (due to the capacitance of the ●ircraft
●nd the high resistance of the
tires), resulting in potentials up to 60 kilovoltc (kv) from airframe to ground. A
person in contact with the aircraft during this change in the ●lectrical field acts
● s ● reaietor connected to groundo facilitating ●nether path to 8round for the
●ccumulated charges. (See figure 4-2.) This parson will probably feel ● shsrp
shock~ the severity of which will depend on the extent to which the aircraft was
originally charged. The current shock can result in injury to personnel in two
different wayn:
●.
b,
Involuntary reflex movements which can cause fatal or 6eriou8
injury clueto ●econdary ●ffects, such ● s falling~ and
Electrical ●ffects which r~sult directly in injury.
243
- ...——
MIL-EDBK-274(AS)
1 November 1983
—
--——
—
——
---
---
---
--—
—
-—
.+ +++
+
+
++++
+
++++++++++++
+
+
S031.71
FIGURE 4-1.
——
—
—
●
—
—
—
—-.
—-
●
☞☞☞☞
●
●
☛☞☛☞☞☞☞☞☞
☞
●
☞
●
☞
☞☛
5031.72
FIGURE 4-2. ~
244
MIL-HDBK-274(AS)
1 Novemb@r 1983
4.3,1.2,2 A par80n in contact with an aircraft charged by induction to 60 kV
@ould discharge 9 joulgo (J) of ●neruy from the ●ircraft.
usl/2
#
=1/2 (0.005 Pf)(60 kV)2
89J
This level well cxcoods tho thr~shold valut for lethal Aock
To furthtr
analyce potential
●nd could be fatal.
hsmrdo~
t=Rcln
where t = time to reach E, after removal of source
R=
●ircraft resistance to ground (Q)
C = aircraft capacitance to ground (f)
Ei = initial (source) voltage (V)
E
= safe voltage level (V)
s
U#ing the ungrounded aircraft resistance of 40 MSk ●n ●ircraft capacitance to
ground of 0.005 microfarad (#f), ● safe voltage limit of less thm 30V. ●nd 60kV
the initial voltage
t = (40 KZ)(0.005 pf)ln
●s
(6&)
= 1.52 sec
discoordination (fibrillation) threshold levels have time durations as low ● s
0.2 second (see). ● fact that makes the 1.52-sec discharge time very dangerous ●nd
umcceptable.
Heart
4.3,1.3 ~
Static electricity im 8enerated when certain
matmiala rub
together. During ouch close moving contact between two materials. oxw of the
~terialc is depleted of electrons causing a surplus in the secondo The magnitude
of the static electrical char8e thus produced depends on the materials involved ●nd
on the amount of humidity present during such friction. With synthetic materials
(such ● s nylon) undergoing
friction in ● cold dq Cli-te.
the ●ffect iS Ureater”
4.3.1.3.1 Static electricity in generated on clothing by friction@ ●specially by
the action of ramovin8 gamento.
There
is ●lso ● contiguous generation of charges
in the gazmeats of ● moving clothed per-on. The total amounts of charge at any
time will depend on the rate of charge production ●nd the rate of charge decay. If
● person rubs ●gainst ●xternal objectso chargetican be produced on the outside of
the garments; otherwise. the charges will be produced within the clothing system ● s
shown in figure 4-3.
245
MIL-RDBK-274(AS)
1 November 1983
)
+
+
NYLON
PARKA
+
WOOL
SWEATER
+
5031.73
FIGURE 4-3.
4.3.1.3.2 It is generally considered that all parts of the akin are sufficiently
moist to allow only negligible amounts of charge to be formed between the skin and
the garment next to the akin. Provided the person does not remove any garments,
the only effect of the charged clothin can be to cause an attraction between the
Iayera (since opposite charge6 attract! or for the clothing to cling to the body.
4.3.1.3.3 However, if a person removes the outer garments (as shown in figure
4-4). a charge of up to 27,000V can reside on the outaide surface of the newly
expo8ed clothing. The positive charge on the wool sweater and the negative charge
‘onthe parka are available for “static effects.ft The opposite charge6 on the
.aweaterand parka may ●aBily produce a apark from one to the other.
4.3.1 .3.4 The 27-kV value ia used herein aa representative of the worst-case
static lectricity friction hazard levels produced by servicing personnel. Using
u= 1/2 CV with C = 500 pF (picofarads) for body capacitance* the amount of
available energy is 0.18J. This is well above the thre6hold levels for fuel vapor
ignition~ component damage, EED ignition, and relex action ohock.
●
4.3.1.3.5 ~
During the fueling proceag, the passage of fuel from the
supply vehicle through the fueling hose to the aircraft provides the mechanism for
a recurring electrostatic energy source. The friction effect between the moving
fuel and fuel filter, hose, and other surfacea results in charge separation and a
consequent buildup of electrostatic chargea. (See figure 4-5.) Since fuel is
normally an excellent insulator, separated charges are easily removed by the
tloving fuel to a diotant location. If no electrically conductive return path ia
24b
MIL-HDBK-274(AS)
1 November 1983
NYLON
PARKA
5031.74
FIGURE 4-4.
~
FIGURE 4-5.
247
XIL-HDBK-274(AB)
1 November 1983
availsble, the charge accumulateon metallic surfaces ●nd reprmeuts ● hi8h
AB the ●ccumulation of charge contiuueas
sufficient
●lectrical
potentisl ●ersyB
potantial is 8m.rsted
to cauoe ● ●rc ● cross insulating
basricra.
ThoBQvolta8ea
build up within tha ●ircraft fuel tank ●nd roprasent a @arfou@ huer~
If them
voltasoa
●e
owr to points of lower potantial vhon tht A$ht fwl-air
vapor
mixtuto i. pr.mato
●
●xplodon vill occurO Bonding the ●ircrfift frame to the
fual Dupply vohiclc provid~a
a method of di~sipati~
thaso hith voltag~s. Bondin8
flaasnot prwont
the saneration
of high voltat~s
within th, fuel hom ●nd the fuel
iaak~ but provid.m 8 return path for the ●ccumulated
cha~os ● t oontaet 48 made
with tha incido fuel tank mrfsco.
Naval Xosemch Laboratory (BRL)B Qoman Air FOrCOB Unit.d
(UUY ! , ●nd others hwe provided
data on the magnituda of volta80a
and cursent which might be ●ncountered during the fueling process. Field strengths
4,S,1,3,6
Btatca
Air
Dtudfoo b
?orcc
by this process may rsnge to 500 kilovolts/meter (kV/m); thuso ● t s
centimeter diatameee ● 5 kV potentisl may be present.
The 500 kV/m field in
aarmelly confinod to the fuel tank interior. However. depending on the locations
of the separated ehsrtoo ●nd the degree of ●lectrical isolation of the ●ircrafto
fields of this intensity
may ●ppear on the exterior ● s charge bleed-off occurs.
The resulting voltage on the exterior of the tenk is dependent on the physical configuration ●nd could reach breakdown or srcing level near sharp edges.
Measurements ●fter fueling
●ircraft have provided values of 2.5 kV.
%merated
4.3.1.3.7 A percon in contact
with ●n ●ircraft chsrged by induction to 2.5 kV
could discharge 15.6 millijoules (mJ) of energy from the ●ircraft,
●1/2 (0.005 BF)(2.5 kV)2
I
Thio level exceeds the threchold value for reflex shock reaction.
To further ●nalyze potential hazards:
t=RCln
()
‘i
8:
where t = time to reach E, sfter rmoval of source
R =
sircraft
resistance
to
8round (fl)
c = ●ircraft capacitance to ground (f)
Ei = initial (source) voltage (V)
Em = safe voltage
level (V)
1.
248
MIL-HDBK-274(AS)
1 November 1983
Using the ungrounded aircraft re8i8tance of 40 ML ●n ●ircraft capacitance to
ground of 0.005pF. a #afe voltage limit of less than 30V. and 2.5 kV as the
initial voltage.
t
=
(40
~)(0.005pF)ln
= 0.88
~2.;okV)
sec.
Heart discoordination (fibrillation) threshold levels have time durations as low as
0.2 sec. which makes the 0.88-eec diecharge time very dangerous and unacceptable.
4.3.2 ~
Various types of electrical power. such as 115 volts. alternating
current (vat), 28 volts. direct current (vdc)~ lightning, ●nd rsdio frequency (rf)
The term power used in thin context
are discussed in the following paragraph,
aasumes ●lectric current flow measuring amps, in contramt to static ●lectricity
whose current flows typically, is in the range of thousandths of ●n -Pere.
The purpose of the equipment grounding conductor in
4.3.2.1 ~
an electrical oyat- is to provide a path for current to flow under ground fault
condition. The equipment ground path must have efficiently low impedance to
limit voltage rime and to pemit ample current to flw.
This ●nsures rapid
operation of the overcurrent device when a ground fault occurs. If a ground fault
occurs and the overcurrent device operates slowly or not at allD the result can be
electrocution of personnel, fire~ or destruction of equipment.
4.3.2.1.1 Ground power fault occurs when the high voltage side of an external
power connection iB brought into contact with the airframe. The main reaeon for
thie occurrence in an internal miawiring of the connector plug or backward
attachment of the connector. Component failure has ●lso been partly responsible.
The beat way to avert aa many problemn ● a possible ia to carefully ●xamine the
connectors for any evidence of damage prior to connecting to aircraft or chasaio
receptacle. These connectors are particularly prone to damage because of the
nature of their function. repetitive connection, and disconnection under all
conditions.
4.3.2.1.2 Due to differences between power ●nd static energy sources, a ground
point with ● much lwer impedance to earth is needed. A distinction must be made
between the power or maintenance ground (leas than 10 ohms) and the static ground
{les8 than 10.000 ohms).
4.3.2.1.3 When the ●ircraft pwer ia being ●upplied by a Mobile Electrical Pwer
Plant (MEPP). the problem is that of parallel ground paths. Whether an enginedriven ground power unit (GPU). ●lectrical-driven units Flight Line Electrical
Distribution syst~s, (FLEDS), or deck edge power is u~ed, ●ll systems face the
~ame problem. (See figure 4-6.)
4.3.2.1.4 The direct current (de) is 28V ●nd is a two-wire syotrsnwith a
positive and negative. The negative of the system is connected to the aircraft
etructure and cart chaoaia through the connector. The alternating current ie 115V
ac~ 400 hertz (Hz) and is a four-wire system conaiating of phaBe A, phaae B, phaoe
C, and a neutral (N), The neutral wire ia connected to the aircraft structure ●nd
cart chassia through the connectors. Aa the figure illustrates, the purpose i8 to keep the aircraft at ground potential but ●lso to let the circuit breakers operate
249
. . .—
?fXL-HDBK-274(AS)
1 November 1983
)
ER
CERTIFIED
?owER GROUND
CADLE
MS 26407/s
iLcssTHANIOOItMSI
ELECTRIC MOTOR OR IVW
CONNECTOR
Ms2mm
1
AI RCRAVT
STRUCTUn E
.
E::z:Lm
.EPPINC2NNC1K
CABLE
MS27674
1
I
RuBOER TIRES—
4
\
COt#iECTOR
MS 2S4S7/B
CERTl FIf D2.7ATIc
GROUNO
(LESS THAN 10,000 OHMS I
BONOING
CABLE
*.*?.?
DIESELENOINE DRIVEN
FIGURE 4-6.
properly. Bonding the ●ircraft to ground pover unit
(CPU), using a suitable
grounding cable. will help ●vert d~ngerous situations. When the fault occurs, the
wtire ●irfrane ia at power line potential. 120V to 220V ●nd may be capable of
Jupplyimg currents ● s high ● s 200 emps. Power introduced from m external tource
●rth
complicates the selection of ●n earth return limit. The maximum allowable
resistance is dictated by the requirement that sufficient current
flow to trip
power circuit protective devices under earth fault conditions. The trip time (time
to open circuit. ● function of the earth psth resistance) for power faults must
requires that the earth path resistance be
81OO be considered. Personnel safety
low ●noush to ●11OV a 500% to 600% overlmd current with a trip time of ●pproximetely 0.2 sec. Thus ● 120V. 50 ~p sewice requires ●n ●artkspath seturn resistance of 0.5 ohm for safety
under power fault conditions. Locations which do not
0.5-ohm ●arth resistance ● re limited in the safe maxi=
load which can be
provide
haadled. As ● exemple, ● 120v source with 10 ohms in the return path ●nd ● 600%
werload trip level of 0.2 sec retponse time is limited to ● s~mice current of:
=
1“~
R
[120)
overload
= 2A
(10) (6.00)
I
250
MIL-HDBK-274(AS
)
1 November 1983
Unfortu~tely, very few ground points ● re ●ble to ●eet a 0.5 ohm or less require
A more practical value of leas than 10 ohm for power grounds is reccnmaended.
4.3.2.2
Todayts enviro=ent ha- many unintended side
used in conjunction
with naval flight operation. Of concern ● re those high power communication and
radar transmitters which may be located near parked ●ircraft. The beat ●xample of
thi$ situation is the carrier flight deck. which probably containa the highest concentration
of ttammitted rf ●nergy to be found on -y bane from which ●ircraft
operate. Although high power communication ●nd radar transmitters may be found ut
greater distances from parked aircraft at ● shore station, an ●ircraft may be
affected by ● n ●djacent aircraft whose onboard communication system or radar
tranemittera are being tested.
●ffects caused by radio frequency (rf) transmitting dwicee
4.3.2.2.1 The principal problem in the amount of rf ●nergy which is induced into
the aircraft frame and circulating on the aircraft skim. This quantity or level of
rf energy i# greatly affected by the position of the aircraft relative to a
particular rf transmitter, the power output of that transmitter. and the actual
frequency of the rf energy being transmitted. It ie further affected by the ●ctual
location of any connections between the ●ircraft and ground (deck). Where the
position of one ground may have a significant effect on the induced current, other
ground connections from different locationa on the aircraft to other locationo on
the deck may not have the same effect. Any eximting aircraft grounding scheme
should not be altered in an effort to provide the aircraft with additional protection against rf energy. If the ground connection is broken while the rf
transmission is in progress. an ●lectric arc may be drawn out. Thio is an
important fact to note. If an arc is produced while disconnecting a ground. the
source may be rf ●nergy, caused by a local transmitter and the current flw can be
high. (A power line short circuit to ground may also produce an arc when the
ground is disconnected.) If. on the other hand. ●n arc is drawn while a ground is
being attached to the aircraft, the 8ource ie etatic ●lectricity and the current
flow will be light.
4.3.2.2.2 RF arcing is not limited to aircraft only. In high rf fields. arcs
generally occur at the discontinuities in conductors (conductor meaning any metal
eurface). A discontinuity io any place where the nature of the conductor changes.
Examples of thin include gapa between metal surfacea ●nd placeo where the type of
metal changes or the thickness of the metal changea.
4.3.2.2.3 Another factor which has an influence on the occurrence of rf arcing
is the actual physical dimenmiono of the metal surface: Not all conductors within
an rf field are susceptible to arcing at their discontinuities. Objects which are
large with respect to a wavelength (several wavelength in each direction perpendicular to the line of transmission) tend to reflect the rf ●nergy and are less apt
to produce arcing. Objects which ● re long in one dimension but not in the other
tend to be a more favorable mite for arcing.
4.3.2.2,4
RF arcing can be separated into two categories: rf glow discharges
In rf glow discharges, a high minimum voltage is neces8arY
to maintain the diecharge. The voltage rises linearly to an ignition voltage of
350V to 500V. then decreases slightly after the current flow begins. The current
flow ceases when the field can no longer sustain the high voltage. Even at very
small separations between elements, a minimum voltage of 275V is necessary to
sustain the glow.
●nd rf arc discharges.
251
MIL-HDBK-276(AS)
1 November 1983
4.3,2.2.5 Conversely, Zf arc di~chargem ● re ~ust~imed at relatively IW
voltages. The wents leading to the forwation of the ● re plasma ● re similar to
those of glou discharge. Ewever. once the ● rc plama form. the voltage can
ummlly drop to as 10V as 30V without the ● rc ●xtinguishing.
4.3.2.3 ~
Lightning is ● discharge of ●~ospheric ●lectricity from one
cloud to another, within a clouds or from a cloud to ●arth. Table 4-I provides ●
is the
licting of lightning characteristics. The cloud to ●arth or ground strike
the direct
lightning strike. lhseto its lurge
type of discharge that produces
amount of energy and potential for destruction- the direct lightning strike is one
source of energy that can be very dangerous to personnel md ●ircraft. A direct
lightning strike can damage ●n aircraft ●nd its ●quipment. Voltages ● s high ● s SOO
kV and currents to 200 kilozmperes (k&) have been known to occur.
4.3.2.3.1 These high levels could puncture the aircraft if tbe skin is not suffi,%,i?ntly
thick or could pooaibly cause-localized melting. Damage to tbe ●ircraft’r
?l&ctronic equipment or ignition of the fuel tank could occur~ depending on the
l.~cationof the strike.
4.3.2.3.2 A pers~ in ~ntact with the ungrounded ●ircraft during ● direct
lightning strike riakn death or severe injury. For personnel who Wear communication
headsets the probability of occurrence and the severity of injury increase.
TABLE 4-I.
I
.
~
Characteristic
.
Specification
Types
Intra/intercloud
Cloud-ground
Positive
Negative
Potential
30-100 million volts
Current
20-200 kA (peak)
Pwer
101k nominal (peak)
Energy
5X108J nominal (200 lb 771T●quivalent per strike)
I
Extent
3-30 kndstrike (path is predominately horizontal)
Spectrum
Peak energy near 10 kEz. some ●bove 10 ~Z
I
Duration
Strike - 100 plJ
Flaah - 0.2 ●ec (1-20 strike.)
I
i
I
252
!
MIL-HDBK-274(AS)
1 Novemb@r 1983
4.3,2,3,3 A typical discharge between cloud ●nd ground starts in the cloud and
eventually aeutralice~ tens of coulombs of nesative
cloud charges. The total
dimcharge i. called s flash
●nd la$t8 ●bout 1/2 BQC. A flaah ia made up of various
discharge c~ponemts~ emons which ●n ●waue
of three or four Mh-cu=ent
Pul~e~
In the ideslised
occuro called strokes~
end a possible
conthairw
current Otase,
models ●lectricsl
otorm ceuse the clouds to ●cquire ● aesstive charge. The ●a*thO
or in this case the ●ircraft.
hes ●n oppoaitc
cherge ●nd Iightniw
occurs when the
●lectric potential overcomes the iaoulatiou of the ●ir.
4,3.2.3.4 The breakdovnwithia
the cloud produces what ic eslled ● stepped
the cloud ●nd heads twsrd
tlw $rounds
The leader
advances ia ● #tries
of rapid discontinuous
st~ps ●acb ●bout 50 meters (m) 10U ●id
separated by pauses of ●bout SOW. The luminous diameter of the ctepped lesder ic
between 1 ●nd 10 m, ●lthough it it thought
that
the leadez current
of ●bout 100
empa flows in ● ●men diemeter
core ●t lt8 center. The ●verage propsfption velocity is ●bout 1 m/s. It looks like ● column of light with brenches emanating from
the aide-. The8electric potential of the lesder channel with respect to the grouud
is ●bout -1x1O V. As the leader tip nears ground or ●ircraft. the ●lectric
field beneath it become- very large ●nd causes one or more upward-moving
discharges
which #tart the ●ttachment process. When one of the upward-moving diacharses from
the ground contscto the downward-oving leader. the leeder tiP ~B co~ected
to
ground or ●ircraft potential. The leader chennel is then discharged into the
●ircraft.
The height
of the ●ircraft ●ffecte
the probability
of this happening.
The taller the sircraft
the more likely it i~ to happen. Thus, by 10CSI1Y compresthere ●r~ more likely to be points where the discharge tskea place,
sing the field,
(See fisure 4-7.)
leader.
The
leader
starts
from
k<
,’,
.,
—
.
—
.’
4-, ‘J”’”u’j
.: ,
“%
-----—
--—
---..“-’h+.
$-K’-
—
++++
+
+—
+
“-‘%7
4-’+7
*+ G’k++=J4-2:
——
— ——
—-
%
“
,>’/, .
,.. .
-_
7‘
‘?2.&ig-
●
603175
FIGURE 4-7.
~
to ~
253
.
MIL-HDBK-274(AS)
1 November 1983
4.3.2 .3.5
Intrac~oud and intercloud lightning discharges occur between positiv~
~nd negative cloud charges and have total durations about equal to those of ground
discharges (1/2 see). A typical cloud discharge neutralizes 10 to 30 coulombs (C)
of charge over a total path length of 5 to 10 km. (See figure 4-8.)
4.3.2.3.6 Intracloud and intercloud discharges have not been studied as
extensively as cloud discharges to ground. and hence much less is known about their
‘Ietailedphysical characteristics. The charge motion for intracloud ●nd intercloud
discharges produces electric fields Vhoae frequency spectra have roughly th~ same
amplitude distribution as ●l?ctric fields produced by cloud to ground di6charge6
for frequencies below about 1 kHz and above 100 kHz. Between 1 and 100 kllz,the
ground discharge is a more efficient radiator.
4.3.2.3.7
Energy
l~vels
of near Strikes
can be sufficiently high to damage
t’
~ectronic equipment, again, depending on the location of the strike. Distant
lightning strikes and lightning from me cloud to another will ●lso charge ●n
Iircraft. Grounding will not keep these induced charges from accumulating on an
aircraft. but will reduce the amount of time required to bleed off the charge.
4.3.2.3.8
The most important par~eters of the current waveform are peak
current, rate of rise, total duratio , charge transferred, and action integral.
9
The units of action integral are amp sec which may alternatively be exprcased in
units of joules per ohm siDce the action integral is proportional to the energy
‘Dissipatedin a given resistance. (See figures 4-9 and 4-10.)
4.3.2.3.9
The charge
transfer, Q, is defined a6 the integral of the time-varying
current over its entire duration, or
~T idt (ampere-seconds or coulombs)
~
And is equivalent to the arPa beneath the current waveform as shown in figure 4-11.
Q=
4.3.2.3.10 The action integra] of a current vaveform is a meaaure of the ability
~,fthe current to deliver energy and is defined as the integral of the 6quare of
zhe time-varying current over its entire duration.
T i2
Jo
dt (ampere2-seconds)
4.3.2.3.11 Grounding an aircraft offers some protection against lightning, even
i direct strike. A major direct lightning strike usually is preceded by less
pcwerful leaders which determine the direction of the main strike. Grounds can
control the direction of the leaders away from the tires and consequently control
the direction of the main strike. In addition, if a direct strike occurs, the
~round wire may vaporize contributing to the conductivity of the ionized path. and
thereby minimizing leakage currents through nearby peroonnel.
4.3.2.3.12 Lightning discharge through an aircraft to earth i6 an extremely
variable phenomenon. voltages as high as 0.5 million VOlt6 and currents from 200
to 200,000 amps are cited in the literature. At such high levels, grounding will
not afford the degree of protection or confidence factor attained for static
electric protection. Nevertheless, a safety ground will aid in protecting p~r~onnel and equipment to some extent, especially for the lower energy 6trike6.
254
)
I
MIL-KDBK-274(M)
1 November 1983
___
--e’
-.- .
‘--i
--------
-----——
.
CLOUD
----
----.
—
---—
DISCHARGE
_-
.—
1
CLOUD
2
.&-
—
TO CLOUD
INTRA
--
., t
, +
.... + + +
,
+++
,,
;
.
.
.
***
~.
—
—--
-
(INTERCLOUD
—- -\.
..
——
DISCHARGE
IWITHIN
3
4
CLOUD TO GROUND
A CLOUD)
5
DISCHARGE(BUILDUP
.
FIGURE 4-8.
STRIKE)
~
6
PROCESSI
__
——
HIL+IDBK-274(AS)
1 Novcmb@r 1983
)
kA
I
200 --
4
~
d
100
I
1,5
40
t{microteconds)
S031.77
‘lGURE
4-9* ~
LOG
I
I
t
I
I
I
4
I
t
#
I
1
I
I
,
I
I
I
I
I
1
,
I
1
u
0
I
4
t
I
I
I
I
\
LOG W
60317s
FIGURE 4-100 ~
I
2%
r41L-HDBK-274(AS)
1 t+ovemb~r1983
i
t
I
T
6031-79
FIGURE 4-11.
4.3.3
~
IrIsummary, the levels of electrostatic ●nd ●lectrical energies
considered are given in table 4-11.
.
When energy sources are consid4.4 ~~?~~
ered in temns of voltage or current, the ●lectrical characteristic (ies tire
resistance to ground and airframe capacitance to ground) are required to #atablish
time duration and other parametric relationships (eg~ current to voltage and current or voltage to total ●nergy). Airframe electrical parameters interact with
charge generation mechanisms ●nd thereby establish the actusl hazard levels and
time duration for these hazards, Airframe capacitance to earth ●nd airframe
resistance to earth are most relevant. Capacitance establishes the total charge
due to a particular potential and the time factor required to dissipate a
stored
charge from a surface through a particular resistance. Resistance ●stablishes the
voltage associated with known current flovs ●nd the time factor for charg~ r@duction when the capacitance is known. Rsaistance was found to be the more variable
parameter.
257
MIL-HDBK-274(AS)
1 Novmbrr 1983
TABLE 4-II.
.
Le P1
Source
Voltage
Current
)
0.03 mA
Triboelectric
0.013
ti
Fuel flow
2.5 kV
Induced charge
60 kV
Friction
27 kV
Ground power fault
220 v
200 A
RF induced
No ●stablished values
No established values
Lightning
500 kV
200 u
4.4.1 The ability of a body to store ●lectrostatic charge is determined by the
capacitance of that body. The amount of charge that can be mtored on ● capacitor
is expreesed by the mathematical expression
Q = Cv
where Q is the amount of charge (in coulombs). C in the capacitance of the body (in
farads), ●nd V ia the voltage (in volts) developed between the Platec of the cavacitor, The rate at which the capacitor charges or discharges is-determined by the
electrical resistance, R (in ohms), through which the capacitor chargea or discharge (see figure 4-12.)
4.4.2 Aircraft in their normal environment have ●lectrical properties ●imilar to
resiutors and capacitors. The resistance is usually determined by tires, mooring
chains~ or static
ground straps. This is illustrated in figure 4-13.
4.4.3 Aircraft resistmce in affected by both the reaimtances of its tires ●nd
the runway surface and also by the contact between the tires ●nd the surface. Tire
reoiatance ia a highly variable par~eter. As a tire wears, its resistance increaoes due to the breaking of the carbon black chains.
4.4.4 The load on the aircraft
and the praasure of the tire affect the resistance of the aircraft by affecting the tirest contact with ground. Increasing tire
pessure increases resistance, and increasing load decreaaea resistance. Laboratory measurements have indicated tire resistances ● m high ● # 3400 HfL
4.4.5 Finally, the material of the runway ia a factor in the resistance of the
aircraft to the ground. Dry asphalt has ●n exceedingly hi8h resistance, while snow
and water on wrfacea decreaae the reaimtance. Field measur~ents have measured
total aircraft resistance to ground as high an 40 ML
t
258
MIL-HDBK-274(AS)
1 November 1983
R
++++4++4
+
b
c
ENERGY
sOURCE
v
-----
-
6031.48
++++++++++++++
..-
---
---
-——
+++++++++++++++
-—-
FIGURE 4-13,
——--
---
++
----
----
.
~
259
- —--
.
_.
—-—.
—
MIL-HDBK-274(AS)
1 November 1983
4.4.6
The capacitance of aircraft was found to be a consistent paramettr.
values of 0.002 to 0.005pF were meaeured over a vide range of aircraft types and
ground plane materials.
)
4.4.7
In addition to the charact~riatics Of the ●ircraft,
the values
of human
body electrical parameter art ne~d?d. Values of 500 pF capacitance and 50 to 1500
ohms resistance ar? representative values for descriptive/discussionpurposes. The
partinent @l@ctrical characteristics are aummariz~d in table 4-III.
4.4.8
ne rate at which a capacitor or an aircraft discharges is det~rmined by
its time constant and is given by the relationship
T=RxC
Yh.ereT is time in seconds. A capacitor can be aasumed to be completely discharged
after five time constants or ST. Aircraft capacitance ia a fixed quantity under a
particular parked configuration. Therefore, in order to reduce the discharge time.
the reaiaitancemust be reduced. Aircraft tires measured in the field have
have been meaeured as
resistances aa high aa 40MCL Aircraft capacitance values
Ueing the previous equation
high as 0.005pF.
T=
(40 x 106) x (.005 x 10-6)
‘r= 0.2 Bec
5T = i aec
4.4.9 Discoordination threshold levels of the huan heart action have time
durations as low as 0.2 sec. Thus, 1 sec for the aircraft to discharge is
unacceptably long. If, for exampl~, a maximum resistance of 10,000 ohms is
considered, the same calculation yields a capacitance discharge time of 0.25 ms.
This is well below the 0.2 aec critical value. Th?refore, it is necessary to
reduce aircraft-to-ground resistance by grounding the aircraft, thus bypassing the
aircraft tires and mooring chaina.
The third variable needed for analysis io the
4.5 ~
‘hreahold for injury or damage due to el~ctrical ●ffect$o
4.5.1
The minimum ●nergy threehold for ignition of fuel is 0.25 mJ.
4.5.2 ~
A level of 35 mJ ia the potential danger level during etorco and
ordnance handling. The ignition of electroexplosive devices (EED) in various
accuating mechanisms ia the most common danger area.
TABLE 4-III.
I
Characteristic
Specification
Aircraft capacitance
Aircraft resistance
Body capacitance
Body resistance
0.002 to 0.005MF
l.oKQto 40 t4fl
500 pF
50 to 1500 ohms
...-.
260
)
HIL-E.DBK-274(AS)
1 November 1983
4JBS
~
from shock;
●
~ere=e-~s~ible
.
b.
sources
of injury to persoaael
Imvoluntsry reflex movmenta which can result in injury due to
●ecoadary ●ffectsO 9uCh ● s falliago
Electrical ●ffects which result directly in injury.
4.5.4 Reflex ●ction ●ppears in the ● rea of 10 to SOmJ<l
to 3 mll ● cross 10.000
ohmo); ● repre~eat~tive
voltage
h ●pproximately
50V (30 mJ sad 1500 ohms). The
threshold level for potentially lethal ●hock was ●stablished
● s 30 vac ●nd 45 vdc
st energy levels of 600 mJ sc ●nd 1.35 J dc. ssmuming ● body resistance
of 1500
ohms●
4.5.5
~mt
~
The threh$old level for ●quipment damage is ●
function of dielectric breskdowa (high voltage effect),
high t-perature damage
whea directly
(high power effect). or ● combination of both. One mJ ●n cause up-et
injected into sensitive circuit-. Rowever, since direct injection is ualikely. ●
couplia8 factor of ●pproximately 10 is ●ssumed to ●stsblish ● minimm threshold of
10 mJ for the practical lower limit of sensitive equipmeat up-et.
Damage levels
sre taken sc 35 mJt comparable with ordaaace thresholds.
405~6 ~
In$~rYP
the lev’l@of
●lectrostatic ●nd electrical energies considerd are tabulated in table 4-IV.
4.6
The basic
purpose
of the prwiou- materisl of this ●ectioa has
been to ●stablish the data which verify or disprove the hypotheses that ●n
electrical hazard exists snd 8roundin8 will ●liminate or reduce thi~ hazard. The
first hypothesis (hazard ●xists) is ●ssesoed by ● comparison of ●aergy ●ource
levels with hazzrd threshold levels and sceaario particulars. The second hypothesis (8rounding reduces hazard) is ●ssessed by concideriag
the exteat
to which
●pplication of ●n ●lectrical grouad alters the svailable ●nergy. locstion of discharge, or duration of ha=ard. The results of the analyses ●re summarized in
paragraph 4.6.3 followiag the detailed ●aalysis below.
Electrical eaeruy
Action
Reflex
●ctioa shock
10 mJ, 50V
600mJ (at)
1.35 J (de)
Shock to personnel power
or 32 vac or 3 mA
or 45 vdc or 3 mA
Stores and equipment
EED ignition
Component damage
Component upset
35 mJ
35 mJ
10 mJ
Fuel vapor ignition
0.25mJ or 40 kV
261
MIL+IDBK-274(AS)
1 November 1983
4.6.1
The magnitude of potential
energy sources is compared with hazard thre-hold lwels to identify those
combinations which could result in a hazard.
4.6.1.1
An upper boundary of 0.03 mA defines
the vor~t case triboelectric
●nergy
source.
since in ●n ungrounded ●ircraft this current flows frcm ●arth. through the
aircraft tire resistances
to
the
●irfr~e, ●nd thence to the snows ducts ● tcc
nausing the effect, the pot~ti~l betueen ~irfr-e
A
earth
is determined
sheet
entirely by the tire resistance.
While laboratory ●easurements of tire resistance
in the 1OO-MQ Xan8e have been ~de, the vorst caae measured value of ~ ~~ ●
obtained in the field, i- used here tO c~pute ●irfrme potential of
V=IR=
Using
●
(0.03
*)(44)
m
) = 1200V.
value of C=O.005 pFD the ●nergy levels Us could reach
u=l/2cv2 =1/2(0.005pF)(1200V)2 =3.6 mJ.
Tbe Value of U ●nd V ●bove excted the hazard thre~~ld levels for fuel vapor
ignition ●nd nonlethal shock to personnel.
4.6.1.2
The value for the worst case Static
voltase
level
is 27 kV. In
addition, energy levels may range aa high aa 0.18 J. Capariaon with the hazard
threshold values in paragraph 4.5,5 shows that the thresholds
for reflex lwel
shock to personnel, fuel vapor
i~ition,
●nd stores
or
equipment
d-se
8re
exceeded.
4.6.1.3 During fuel tr~sfer
the •ep~ration
of charge caa result in ●lectrical
current of 13 @.
Also. measurements indicate that at the termination of a fueling
operation, ●fter bonding straps ● re disconnected, s c~pletely
isolated ●ircraft
may exhibit static voltage levels of ● s high ● s 2.5 kV. The 13-PA current flow due
to fuel transfer can result in voltages of
V=IR=
13 PA x 40 ?I!2=
520V
if only return path is through the ●irfr~e.
While this condition will not ●xist
when the aircraft is properly bonded to the fuel supply system. both improper
r..
‘-mnection of bond clips (to painted or no~etallic surfaces) and poorly maintained
‘bondingcables (100se
●rid/or
rltcted
connections)
were
obsemed during the field
~~wwey. Thus reliance on the bonding strap ●lone could, if the bond is faulty.
?~-~duce520V between airfr=e and earth or refueler. This represents an ●nergy
level, u, of
u=
l/2cv2
= l/2(0.005pF)(520V)2 = 0.68 do
4.6.1.4 In the case of ●lectrically
ieolated
the bond the available energy can reach
u=
l/2cv2
= l/2(0.005PF)(2.5
262
aircraft, ●fter disconnection of
kV)2 = 15.6 mJ.
)
MIL-HDBK-274(AS)
1 November 1983
4.6.1.5
These values ●xceed the threshold hazard values for ignition for fuel
vapor. Therefore. fuel vapor ignition
should
be considered
during
fuel
transfer.
For the electrically isolated aircraft. fuel vapor ignition, equipment upset. and
reflex shock reaction by personnel muut be considered.
4.6.1.6 The source level has been established as due to charge induced by storm
activity. Energy levels may then reach
u= 1/2CV2 = 1/2 (0.005PF)(60 kV)2 = 9 J.
l’heeelevels exceed threshold values for all hazards:
.
.
4.6.2 ~
Some of the phenomena cited in paragraph
4.6.1 are transient in nature. Knowledge of their duration is necessary to ●ssess
them as realistic hazards. Induced voltages, friction voltages, and voltage
buildups following fueling are considered transient.
4.6.2.1 Using the ungrounded aircraft resistance of 40 14S2. an aircraft
capacitance to ground of 0.005 IJF,and a safe voltage limit of lesn than 30Vt tbe
following time durations were computed from:
t
where t
R
= ()
RC in
‘i
Es
= time to reach Es after removal of source
= aircraft resistance to ground
c = aircraft capacitance to ground
Ei = initial (source) voltage
EB = safe voltage level
Time to E
Friction
After-fueling potential
Induced
27.0 kV
2.5 kV
60.0 kV
1.36 sec
0.88 oec
1.52 sec
4.6.2.2
Any traneient is objectionable from a safety standpoint. Ae stated
earlier- heart action discoordination (fibrillation) threhaold levels have time
durationa as low as 0.2 sec. Thus, the duration of even the shortest of the three
transience considered is unacceptably long.
4.6.3 ~
Ungrounded aircraft must be considered to be in jeopardy from
the indicated energy source, since at least one (and generally more than one)
hazard threshold level is exceeded during each ~cenario. These results are
263
—.—
MIL-HDBK-274(AS)
1 Novemb@r 1983
summarized in table 4-V below. The possibility of these hazardouo ●vents occurring
is ensured by the physical data available. However, ●ach is dependent
on ● number
(for ●xample. the
of factors which may occur simultaneously only very rarely
refueling of an ●ircraft with 40 ?fQ impedance
to ●arth, a fuel spillo snd ●n
electrical spark located at the right point in the volume of fuel vapor or misted
fuel to cause ignition). In any tingle one-time event. such aa ●n ●ircraft
repair
or refueling operation, consideration could be given to the fact that hazardous
o-ambimationsappear so seldom that they -Y
be WJlect~*
?louever~ when
consideration ie given to the number of navsl aircrsft involved- the rapid t~po of
operations, the fact that these are military operations (not ●lways conducted
under ideal conditions), tbe high cost of equipment. ●nd the threat to personnel
for safety
becomes ●n imperative requirement,
safety,
electrical
groundimg
Electrical airfrsme grounding. like safety belts in ●ut=obiles. ia ●tatimtically
indicated by, mong other thinge, the vast numbers involved.
)
4.6.4
In each of the scenarios considered the use of ●
proper ground connection ensures
that the airfrmie
is maintained ● t the same
potential ● s the ground point for those sources considered. ●xcept in the caoe of
external power systans. In ●ddition, since the airfrae resistance
to ground is
greatly reduced, the duration of such effects
as induced voltages is reduced to
fractions of a millisecond. Ae an additional ●dvantage, the use of ● proper
grounding procedure ensures that any ●rcing or electrical discharge ●$mociated with
the ●ct of connecting grounde take place at the ground point rather than near the
airfrume,
TABLE 4-V,
to
I
Scenario
Energy Source
Tribo
Friction
Fue1
trano
Atioapheric
induced
fielde
External
power
system
Lightning
t,
Maintenance
AD
ADE
Fue1
AD
ADE
Stores
Handling
AD
ACE
ACE
BCDE
Park
AD
ACDE
ACDE
BCDE
ADE
BD
BCDE
ACDE
BCDE
BCDE
1
where:
ACDE
A = Static shock to personnel
B= Power shock to personnel
c= Ordnance EED/stores miefire/releaee
D= Fuel vapor ignition
E = Electronic equipment damage
)
264
MIL-EDBK-274(AS)
1 November 1983
SECTION 5
OF ~
5.0
This
section
describes
techniques
necescary
for
sccurate
measuranent
of
resistance ground point~. Intended for uae by public works department personnel,
this section gives the theoretical background~ required measurement
●quipment. ●nd
measurement procedure. AIEO provided are a suggested schedule for testing. the
identification of ground pointe.~and the use of mooring eyeE aa otatic
ground
points.
For ●xplanation of the three terminal fall of
5.1
potential method, eee circuit shown in figure S-1. With a 30V source and a
measurement current of 6 amps, the resistance
of the resistor
is 5 ohms- aa
calculated by Ohm’s law.
5.1.1 In measuring ground points. measur~ent is taken of the resistance
between
the driven ground rod and the main body of earth. If a test connection could be
made on the centerline of the earth (se@ figure 5-2). Ohm’s law could again be
applied to the circuit. Since ouch a connection is impractical. an alternate
method must be used.
5.1.2 Picture a ground rod being surrounded by shells of earth. all of equal
thickness (see figure 5-3). The earth shell closest to the rod has the greateat
resistance
due to the fact that it has the smallest surface area. Each aucceasive
shell has a larger area than the prwioue one ●nd thus leas resistance. Farther
out, a point is reached where the inclusion of additional ●arth shells has no
●
significant effect on the resistance of the earth surrounding the rod. Therefore
measurement can be made (within a reasonable distance) between the ground rod and a
test rod.
5.1.3 In reality, the rod has a resistance (Rc) aB60ciated with it- TO exclude
reai6tance from the measurement, a three terminal test technique is used, as
shown in figure 5-4. The use of ● potential probe enablea a voltage measurement to
be made across R. Using the ammeter reading for the current through R, we can
compute the value of R using Ohm’O law. The reaiEtance of Rp iE very high, a
characteristic of all voltmeter probes.
this
5.2
Below iE a list of the preferred measurement
equipment manufactured by Jame6 G. Biddle Inotrumento. Similar testers by other
manufacturers that have equivalent characteristics may ●lso be used. Other meters,
such as VOW and VTVMa~ are not suited for the taak of providing accurate
resistance rnea6urementrn
of ground points. and therefore ohould not be used.
a.
b.
1 - Null balance earth tester. Biddle model no. 63241; with accessories
case, model no. 63850; accesaory kits model no. 63578; spare Ieade,
model no. 63576.
1 - Megger. Biddle model no. 21159: with accessories
case, model no.
217719; two 6et6 leads, model no. 21963B.
265
———_.
WL-HDBK-27f+(AS)
1 November 19B3
)
.
R
E=30v
.
.
1-6A
5031.3
FIGURE 5-1. _
266
?IIL-HD~-274(~ )
I November 1983
E=30V
50314
FIGURE 5-20
267
?IIL-IiDBK-274(fi)
1 November 1983
H
GROUND
ROD
5031-5
FIGURE 5-3.
I
.“
,. ,,.
,.
..
. . .
. .
..
“?.
,..
,.
i
ROD C
;..
.. . ... .. .
..”. ,
,. .,....
,*”.“
:“. .
,.
.“:,
., . . ,.,.
..
. ..
%~:.~””:,?.,:
,,.
,..:
....
./,
...,
.
.
.. .,,
,.
~
i.,.,. .
”,,
. “.,!.
. . .. . .:,.
.,..
,
50316
FIGURE 5-4.
I
268
MIL-EDBK-274(AS)
1 November 1983
The null balance
earth tester includes batteries for its voltage sourc?
5.2.1
The tester generatte ● n ● c
●nd an ohmmeter to measure the resistance directly.
test current which i8 paaeed between the ground rod ●nd the current
rod.
AC ia
used to eliminate errorrndue to existing dc currents and voltages that may be
present in the ●arth.
The voltage
drop ● t the potential rod in ●pplied to ● bridge
circuit and nulled with a three-decade variable resistance. When ●t balance (UO
current flouing through the potential rod), the ground resistance is obtained froa
Although other equivalent m~ters way
the readout of the digital decade witchee.
hsve different types of power supplies (euch an hand-cranked generators) ●nd
different readout devices, the principles of operation ● re still the same.
The following paragraphs provide
5 ●3
step-by-step procedures for performing accurate ground point resistance measurements ● The three-terminal fall of potential method should be used when measuring
ground points
on the apron.
This includeo
certified
power grounds.
certified
static grounds, mooring eyes- and FLEDS lightning
protection
grounds~
The tvotenninal
method ohould be used when measuring hangar ground points, the facility’s
ac neutral lines and in situations where the three-terminal method is impractical.
A resistance value of lees than 10 ohms is recommended for certifi~d power grounds~
FLEDS lightning protection grounds. hangar ground points. ●nd the facility’s ● c
neutral line. Certified static grounds and mooring ●yes ● rt recommended to be less
than 10,000 ohms.
.
5.3.1 ~of~
TM test setup for perfoming
the three-terminal fall of potential method ia shown in figur?
S-5.
This test is
performed as follws:
a.
b.
co
d.
Connect test lead 1 from the teeter to the ground point being
●valuated,
Drive a metal reference rod (rod C) into the ground at a distance of
100 ft (30.5 m) from che ground point being evaluated. Connect t~st
lead C from the tester to this rod.
Drive a metal rod (rod P) into the ground ●pproximately 62 ft (18.9 m)
from the ground point being ●valuated and in line with the reference
rod (rod C) installed in step b above. Connect teat lead P from the
tester to this rod (rod P),
Adjuot the resistance dials on the tester
until the indicator dial ia
center-d (zeroed) on the scale. When the dial ia centered, the
resistance value (in ohme) of the ground point being ●valuated
cam be
read directly on the tester’s digital readout.
.
The test setup for perfoming the
two-terminal method is shown in figure 5-6. ‘I’his teBt io performed as follwt:
5.3.2
~
a,
b.
Connect a jumper ecrooe the P and C teminals of the tester.
Connect teat lead I from the tester to the ground point being
evaluated.
269
MIL-EDBK-274(AS)
1 Novembm 1983
000
c
ROD
..
.,
...
...
...
.,,I.
—
,,,
P
.
ROD
C
L
1::,:
!., . ..”
1. . .
.,. :
!,.
~~~
J
~
lOOFT (30.5m) —
5031.1
FIGURE 5-5.
270
MIL-HDBK-274(AS)
1 Novemb?r 1983
F
000’
1%
GROUNDJNG
..
. .
WATER PIPE SYSTEM
(METALLIC) OR
EXTENSIVE
GROUNO SYSTEM
POINT
. ..O
. . . . . ... . . . . ! . .. .... ..... . .. . .“. : .. :’.” .-”
‘“, . .:,
.,
...
.
A
. ... .. . . ... .. .. . . . .,
. ., . ....’.. .... . ..
(“
, .”.”..-..
.. . ... .. . .
. . .
.. . .
L
L
“FT’30”’m)-
!$031.2
FIGURE 5-6. ~
271
HIL-HDBK-274(AS)
1 November 1983
c.
d.
5.4
reoiatance
Iacate a large. unpeint~d, metal water pipe at least
100 ft (30.5 m)
from the ground point being ●valuated and connect test lead C from
the tester
to this water pipe.
Adjust the resi~twice
dials on the tester
until
the
indicator dial is
centered (zeroed) on the scale. tien the dial is centered. the
resistance value (in ohms) of the ground point being ●valuated can be
read on the t?cter’s digital readout.
It it recommended
that
periodically
in
be p~rformed
order to determine if there hae been ●ny degradation of the grounding ●yatem.
It
is important to verify that the resistances of the ground points ● r~ ● t or below
so ● s to minimize
likelihood
of injury or damage. The
r~commended maximum values
recommended maximum reeiatance values
● re 10 ohms for
● power ground
point
●nd
10.000
ohms for a static ground point.
measurement
of
a facility~s
ground
points
between
reaimtance
ttatin8
ia 15 monthn,
This
The recommended time interval
that over ● 5-year period. the ground points will be tcoted during ●ll
Dep~ndiag
seasons, thereby providing a profile of stasonal resistance
variations,
on the number of ground points to be measured.
it might be more feasible
to employ
tim~ span.
a rotational
method,
rather
than measure
all of the points
in ● eingle
into five sectionao the measurement
task
For e~ple,
if the facility
were divided
would be initiated every three montho in a different section.
5.4.1
ensureo
5.4.2
The task
the public works
of measuring ground points
normally
comes under jurisdiction
of
department of the facility. Additionally. their responsibilities
will include setting up and carrying
out the teat schedule.
5.5
It is recommended that ground points
almeasured should be identified
in the mann~r indicated in figure 5-7.
Thin
identification indicates to personnel that the ground point is ●atimfactory.
ready
5.6
Mooring ●yes (also
referred to a- padeyeo) may be used ac static ground
pointo provided that they have
been measured ●nd identified
in ● proper manner (see paragraphs 5.3 ●nd 5.5).
‘hrveys (AIR-5181-1OOO) have indicated that samplings
of the r~ciotance
values of
mooring ●yes showed them to be under 10,000 ohms ●nd therefore
acceptable
● s static
ground points.
5-8 showrntypical mooring ●ye installation details.
Additional
●ailable
in NAVFACEIQGCOMTechnical Specification TS-02614. At some
facilities, a stainless steel bead has been welded to the upper exposed ● rea of the
aooring eye. This prevents
corrosion buildup on the mooring eye and reduces it~
likelihood
of providing a poor ground.
5.6.1 Figure
information
is
272
)
HIL-HDBK-274(AS)
1 November 1983
NOTES :
ALL LETTERS
1.
2,
TESTING
BE 1“ HIGH.
INFORMATION
AS SHOWN
22”
SHALL
WITH
3/4”
SHALL
SPACING
BE CENTERED
BETWEEN
LINES.
●
18”
r
GROUNDING
OHMIC TEST
BOX
TT-P-B5 REF LECTORIZED
YE LLOWIREFLECTORIZEO
’11
SEAOS, TT-B-1325ATYPE
[SEE SPECIFICATIONS)
—
TT-P-1 106 BLACK PAINT
GROUND
CONNECTION
5031.162
FIGURE 5-7.
273
MIL-HDBK-274(AS)
1 November 1983
\
)
4“ TO 5“”
b
4
?
2H
v
H
4
TROWELED
1,.,~
HEMISPHERICAL
T
DEPRESSION
*
.—-.
H
1%” MI N-
T
TYPE
“A”’
2’-0”
*
●
,8, ~~ ~..
1%” MIN.
~
?
?
1“’R
2H
H
HEMISPHERICAL
BAR @
3
*
t
DEPRESSION
.—
- —
H
w
1
3
*
@T
WE LD7JCIOF
BAR
&
TYPE
“’B”
TO 12”
BAR o
3}48’
,.
1
TO 16”’
1-1/4”
H
<10”
13”
1
9“
II
10”
I
u
&
4
NOTES.
1
PLACE
ENTIRE
MOORING
SURFACE
OTHERWISE
2
PLACE
EYES IN THE CENTER
OF WAR M-UPOR
OF EACH
PARKING
125’
AREA
BY 150’
PAVEMENTS
SLAB
OVER
UNLESS
INDICATED
MOORING
EYES
IN HANGAR
FLOORS
AS DETERMINED
BY PROJECT
REOUIREVENTS
5031.163
FIGURE 5-8,
~
274
MIL-IIDBK-274(AS)
1 November 1983
5.7 ~
conditions prevent
.
.
If
grounding or bonding points, ●
resistance
check must be p~rformed to verify that the alternate location io an
●cceptable grounding or bonding point.
It is r~commended that a Shallcrooo No.
670-A Millipheter or equivalent bc used.
the
use
of
known aircraft
5.7.1
Prior to perfo~ing r~aistance measurements. the meter must be calibrat~d.
Routine checks on the reliability of the readinga
ar~ obtain~d by using
t~at
●tandard rcsistora.
A test
standard
r~oistor
of 0.0025
ohms ia supplied with the
meter. The calibration reading should be accurat~ within 5 percent of full ocale.
Should the reading not be ●ccurat~, resistor values within
thr meter munt be
refer to the
changed.
For a detailed
procedure
of changing
internal
resistors.
Shallcroas Operating ●nd Maintenance Instruction Manual.
llf
The tent setup for performing resistance measurements is shown in figure
This test is performed as follows:
5.7.2
.
5-9.
Connect the clamp type probe to the known aircraft grounding point.
Connect the second probe to the proposed alt?rnate grounding or
bonding location. Make certain that the probels two tips are making
good contact with this location.
c. Place “OHM FULL SCALE” ael~ctor switch on highest range and change
the range setting
in descending
order until largest deflection i8
depreaBed.
Bwitch
is
Prior
to depressing
obtained when the !~~sTl?
“TEST”
switch.
make sure meter is properly adjueted to the red line
or full IBcalpposition as determined by the range selector.
a.
b.
275
—
.
HIL-EDBK-274(M)
1 Hov-bm
1983
)
&-\.:/’
\
/’
\\
.;
1989
705 060
276
2*S
/
RXL-HDBK-274(A8)
1 November 1983
Cumtodianz
y!~’yy - As
277
Preparing
Navy
(Project
Activity:
- AS
EMCS-?J105)
I
[NOT MEASUREMENT SENSITIVE I
MIL-HDBK-274(AS)
NOTICE 1
29 June 1990
MILITARY HANDBOOK
ELECT~W
GROUNDING
FOR AIRCRAFT SAFETY
TO ALL HOLDERS OF MIL-HDBK-274(AS):
1.
THE FOLLOWING PAGES OF MIL-HDBK-274(AS)
THE PAGES LISTED:
NEW PAGE
v
vi
i
3
4
;:
25
26
27
28
%
31
32
35
36
37
38
39
40
41
42
43
44
44a
71
72
73
;:
76
77
78
79
DATE
29 June 1990
1 November 1983
1 November 1983
29 June 1990
29 June 1990
29 June 1990
29 June 1990
1 November 1983
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
1 November 1983
29 June 1990
1 November 1983
1 November 1983
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
1 November 1983
29 June 1990
1 November 1983
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
AMSC N/A
1).ISTRIBUTJ.ON
STA1’tMENT A.
HAVE BEEN REVISED AND SUPERSEDE
SUPERSEDED PAGE
DATE
v
VI
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~
3
4
23
24
25
26
27
28
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1 November 1983
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AREA EMCS
ADDroved for Dublie release; ciis~ribution is unlimited.
MXL-HDBK-274(AS)
29 June 1990
NEW PAGE
80
131
132
137
138
149
150
150a
159
160
160a
161
162
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164
167
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238
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2.
DATE
29 June 1990
1 November 1983
29 June 1990
29 June 1990
1 November 1983
29 June 1990
1 November 1983
29 June 1990
1 November 1983
29 June 1990
29 June 1990
29 June 1990
29 June 1990
29 June 1990
1 November 1983
29 June 1990
29 June 1990
1 November 1983
29 June 1990
29 June 1990
29 June 1990
1 November 1983
29 June 1990
1 November 1983
29 June 1990
29 June 1990
29 June 1990
29 June 1990
1 November 1983
1 November 1983
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1 November 1983
29 June 1990
29 June 1990
DATE
SUPERSEDED PAGE
80
131
132
137
138
149
150
New Page
159
160
New Page
161
162
163
164
167
168
179
180
181
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184
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238
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263
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277
1 November 1983
1 November 1983
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1 November 1983
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RETAIN THIS NOTICE AND INSERT BEFORE TABLE OF CONTENTS.
3.
Holders of MIL-HDBK-274(AS) will verify that page changes and additions
indicated above have been entered. This notice page will be retained as a
check Bheet. This issuance, together with appended pages, is a separate
Each notice is to be retained by stocking points until the
publication.
military standard is completely revised or canceled.
Preparing Activity:
Navy - AS
(Project EMCS-N127)
MIL-HDBK-274(AS )
29 June 1990
CONTENTS
Page
Paragraph
SCOPE ........... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 .,......0
. **..*.,..
. . . . . . . . . . . . . . . . . . . . . . . . . .
Purpose . . . . ...0.0
Referenced Documents .................................
1
1
2
AIRCMPT GROUNDING AND BONDING ~THODS .................
Land-based aircraft ..................................
Carrier-based aircraft.. .............................
Helicopter hovering .. ................ ... . *..... .
External electrical power. .. .........................
Aircraft fueling when using external electrical
power (A-6) .. ,. . ..*,..........*...* ... ...c......
Hot fueling ......... ...... ....... *..0. .0.*. . *O**
4
4
149
205
209
OPEMTIONAL
GROUNDING CONCERNS . ....................*...* ,* .
Static electricity ....,... .....*...................,
::;
Energy sources.. .....................................
Operational procedures.. .............................
3.3
3.4
Special considerations ...............................
Actual grounding problems. ...........................
3.5
Measurement of static ground and electrical
3.6
power ground points ..................................
3.7
Grounding hardware/receptacle considerations .........
Groundihg hardware military specification sheet
3.8
reference list .......................................
222
222
223
231
235
238
4.0
4.1
4.2
4.3
4.4
4.5
4.6
THEORETICAL BASIS FOR AIRCIUFT GROWDING ...............
Electrostatic theory ........... ......................
Scenarios ............................................
. ..0
.*..
. . . .
Energy sources ..........,. ........ .
Airframe/personnel electrical parameters ............”
Damage threshold levels.. ............................
Analysis .... .....,. .*....... ... ....0 .............
242
242
242
242
257
260
261
5.0
5.1
5.2
5.3
5.4
5.5
5.6
5*7
TESTING AND IDENTIFICATION OF GROUND POINTS ............
Theoretical background ...............................
Measurement equipment ................O .........O.O.. .
Ground points measurement procedures .................
Schedule for resistance testing of ground points .....
Identification of ground points ......................
The use of mooring eyes as static ground points ......
Resistance measurements for alternate
grounding and bonding points. ..... ...................
265
265
265
269
272
272
272
INFORMATION FOR GUIDANCE ONLY ...... .0. . ..* . . . . . . . . . . . .
Changes from previous issue .........................
Subject term (keyword) listing ......................
277
277
277
1.0
1.1
1.2
2.0
2.1
2.2
2.3
2.4
2.5
●
●
2.6
3.0
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
●
6.0
6.1
6.2
●
●
●
Supersedes page v of 1 November 1983
v
●
●
●
●
●
●
●
217
220
240
240
241
273
—.
—.
—.——
MIL-HDBK-274(AS)
1 November 1983
FTGURES
Figure
2-1
2-2
2-3
2-4
2-5
2-6
2-7
2-8
2-9
2-1o
2-11
~-1~
2-13
2-14
A-3 aircraft grounding, parked evolution ................
A-3 aircraft grounding, fueling/defueling evolution .....
evolution ...............................................
evolution ...............................................
A-4 aircraft grounding, parked evolution .....t........ ..
A-4 aircraft grounding, fueling/defueling evolution .....
evolution ...............................................
evolution ...............................................
A-4 aircraft grounding, stores loading/unloading
evolution ...............................................
A-6 aircraft grounding, fuelingldefueling evolution .....
evolution ...............................................
evolution ...............................................
A-6 aircraft grounding, scores loadingfunloading
evolution ........................................... ...
A-? aircraft grounding, fuelingldefueling evolution .....
evolution ..........................................”.. ..
evolution. ..............................................
A-7 aircraft grounding, stores loadinglunloadin~
evolution. ..................................... ........
AH-1 aircraft grounding, parked evolution ...............
AH-1 aircraft grounding, fueling/defueling evolution.”*Hangar-based AH-1 aircraft grounding, maintenance
evolution ...............................................
Apron-based AH-1 aircraft grounding, maintenance
evolution ...............................................
AH-1 aircraft grounding, stores Ioadinglunloading
evolution ...............................................
AV-8 aircraft grounding, parked evolution ...............
AV-8 aircraft grounding, fuelingldefueling evolution ....
Hangar-based AV-8 aircraft grounding, maintenance
evolution. ......... ......................**....”..”.....
Apron-based AV-8 aircraft grounding, maintenance
evolution ..................................... ..........
AV-8 aircraft grounding, stores loading/unloading
evolution ....................................”.”0.””..s.
●
2-15
2-16
2-17
2-18
2-19
●
2-20
2-21
2-22
2-23
2-24
2-25
2-26
2-27
2-28
2-29
vi.
6
7
8
10
11
13
14
15
17
18
19
21
~~
24
25
26
27
29
31
32
33
34
36
37
39
39
41
42
44
MLL-HDIIK-274(A5)
1 November 1983
SECTI02i 1
1,0
SCOPE
The purpose of this handbook is to provide aircraft maintenance
1.1 Purpose.
personnel with the information required for electrical safety grounding of each
type of operational aircraft in the U.S. Navy inventory.*
in addition, this
handbook provides background information pertaining to the operational concerns
for aircraft grounding, static electricity theory and how it affects aircraft,
and techniques used for measurement of grounding points.
This handbook is
divided into five sections as follows:
SECTION
SECTION
SECTION
SECTION
SECTTON
1
2
3
4
5
-
SCOPE
AIRCRAFT GROUNDING AND BWWING METHODS
OPERATIONAL GROUNDING CONCERNS
TESTING AND IDENTIFICATION OF GROUND POINTS
1.1,1 This handbook is intended for use by all U.S. Kaval aircraft
operational
and maintenance personnel including maintenance officers and public works
officials for the purposes of ensuring that each aircraft is properly grounded
and that the grounding system is adequate for this purpose.
Sections 1 and 2
are intended primarily for use by line maintenance personnel.
Sections 3 and f+
contain material intended for those desiring to obtain additional theoretical
and background information.
Section 5 is essential for public works department
personnel.
Each section is designed to stand alone.
1,1.2 The information contained in Section 2 is intended to be used by line
maintenance personnel.
This section provides step-by-step instructions for
grounding each of the aircraft in the Navy inventory during each of the
parked, fueling/defueling, maintenance, and stores loading/
following evolutions:
unloading.
Each evolution is shown in a separate illustration depicting the
The
particular aircraft with proper groundingjbonding cables connected.
illustrations show primary grounding points and also provide alternate grounding
points should the primary grounding point be inaccessible.
AISCI provided on the
illustrations are pertinent cautions and warnings to be observed during the
grounding procedure.
Accompanying each illustration is a step-by-step procedure
for grounding/bonding the particular aircraft.
1.1.3 Section 3 provides background and general information necessary to
understand the rationale behind the requirements for grounding and bonding. This
section also discusses the grounding problems and hazards encountered in the
Energy sources and
everyday ground handling of aircraft during flight operations.
grounding effects are identified. The aircraft scenarios or servicing situations
(evolutions) are introduced and the aircraft safety problems associated with each
In addition, a brief discussion of static electricity and how it
are described.
affects aircraft operation is provided.
ifu.s. Navy
(GF1).
aircraft use power
equipment
not
equipped
with
ground
fault inLf2rKUptf2rS
FK1.L-HDBK-274(AS
)
29 June 1990
1.1.4 Section 4 details basic electrostatic theory and Its application to
aircraft grounding. Sources of static electricity associated with aircraft
operation are also described. These include triboelectric effects, fuel flow,
fnduced charge, and frlcti.on. Hazards from ground power faults, rf energy,
and lightning are presented. Also included in this section are descriptions
of aircraft electrical parameters and a discussion of hazardous threshold and
the possible dangers they present to personnel and aircraft safety. The
section also illustrates that proper grounding will reduce these hazards.
1.1.5 Section 5 is intended for use by the public works department
personnel and provides a description of the methods and techniques used to
measure the resistance of the grounding system. Also included in Section V is
a suggested schedule for accomplishing the measurement of ground points,
Identifying ground polntg, the use of moortng eyes as etatic ground points,
and a discussion of the test equipment used to measure ground point resistance.
1.2 Referenced Documents.
handbook.
The following documents are referenced in this
Document No.
Title
NIL-c-83413
MIL-c-83413/l
Connectors and Assemblies, tilectrical, Alrcrart
Type I Grounding Assembly, Discharger,
Grounding:
Electrostatic
MIL-C-83413/3
Connectors and Assemblies, Electrical, Aircraft
Grounding:
Type 111 Grounding Assembly, Discharger,
Electrostatic
MIL-c-83413/7
Connectors and Assemblies, Electrical, Aircraft
Grounding:
Grounding Clamp Connector for Types I and
III Grounding Assemblies Clip, Electrical
MS3493
Connector, Plug and Cap Electric, Grounding
MS25083
Jumper Assembly, Electric Bonding and Current Return
MS25486
Connector, Plug, Attachable, External Electric Power,
Aircraft, 115/200 volt 400 hertz
MS25487
Aircraft, 28 Volt DC, Jet Starting
)1S25488
Aircraft, 28 Volt DC Operating Power
MS33645
Receptacle, Grounding, installation
MS90298
Connector, Receptacle,
NIL--HDBK.J+29
-’S!lic:dl.
r.g fur Electzor.ic
‘Croundi~g, I?oadi;lgjan{.
Equipments and Facilities, 21 .January 1982
2
of
Electric, Grounding
MIL-HDBK-274(AS)
29 June 1990
Document No.
Title
NAVAIR AIR-5181-100() Airframe Electrical Grounding Requirements
Final Report, 17 Feb 1981
Program
NAVAIR 00-80T-96
U.S. Navy Support Equipment, Basic Handling and Safety
Manual, 1 April 1981
NAVAIR 19-45-1
Index and Applications Tables for Mobile Electric
Power Plants, 1 September 1972
NAVSEA 0P4 Vol. 2
Ammunition Afloat, 15 February 1972
NAVSFA OP5 Vol. 1
Ammunition and Explosives Ashore, 15 October 1974
COMNAVAIRPAC/
CONNAVA.IRLANTINST
3100 .4A
Air Department Standard Operating Procedures
(SOP)
MIL-HDBK-274(AS)
29 June 1990
SECTION 2
2.0
AIRCRAFT GROUNDING AND BONDING METHODS
This section provides step-by-step procedures for grounding and bonding
operational aircraft in the Navy inventory. Various handling evolutions, both
landbased and carrier-based, of the different aircraft are described and
illustrated with appropriate warnings and cautious.
Note that the word
“carrier” is meant to refer to any ship which supports aircraft flight
operations.
in this section and the
By referrf.ng to the partic~ar
aircraft procedures
applicable aircraft NATOPS, organizational maintenance personnel will be able
to properly determine aircraft grounding requlr~ents
before beginning other
seticing.
Recommended grounding and bonding locations are illustrated. If
conditions prevent the use of these locations , a resistance check using a
mllllohmmeter must be performed to verify that the alternate location IS an
acceptable grounding or bonding attachment point. A location is an acceptable
grounding or bonding point if the resistance measured from the point to the
airframe is less than 10 milllohms.
Using a milliohmmeter (Shallcross Model
670A or equivalent), connect one probe to the known aircraft grounding point
and the other probe to the proposed grounding point. Observe the milliohmmeter for a reading of less than 10 milliohma.
If the milliohmmeter
reading IS less than 10 milliohms, the proposed grounding point is acceptable. Painted, corroded, dirty, greasy areas or areas of composite materials
should not be used for grounding points. In addition, if the intended
grounding point is loosely connected LO the aircraft structure by way Of
bearings or springs, an unacceptable intermittent ground or bond could result.
nen employing grounding cables, the specific type of connector required on
the ends will be determined by the aircraft type. Many Navy aircraft do not
have grounding receptacles available in other than the fueling area, and they
are therefore not readily avaflable for use as the static grounding point On
the aircraft.
In these instances a cable havfng an M83413-1 connector on each
end may be used, one end attached to an approved static ground point, the
other to a clean metal area of the aircraft.
Cables shall be of 7 x 7 construction, 0.094 inch nominal diameter wire rope
in accordance with M83413-1 or with MIL-c-83413/7 clamps at each end. Cable
length shall be determined by user requirements but shall not exceed 40 feet.
The maximum resistance of all cable configurations shall not exceed 10 ohms.
The cables must be identified and serialized. As a minimum, resistance of
complete cable assemblies must be measured, recorded and verified annually.
2.1 Land-Based Aircraft.
The following paragraphs provide step_by_6tep
procedures for grounding land-based aircraft.
Evolutions
2.6.
requiring external power are detailed in paragraphs 2.4 through
Fueling evolutions shown here do not indicate external electrical power.
These illustrations apply to gravity fueling as well as hot fueling from fuel
trucks. F@JTes
2- ~60 .~ad 2-161 j,~l,~~tr~tegroundj.ng and bonding p~cIcedu?es
for the A-6 using external electrical power during fueling. The grounding and
bonding procedures for other aircraft requiring external electrical power
during fueling are similar.
Supersedes page 4 of 1 November
1983
4
MIL-I{DBK-274(AS)
29 June 1990
2.1.17 A-6 stores loading/unloading evolution.
To ground A-6 aircraft
a.
b.
c.
location Is not accessible, then connect grounding cable to main
To remove grounding cable, reveree above procedures.
2.1.18 A-7 parked evolution.
To ground A-7 aircraft when in the parked
8.
b.
c.
d.
(clamp type) to a certified static ground ur padeye (1).
Connect free end of grounding cable to grounding receptacle in
left-hand wheelwell (2).
If grounding receptacles are not accessible, then using a
grounding cable with M83413-1 electrical ground connector at
each end, follow step a, and connect free end of grounding cabie
to nose gear tiedown ring (typical alternate grounding point).
10 grouud A-7 airc~af~
2.1.19 A-7 fueling!defueling evolution.
fueling or defueling, proceed as follows (see figure 2-16):
a.
b.
c.
d.
;:
8.
~Ii~~
each end, follow step a, and connect free end of grounding cable
If using fuel truck, attach its grounding cable to a certiffed
static ground or padeye (3).
When fueling/defueling evolution has been completed, wait a
minimum of 2 min before removing bonding cable.
To remove bonding or grounding cable, reverse above procedures.
2.1.20 A-7 hangar-based maintenance evolution.
TO ground A-7 aircraft
during maintenance in the hangar, proceed as follows (see figure 2-17):
ir
t:, (:ncnect f’~peml!, of ~rt:urld:o~catl.c to [zrnund~nq receptacle
a.
/
.,
TAIL LIUMPEIT
GROUNDING POINT
TYPICAI
AL TER~A_TE
GRouNDING
POINT USING
CON?4ECTOR \
> \
(%
‘
/
\
wAfT?41NG
TIE (TOWN CNA!NS CAN NoT
BE USED TO GROUNO AI TTCITAF1
SEPAn ATE GROUNOING CAflLf
MUST 8[ USELT
\
.-----$----- +,,,,,
CoNNLCTol+
k1\,,
%
.,---,? ;;’,
.(:
‘-
\
\
M83413I
~,
y
\
‘%_)
CAUTION
TIE DOWN RING
hWST
/
/’
zr
01
<z
mu
3m
a-z
ml
-lrw
\-T——==——
L
GROUNDIN( 3CA13LE ccl FJtwECTTO
TAl
. . ..L BUMPER
o\
2
4
(D&
r
1
~.
Q)
CAUTION
EAf7TM GRO(JNO POltJT
MuST IIE fnEE OF
pAINT ANEI COllllOSION
3
l)
~
““ 1
-1=
CERTIFIED GROLJNO
OR
PAOEYE
I LESS THAN 10.0000HMsI
FIGURE 2-14.
A-6 aircraft grounding, stores loading/unloading evolution.
Ml1.-H1)Iw-274(AS
)
29 June 199(I
Supersedes page 25 of 1 November 1983
25
.
1
m
lx
—.
.
—
.—. —
MIL-HI)BK-274(AS)
29 June 1990
c.
d.
2.1.21 A-7 apron-based maintenance evolution (with MEPP plugged Into
aircraft).
To ground A-7 aircraft when In the maintenance evolution on the
apron with MEPP plugged into aircraft, proceed as follows (see figure 2-18):
a.
Attach grounding cable with M8341.3-I electrical ground connector
NOTE : If the MEPP is an electrically-driven
ground must be used.
b.
c.
d.
e.
f.
type, then a power
to nose gear tiedom ring (typical alternate grounding point).
Connect free end of bonding cable to a bare metal area on the
MEPP (4).
2.1.22 A-7 apron-based maintenance evolution (using FLEDS). To ground A-7
aircraft when in the maintenance evolution on the apron using FLEDS, proceed
a.
b.
c.
d,
e.
f.
Connect free end of bonding cable to a bare metal area on ~he
DBA such as the stud or bolt (4) (see figure 2-155).
cable, reverse above procedures.
To remove grounding or bonding
Supersedes page 28
Oi
1
November 19G~
28
Supersedes
page
29
of
1
1983
lil
L-liDB}:-274(AS
)
~g June 1990
November
.29
.
—
MIL-HDBK-274(AS)
29 June 1990
2.1.23 A-7 stores loading/unloading evolution. To ground A-7 aircraft
a.
b.
c.
d.
Connect free end of grounding cable to grounding receptacle In
each end, follow step a, and couect free end of grounding cable
2.1.24 AH-1 parked evolution. To ground AH-1 aircraft when in the parked
a.
b.
c.
Connect free end of grounding cable to front right towing ring
(~). If this location IS not accessible, then connect grounding
cable to front left towing ring (typical alternate grounding
point).
TO ground AH-1 aircraft when
2.1.25 AH-1 fuelinR/defueling evolution.
fueling or defuellng, proceed as follows (see figure 2-21):
a.
b,
c.
d.
e.
f.
point).
If using fuel truck, attach its grounding cable to a certified
Connect fuel truck bonding cable to front right towing ring (4).
2.1.26 AH-1 hangar-based maintenance” evolution.
To ground A.H-l aircraft
during maintenance evolution in the hangar, proceed as follows (see figure
2-22) :
a.
b,
c.
cable to front right towing ring
point).
MIL-HDBK-274(AS)
29 June 1990
:j
1
4
.
m
WARNING
TIE OOWN CNAIN5 CAN NOT
S1 PAn ATE GIIOUNDING CAnl F
MUST BE USEO
w
N
-2
.G -
m>
,—.
w rn
CAUTION
EAnTH GnOUNO POINT
MuST llE FnEE OF
PAINT ANO COn ROSION
o1 =
GROUNDING CABLE CONNECT TO TOWING RING
/
CERTIFIED GROUND
OR
PAOIYE
(LESS THAN 10,000 0Hh15)
FIGURE 2-20.
AH-1 aircraft grounding, parked evolution.
MIL-HDBK-274(AS)
29 June 1990
2.1.27 AH-1 apron-based maintenance evolution (with MEPP plugged into
aircraft).
To ground AH-1 aircraft when in the maintenance evolution on the
a.
b.
point).
NOTE : If the MEPP is a diesel engine-driven
following bonding requirement is waived.
c.
d.
e.
type, then a power
type, then the
to front right towing ring (3)=
Connect free end of bonding cable CO a bare metal area on the
MEPP (4).
To ground AH-1 aircraft
2.1.28 AN-1 stores loading/unloading evolution.
a.
b.
c.
cable to front left towing ring (typical alternate 8rounding
point).
To ground AV-8 aircraft when in the parked
2.1.29 AV-8 parked evolution.
a.
b.
c.
Connect free end of grounding cable to outrigger gear tledown
ring (2). If this location is not accessible, then connect
grounding cable to bottom part of outrigger gear leg (typical
alternate grounding point) or to grounding point under main wing
tips (2a) (as applicable) or grounding point on forward fuselage
(2b) (as applicable).
2.1.30 AV-8 fuellngldefueltng evolution.
To ground AV-8 aircraft when
fueling or defueling, proceed as follows {see figure 2-26):
a.
Attach grounding
LO
(Claffiptj’~~>
d ie~tliied ~t~~l~ &~OUliLl
i)i
pdd~~~
{1).
1983
35
WARNING
TIE DOWr4 CHAINS CAN NOT
8E USED TO GROUNO AIRCRAFT,
SEPARATE GROUNDING CABE.E
MUST BE USED
CAUTION
T(2W RING
MuST8E FREE
OF PAINT
&ND CORROSION \
.
BONOING CABLE CONNECT TO TOW RING
*&?
ML33413.1
CONNECTOR
< \
\@
TYPICAL
\ AL TEn NATE
GRCUNOINGPOINT
USING CONNECTOR
7
\
o
3
fnn!v-
u
Y
GROUNOINGC&lll
E_
~::%%;:::;,
TOWING RING
=~
PowIR
RECEPTACLE ON LEFT SIDE
OF FUSELAGE
\\
CERTIFIED GROUND
(LESS THAN 10.000 OHMS)
CAUTION
EARTH GROUND POINT
MUST BE FREE OF
pAINT AND CO fEROSION
NOTE
THE80NDINGOF
THE
:SSIIOWN 0NL% FOn
ILLuSTRATIVE
PUnPOSIS
IT IS REOUlf7E0 ONLY
W}4EN THE MENI IS
AN :LECTF41CALLY DRIVEN
TYPE
FIGURE 2-23.
KY’
NC–8A
Apron-based AH-1 aircraft groundin g, maintenance evolution.
WARNING
TIE O(YWN CHAINS CAN NOT
BE USED TO GnOUMO AIRCRAFT.
SEPAnATE GROUNDING CABLE
MH9E
USED
[
TOWING RING
MUST BE FnEE OF
PAINT AND CORROSION
1
\’N7+s
CAUTION
EARTH GROUND I’OINT
MuST BE FREE OF
PAINT AND CORROSION
o
1
GROUNOING CABLE CONNECT TO TOWING nlNG
-&
=
CEn TIFIEO G170UN0
on
PADEYE
(LESSTHAN 10.COOOHMS)
FIGURE 2-24.
AH- I aircraft grounding, stores Ioadinglunloading evolution.
—.
MIL-HDBK. -274(AS)
29 Ju:Ie 199CI
. .. .
.
mLL-HDBK-274(AS )
29 June 1990
39
a
~
MIL-HDBK-274(As)
29 June 1990
b.
c.
d.
e.
f.
Connect free end of grounding cable to outrigger gear tiedown
tips (2a) (as applicable) or groundi~
point on O forward
fuselage (2b) (as applicable).
2.1.31 AV-8 han”gar-based maintenance evolution.
‘lo ground AV-8 aircraft
2-27) :
a.
b,
c.
grounding cable to bottom part Of outrigger gear leg (typical
alternate grounding point) or to grounding point under ❑ain wing
2.1.32 AV-8 apron-based maintenance evolution (with MEPP plugged into
aircraft). To ground Av-8 aircraft when In the maintenance evolution on the
a.
ground ❑ust be used.
b.
c.
d.
e.
type, then a power
Connect free end of grounding cable to outrigger gear tledown
to main wheel axle (3).
Connect free end of bonding cable to a bare ❑etal area on the
MEPP (4)*
To remove grounding or bonding cable, reverse the above
procedures.
2.1.33 AV-8 apron–based maintenance evolution (using FLEDS). To ground
AV-8 aircraft when in the maintenance evolution on the apron using FLEDS,
proceed
as follows
(see figure
2-28):
40
o
a
MIL-HDBK-274(AS)
29 June 1990
Supe~sedes page 41 of 1.November 1.983
41
L
A
F[lL-HDBK-274(AS)
29 JuIle 199(J
,,
.. .!
MIL-HDBK-274(AS )
29 June 1990
a.
b.
c.
d.
e.
DBA such as the stud or bolt (4) (see figure 2-3.55).
2.1.34 AV-8 store6 losding/unloading evolution.
a.
b.
c.
cable
to outrigger gear tiedown
tips (2a) (as applicable) ox grounding point on forward fuselage
2.1.33 C-1 parked evolution.
a.
b.
c.
Connect free end of grounding cable to nose gear towing ring
cable to main gear tiedown ring (typical alternate grounding
point).
2.1.36 C-1 Fueling/defueling evolution.
To ground C-1 aircraft when
a.
b.
c.
d.
e.
f.
Connect free end of ground cable to nose gear towing ring (2).
If this Iocatlon is not accessible, then connect grounding cable
to main gear tiedon ring (typical alternate grounding point).
Connect fuel truck bonding cable to nose gear towing ring (4).
1983
43
o
H1
P
‘Q
m
C.J
w
\
Y
n
~o
$4M.I
.. .—
rAut
20 UNDER BOTH
wING TIPS
. .
/
CONNECTO17-
‘\
STE[L 717 WIRE
YE
(LESS THAN 10.CCUOHMSI
CAUTION
EARTMGROUP40POINT
MuST BE FflEE OF
PAINT AND COfS170S10N
B
-.
71: r
+-u
cONNECTOR
\’,
..,1
.8
I
,. ..:,,
,,
ALTERNATE GROUNOING
APPROVtO STATIC2
(TYPICAL)
GROUND
FIGURE 2-29.
AV-8 aircraft grounding, stores loadinglunloading evolution.
\
MIL-HDBK-274(AS)
29 June 1990
2.1.37 C-1 hangar-based maintenance evolution.
To ground C-1 aircraft
2-32) :
a.
b.
c.
Attach grounding cable with N83413-1 electrical ground connector
Connect free end of grounding cable to nose gear towing ring
cable to main gear tiedown ring (typical alternate grounding
point).
44a
.
‘I
GROIJNDING
POINT
WARNING
llE USED TO GROUNO AlnCRAF7.
MUST I?E USED
e
c’\
-J
EART
,MiJ
PAINT
. .
C[n TIFIEDGROUiD
(LESS THAN 10.000 OHMS)
ET
L
CAOLE
E>:TERNAL POWER
receptacle
FIGURE 2-50.
Apron-based EA-6 aircraft grounding,
maintenance
evolution.
MIL-HDBK-274(AS)
29 June 1990
c.
d.
e.
Attach bonding cable with M83413-I electrical ground connecror
to bracket inside nose wheel well (3).
MEPP (4).
2.1.59 EA-6 apron-based maintenance evolution (using FLEDS). TO ground
EA-6 aircraft when in the maintenance evolution on the apron using FLEDS,
a.
b.
C.
d.
e.
location is not accessible, then connect grounding cable to
bracket inside nose wheel well (typical alternate grounding
point).
to bracket inside nose wheel well (3).
D5A such as the stud or bolt (4) (see figure 2-155).
To remove grounding Or bonding cable, reverse above procedures.
2.1.60 EA-6 stores loading/unloading evolution.
To ground EA-6 aircraft
a.
b.
c.
(clamp type) to a certified static ground or padeye (1),
location is not accessible, then connect grounding cable to
bracket inside nose wheel well (typical alternate grounding
point).
To remove grounding cable, reverse
above procedures.
2.1.61 F-4 parked evolution.
TO ground F-4 aircraft when in the parked
a.
b.
c.
d.
Connect free end of grounding cable to engine nacelle grounding
receptacle (typical) (2) or to grounding receptacles on main
wings (2a) (as applicable).
to main gear tiedown ring (typical alternate grounding point).
To ground F-4 aircraft wklen
2.1.62 F-4 fueling/defueling evolution.
fue]ing Or defueling, proceed as follows (see figure 2-53):
a.
TYPICAL
ALTERNATE GROUNDIIJG
.:/-:–
(g’
WAnNING
TIE 00WN CNAINS CAN !{01
BE USED TO GnOUNO Alnr-n AFT,
SEPARATE GnOUNOING !’ABLE
MUST flE USED
J
—-’
M83413.1
CONNECTOR
.
TAIL BUMPER
GROUNDING POINT
.J
.,.,
0.!2.
1
=
CERTIFIEO GROUNO
OR
PAIIEYE
ILESS TNAN 10.0000HMS)
FIGURE 2-51.
CAUTION
EARTH GROUNO FOINT
MUST BE FREE OF
PAINT ANO CORROSION
EA-6 aircraft grounding, stores Ioadinglunloadi?g evolution.
+’u
u
}LIL-HDBK-274(AS)
29 Jur.e 1’3?C’
74
3
u
c
o
-t+
4
aI
0
>
MIL-HI)BK-274(As)
29 June 1990
75
.
In
m
I
ml
k
u
MIL-HDBK-274(AS)
29 June 1990
b.
c.
d.
e.
f.
g.
2.1.63
during
Connect fuel truck bonding cable to main gear tiedown ring (4).
wait a
When fueling/defueling evolution has been completed,
To groud F-4 aircraft
F-4 hanger-based maintenance evolution.
in the hangar,
proceed
maintenance
a.
b.
c.
d.
Connect free end of groundtng cable to engine nacelle grounding
grou~d connector UL
grouuding cable wicli 1183413-1 electrical
above procedures.
To remove grounding cable, reverse
2.1.64 F-4 apron-based ❑aintenance evolution (with MEPP plugged into
aircraft). To ground F-4 aircraft when i.nthe maintenance evolution on the
a.
ground must
be used.
b.
c.
d.
e.
f.
type,
then
a
Power
to main gear tiedowm ring (3).
MEPP (4).
MIL-liDBK-274(As)
29 June 1990
~,
u-l
I
.
u
m
MIL-I{L)BK-274(AS)
29 June 1990
/’
u)
I
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u-l
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u
b.1
MIL-HDBK-274(AS )
29 June 1990
2.1.65 F–4 apron-based maintenance evolution (using FLEDS). To ground F-4
aircraft when in the maintenance evolution on the apron using FLEDS, proceed
a.
b.
c.
d.
e.
f.
to main gear tiedcnrn ring (3).
DBA such as the stud or bolt (4) (see figure 2-155).
TO remove grounding or bonding cable, reverse above procedures.
2.1.66 F-4 Btores loading/unloading evolution. To ground F-4 aircraft
a.
b.
c.
d.
(clamp type) to a certified etatic ground or padeye (1).
receptacle (typfcal) (2) or to grounding receptacles on main
2.1.67 F-14 parked evolutton.
To ground F-14 aircraft when In the parked
a,
b.
c.
Attach grounding cable with M83413-1 electrical
ground
connector
Connect free end of grounding cable to lower torque arm pin on
nose gear (2). If this location Is not accessible, then connect
grounding point).
To ground F-14 aircraft when
2.1.68 F-14 fueling/defueling evolution.
a.
b.
cable
to lower
torque
arm pin on
nose gear (2). If this location is not accessible, then connect
grounding
point).
79
v
w
cl
u
.
t
c-+
w
~
Lb
m
t..
TiI..:.---
MODEL Sd 3H HE LICOPTEk
“~
PA?=]
:%j?’giiikiif,,.-y
TYPICAL
ALTERNATE GIIOUNOING
Q’
CERTIFIED GROUND
I LESS THAN 10 OHMS)
8LDG
FOWE R
Q
:’0.
%~
t
CAUTION
EARTH GROUND POINT
MUST OEfnEE OF
PAINT ANO CORROSION
/j
c
.&
(4)K
FIGURE 2-94.
H3D HELICOPTERS
,
%
MR3413 1
TYPICAL
ALTERNATE
GROUNOING
POINT USING
CONFJECTOR
/
Nangat-based S11-3aircraft grounding, maintenance evolution.
I
—
-—.-—
N.IL,-HDBK-274(AS)
29 June 1990
Supersedes page 1.32of J Novenbt:r 19’53
L32
/
.—-
1983
MIL-l{I)BK-274(AS)
29 June 1990
137
m
.
0-!
I
N
EXTERNALACPOWEfl
RECEPTACLE
MAIN LANDING
GEAR
[
)~T–--\~
I
‘GROUNDING
W( (3’)
w
m
CONNECT
CABLE
TO
u
z:
023IJJ U-J
w
BLDG
POWER
\
CERTIFIED GROUND
(LESS THAN 10 OHMS)
CAUTION
EARTH GROUND POINT
MUST BE FREE OF
PAINT
FIGURE 2-99.
ANO
CORROSION
Hangar-based SH-60 aircraft grounding, maintenance evolution.
MIL-HDBK-274(AS)
29 .June 1990
b.
c.
d.
e.
f.
Connect free end of grounding cable to nose wheel axle (2). If
this location is not accessible, then connect grounding cable to
main wheel axle (typical alternate grounding point).
To ground UC-12 aircraft
2.1.126 UC-12 hangar-based maintenance evolution.
2-108) :
a.
b.
c.
2.1.127 UC-12 apron-based maintenance evolution (with MEPP plugged into
aircraft).
To ground UC-12 aircraft when in the maintenance evolution on the
nnrnr -Ji,71YE?? pluqged !nt~ ,aircraft. p~cceed as follows (see fl,fiure2-].09):
a.
b.
NOTE : If the MEPP is a diesel engine-driven
following bonding requirement is waived.
c.
d.
e.
type, then a power
type, then the
Connect free end of bonding cable to a bare metal area on.the
MEPP (4).
The following paragraphs provide step-by-step
2.2 Carrier-based aircraft.
procedures for grounding carrier-based aircraft. Note that the word “carrier”*
The
is meant to refer to any ship which supports aircraf~ flight operations.
in the Emr.dbc)gkare valid
:i:rfrnaf? [:!l.ectrl.c<al.
~rounding
procz.‘CIUY(?S presented
for
aircraft
Supersedes
operations
page
on
all
ships.
149 ok .1,
November 19b3
~4 ‘:1
MIL-IIDBK-274(AS)
1 Novenbc: l~d~
1.50
.
m
I
o
d
N
FiIL-HDBK-274(AS)
29 June 1990
NOTE :
COMNAViURPAC/CONNAVAIRLANTINST
31OO.4A REQUIRES SINGLE POINT
PRESSURE FUELING ONLY ON CV/CVN CLASS SHIPS. ALL REFERENCES
TO “GRAVITY FUELING” XN THE ILLUSTRATIONS THAT FOLLOW DO NOT
APPLY TO CV/CVN VESSELS.
Before attaching grouding
cables, ensure that the aircraft has been tied down
and secured to the carrier deck. Tiedown chains cannot be relied upon for
grounding.
A grounding cable must be used to properly implement the grounding
methods presented in this section.
Maintenance evolutions and fueling evolutions are represented for each aircraft
type while the parked and stores loading/unloading evolutions are illustrated for
150a
m
w
I
MIL-HDIJK-274(
AS)
1 November 1983
Ill \
159
a
o
m
.
.
A
MIL-HDBK-274(AS )
29 June 1990
aircraft when in the parked evolution and stores loading/unloading
a.
b.
C.
d.
evolution,
Connect free end of grounding cable to pylon station grounding
a
If grounding receptacles are not accessible, then usi~
2.2.8 Carrier-based A-7 fueling/defueling evolution.
To ground
carrier-based A-7 aircraft when fueling or defueling, proceed as follows (see
figure 2-117):
a.
b.
c.
d.
e.
f.
each end, follow step a, and connect
free end of grounding cable
to nose gear tiedown rin8 (typical alternate grounding point).
If using MEPP, attach bonding cable with M83413-1 electrical
ground connector to nose gear tiedown ring (3).
MEPP (4).
To ground carriez-based A-7
2.2.9 Carrier-based A-7 maintenance evolution.
aircraft when in the maintenance evolution, proceed as follows (see figure
2-118):
a.
b.
c.
cl.
e.
f.
supersedes
(clamp
type)
to a padeye (l).
each end~ follow step a, and connect free end of grounding cable
bonding
cable
with M83413-1 electrical
ground connector to nose gear tiedown ring (3).
MEPP (4).
page 160 of 1 November 1983
160
MIL-HDBK-274(AS)
29 June 1990
2.2.10 Carrier-based AH-1 fueling/defuellng evolutfon.
To ground
carrier-based AH-1 aircraft when fueling or defueling, proceed a6 follows (see
figure 2-119):
a.
Attach grounding cable with M83413-1 electrical ground connecror
\
n
MIL-HI)BK-274(AS)
29 June 1990
161
+
I
(--4
(n
/
OF
Fuf
1 Mozzl
F
\
WARNING
TIE DOWN CHAINS UN
n
NOT
—
BE USED TO GROUND AIRCRAFr,
k
L
/+
m
n
u
m
t.)
o
-n
pv+=I
~~r(
u
r
I
CABLE. CONNE~TO
&ECEpTAcLEIN..WHEELWELL
r
-“/
%GROUNDING
FUELING HOSE
CERTIFIED
\
\
GROUND OR PADEYE
(LESS THAN IO,OW OHMS)
L.)
\
ExT POWERSOUIICE NC.2A OR DECK EME Pf3WER
CAUTION
EARTH GROUND POINT
MUST l?E FREE OF
PAI?JT AND CORROSION
FIGURE 2-117.
Carrier-based A-7 aircraft, fueling/defueling evolution.
A
TO
HOSE
REEL
cRoLINDING
—
MIL-}IDBK-274(AS)
29 .June 1.990
u
I”1983
!;l)per’sf!des
pa,qe i63 of 1 :Joverntx
ib3
—-. —-—-——
M11.-HDBK-27L(AS)
1 November 1983
A64
I
N
MIL-HDBK-274(AS)
29 June 1990
167
-. .———
NIL-tiDBK-274(AS)
29 June 1990
1(!8
\
MUST
BE FREE OF
/
CAUTION
(1)s
\\
\\
n\
“)
EXT POW
FJC2A OR OE
A
<gf~
ExTE.NAI.
PowER
RECEPTACLE
FIGURE 2-131.
-
ubCgA l–
:“:
0
Carrier-based EA-6 aircraft, maintenance evolution.
—..—
.–—
MIL-HDBK-274(AS)
29 June 1990
b.
c.
d.
e.
Connect free end of grounding cable to main gear tiedown ring
cable to bracket inside nose wheel well (typical alternate
grounding point).
ground connector to bracket inside nose wheel well (3).
Connect free
end of bonding cable to a bare metal area on the
MEPP (4).
2.2.23 Carrier-based F-4 fueling/defueling evolution.
To ground
carrier-based F-4 aircraft when fueling or defueling, proceed as follows (see
figure 2-132):
a.
b.
c.
d.
e.
f.
If using MEPP, attach bonding cable wfth M83413-1 electrical
ground connector to main gear tiedown ring (3).
!fEPP (4).
2.2.24 Carrier-based F-4 maintenance evolution. TO ground carrier-based
F-4 aircraft
when in the maintenance evolution, proceed as follows (see figure
2-133) :
a.
b.
c.
d.
‘“
f.
grounding cable with M83413-1 electrical grOUUd connector at
ground connector to ❑ain gear tiedown ring (3).
MEPP (4).
2.2.25 Carrier-based fighter aircraft (F-4, F-14, F-18) parked evolution
and stores loading/unloading evolution.
To ground carrier-based fighter (F-4,
F-14, F-18) aircraft when in the parked evolution and stores loading/unloading
u
MIL-HDBK-274(AS)
29 June 1990
B
J&Ii
\
MIL-HDBK-274(AS)
29 June 1990
182
w
m
I
ON
CAUTION
PADEYE
MUSr BE FREE OF
PAINT ANO CORROSION
(
FIGURE 2-134. Carrier-based fighter (F-4, F-14, F-18) aircraft,
varked evolution and stores loadi:]~/unloadin~ evolution.
MIL-HDBK-274(AS)
29 June 1990
a.
b.
c.
grounding point).
2.2,26 Carrier-based F-14 fueling/defueling evolution.
To ground
carrier-based F-14 aircraft when fueling or defueling, proceed as follows (ace
figure 2-135):
a.
b.
c.
d.
e.
nose gear (2). lf this location is not accessible, then connect
grounding point).
ground connector to lower torque arm pin (3).
Connect free end of bonding cable to bare metal area on the MEPP
(4).
1’0ground carrlex-baheti
2.2.27 Carrier-based F-14 maintenance evolution.
F-14 aircraft when in the maintenance evolution, proceed as follows (see
figure 2-136):
a.
b.
c.
d.
e.
grounding point).
If using KEPP, attach bonding cable with M83413-1 electrical
ground connector to lower torque arm pin (3).
Connect free end of bonding cable to bare metal area on the MEPP
(4).
2.2.28 Carrier-based F-18 fueling/defueling evolution.
To ground
carrier-based F-18 aircraft when fueling or defuelfng, proceed as follows (see
figure 2-137):
a.
b.
c.
to ❑ain gear tiedown ring (typical alternate grounding point).
Sllpcrsedes PaFY ‘<
‘?4 of 1 l{ovembcr 1992
MIL-[l
DBK-274 (AS)
1 !Jovernbcr198]
.!
.
A
u
.——
.—.
MT.L-HDBK-274(AS)
29 June 1990
3.4.4 Servicing aircraft with water, oxygen, and hydraulic carts. Similar
precautions are required to ground and bond the aircraft during water, oxygen,
and hydraulic services. Where metal hoses are used between oxygen or nitrogen
cart and aircraft, bonding is unnecessary.
3.4.5 Temporary grounding.
In areas where no approved static or power
grounds exist, ❑etal rods may be driven into the ground at suitable points
adjacent to the proposed aircraft parking position. For temporary grounds
that may be used for some period of time, these rods should be approximately 8
ft. long and 0.875 in. in diameter.
Care mtist be taken that the rod is not
driven into a place where it will damage underground services.
3.4.5.1 For aircraft operating in the field, a temporary ground may be
obtained by driving a metal rod approximately 3 to 4 ft long and 0.5 in. in
diameter into the ground adjacent to the parked aircraft. This usually
provides an adequate static ground. The quality of the ground depends on the
type of soil and the amount of moisture available.
The ground resistance can
be improved by saturating the area with water.
3.4.5.2 A temporary ground rod that is in use for some time should have its
ground resistance measured on a frequent basis. The resistance should be less
than 10,000 ohms. If it is not, consideration should be given to driving
additional or longer rods In order to reduce ground resistance.
3.4.5.3 In geographical areas covered by deep ice, such as Antarctica,
establish a temporary ground(s) as follows:
a.
Drive a metal rod approximately
diameter Into the ice.
b.
During fueling operations, follow the triangulation bonding and
grounding procedures outlined in the handbook using the
temporary grounding rod (see paragraph 3.4).
two feet long and 0.5 inches in
3.5 Actual grounding problems. The following are excerpts from the Naval
Safety Center files. These narrative sections are reproduced here only to
demonstrate the actual types of problems that are encountered in daily fleet
operations.
3.5.1 Narrative:
“WHEN A.C. AND D.C. POWER WAS APPLIED TO ACFT, THE MAINT
PutS RECEIVED A SHOCK FROM THE SKIN OF TliE ACFT. TROUBLESHOOTING OF THE ELECT
SYS REVLD THAT EXTERNAL A.C. D.C. POWER RECEPTACLE COMMON GROUND WIRE NR P
49AON HAD MELTED INSULATION.
OXIDIZATION AND CORROSION VISIBLE AT THE
TERMINAL ON THE ACFT SKIN WAS THE ONLY APPARENT REASON FOR OVERHEATING. ALL
CONNECTIONS WERE SECURE.”
Comment: Prior to any maintenance action, aircraft must be appropriately
grounded.
“DURING TURli AROUND lNSp pLANE CAPTAIN APPLIED ELECT
3.5.2 Narrative:
POWm UTILIZING THE FLIGHT LINE ELECT DISTRIBUTION SYSTEM. UPON CONTACTING
AIRCRAFT, PLANE CAPTAIN RECEIVED MILD BUT DEFINITE ELECT SHOCK. ELECT POWER
WATER WAS STANDING ON RAMP AS A RESULT OF WEATHER CONDITIONS
WAS SECURED.
Supersedes page 238 of J November 1983
.,.
MIL-HDBK-274(AS )
29 June 1990
CONSISTING OF LOW OVERCAST AND RAIN. INVEST BY PUBLIC WORKS ELECT SHOP PERS
REVEALED BROKEN GROUNDING PLUG WHICH PREVENTED THE CABLE FROM ACHIEVING PROPER
GROUND . THIS INCIDENT REEMPHASIZED THE NECESSITY FOR PROPER HANDLING AND
MAINTENANCE OF FLIGHT LINE ELECT POWER DISTRIBUTION SYSTEM IN ORDER TO AVOID
SERIOUS PERSONNEL INJURY, ESPECIALLY UNDER ADVERSE RAMP CONDITIONS.”
Comment:
Emphasizes need to inspect grounding hardware.
3.5.3 Narrative:
●
’AFTER SHUTDOWN FM FLT, ORB MAN BEGAN PROCED FOR LOADING
MK82 PRACTICE BOMBS ON LJTBD RACKS. AFTER COMPLETION OF JETTISON REL CKS,
JETTISON CART WAS BEING INSTLD IN PORT OUTBD STA. AS CAP AND CART WERE BEING
INSERTED INTO BREECH, CART EXPLODED.
INJURY TO ORB MAN INVOLVED WAS
SUPERFICIAL AND THERE WAS NO DAM TO ACFT.
IMMED AFET INCDT, ORD INVOLVED CICED
BOTH CX2TS TO ASCERTAIN JETTISON ASCERTAIN JETTISON SW POSITION, AND STATED
BOTH WERE IN THE OFF/SAFE POSIT. HOWEVER, ACFT WAS UNGROUNDED.
THE MOST
LIKELY CAUSE OF INCDT WAS THE FAIL OF ORDNANCEMAN TO GROUND ACFT PRIOR TO
EXECUTING LOADING PROCEDURES.O”
Comment:
The next ordnance man may not
be so lucky.
3.5.4 Narrative:
“’ACFTWOULD NOT ACCEPT EXT DC POWER FOR START. UPON
REMOVAL OF DECKING PLT SIDE, DISCOVERED DC EXT POWER RECEPTACLE GROUND LEAD
WAS NOT ATTACHED.
FURTHER INVEST REVLD GROUND LEAD HAD BURNED A HOLE IN
BELIEVE ATTACHING BOLT WORKED LOOSE
P1OU’NT1NGARM, THUS FREEING THE LEAD.
OVER A PERIOD OF TIME AND CAUSED POOR CONNECTION.
ANY LOOSENESS COUPLED WITH
EXCESSIVE HEAT GEM BY HIGH CURRENT CAN RESULT IN THIS SIT.”’
3.5.5 Narrative:
“WHILE PERFORllING BEFORE START CHECKLIST WITH EXT D.C.
EXTERNAL
PWR APPLIED, CREW NOTICED SMOKE COMING FROM BENEATH PLTS DECKING.
PWR IMMED SECURED. T/S REVLD LOOSE GROND WIRE FOR DC EXT PWR RECEPTACLE.
REPLACED GROUNDING WIRX.”
3.5.6 Narrative:
“JUST BEFORE LIGHT OFF, ON START OF NO. 2 ENG, PLT
SMELLED ELECTRICAL FUMES AND NOTICED SMOKE COMING FROM UNDER HIS DECKING. HE
SHUTDOWN BOTH ENG AND SECURED ACFT.
TROUBLESHOOTING REVLD DC EXT PWR RECPT
GROUND WIRE LOOSE, BURNING THRUGH ATTACHING STIUNGER.’”
Comment: Para 3.5.4, 3.5.5 and 3.5.6 are typical of many reports and
illustrate not only the need for constant vigilance but the serious
consequences that poor maintenance will cause. Any aircraft fire, especially
onboard a carrier, can be disastrous.
“WHILE DEFUELING, VAPOR WAS OBSERVED IN THE STBD WHEEL
3.5.7 Narrative:
THE FOUR PRIMARY
WELL, INVEST REVLD ALL FOUR ENG HRD BOTTLES HAD DISCHARGED.
STATIC ELECTRICITY BUILD-UP CAUSED BY IMPROPER GRND
CARTRIDGES WERE EXPENDED.
OF FUEL TRUCK TO ACFT. THE FUEL TRUCK TO ACl?T GROUNDING WIRE WAS CONNECTED ‘IO
THE LANDING GEAR SCISSORS STRUT, VICE THE GROUNDING KNOBS PROVIDED ON THE
FOlt’k-.ARD
Sll)h OF Tt-iELAiii)lNGuMR.
TlilS SG1SSUK5 S’ILUT lS PA_ll~TLDAAN3 F’OSSlllL’i
PROPER GROUNDING PROCEDURES HAVE BEEN
COULD HAVE CAUSED AN INPROPER GRND.
STRESSED IN THE CMI). MAINT ERROR SQD.”
Comment: This illustrates not only the need to ❑ake sure that the bonding
cable is attached to a clean metallic surface but the need to do an even
better job of stressing these Important requirements.
[email protected](!
239
of
J. t?ovt?aber
1983
239
MIL-HDBK-274(AS)
29 June 1990
3.5.8 Narrative:
“WHILE TROUBLESHOOTING A FUEL QUANTITY DISCREP,
ELECTRICIAN, AE2 SOUCHAK, RECEIVED AN ELECTEUCAL SHOCK WHILE HANDLING A CANNON
PLUG IN FLAP WELL, INVESTIGATION REVLD THAT ACFT WAS NOT GROUNDED (NOR
REQUIRED TO BE).”
Comment: Cannot agree with the comment *’(nor required to be).”
requirements should be revmitten.
The local
“*WHILE FIJnING FOR TMINING FLIGHT, LIGHTNING STRUCK IN
3.5.9 Narrative:
CLOSE PROXIMITY TO AIRCRAFT AND FUEL TRUCK. OF THE TWO CREWMEMBERS FUELING THE
AIRCRAFT, ONE WAS KNOCKED TO THE GROUND AND THE OTHER LEFT DAZED BUT STILL ON
HIS FEET. THE DHVER OF THE FUEL TRUCK WAS APPARENTLY UNAFFECTED.
THE
FUELING OPERATION WAS SECURED AND THE CREWMEHBERS WERE TAKEN TO THE HANGAR
AREA WHERE CORPSMEN CONDUCTED AND INITIAL EXAMINATION.
THE CREWHEMBERS WERE
SUBSEQUENTLY TUSPORTED
TO THE MEDICAL CENTER AND LATER RELEASED WITH NO
APPARENT INJURIES*
BECAUSE ACCEPTED AND PROVEN SAFETY PROCEDURES WERE
FOLLOWED, A TRAGEDY OF IMMENSE PROPORTIONS WAS UNDOUBTEDLY AVERTED. ALTHOUGH
THE SKY WAS OVERCAST WITH SOME CUMULUS CLOUDS IN THE AREAS, THERE WAS NO RAIN
OR LIGHTNING ACTIVITY IN THE AREA. AS A RESULT, THE DRIVER AND CREWMEMBERS
ALL WERE SATISFIED THAT CONDITIONS WERE SAFE FOR REFUELING.
AT FIRST, IT WAS
BELIEVED THAT THE AIRCRAFT HAD BEEN STRUCK BY THE LIGHTNING; HOWEVER, A
THOROUGH INSPECTION BY QA PERSONNEL REVEALED NO DANAGE OR OTHER INDICATION
THAT THE AIRCRAFT SUSTAINED A DIRECT HIT OR CONDUCTED ANY PORTION OF THE
CHARGE . NO DAMAGE TO THE FUEL TRUCK WAS IN EVIDENCE OR LATER REPORTED BY THE
FUEL FARM. FOLLOWING THE LIGHTNING STIUKE, IT WAS NOTED THAT THE GROUNDING
WIRE HAD NUMEROUS BURN SPOTS AND WAS SMOKING. FURTHER INSPECTION OF THE
GROUNDING WIRE REVEALED THAT IT CONDUCTED A SUBSTANTIAL ELECTRICAL CHARGE AS
EVIDENCED BY DISCOLORED WIRE, CRYSTALLIZED METAL, AND MILTED POLYMER COATING.
DURING THE INITIAL EXAMINATION BY CORPSMEN, ONE OF THE CREWMEMBERS COMPLAINED
OF A TINGLING SENSATION IN HIS RIGHT ARH. SUBSEQUENT INVESTIGATION REVEALED
THAT HE WAS HOLDING ON TO THE FUELING NOZZLE AT THE TIME OF THE STRIKE. THE
OTHER CREWMEMBER INITIALLY HAD BLURRED VISION POLLOWING THE STRIKE. IT IS
BELIEVED THAT THIS WAS PROBABLY CAUSED BY HIM HITTING HIS HEAD ON THE
UNDERSIDE OF THE WING ROOT AT THE TINE OF THE INCIDENT.
AFTER THOROUGH
INVESTIGATION BY THE AVIATION AND GROUND SAFETY OFFICER, IT WAS DETERMINED
THAT ALL APPLICABLE DIRECTIVES AND REGULATIONS WERE STRICTLY ADHERED TO BY ALL
PERSONNEL AND COMMANDS CONCERNED AND AS A RESULT, FURTHER SUBSTANTIATES THE
VALUE OF PROPERLY GROUNDING THE AIRCRAFT AND FUEL TRUCK DURING FUELING
OPERATIONS.” This says it all - it is up to you to READ AND HEED:”*
Comment :
None required.
3.6 Measurement of static ground and electrical power ground points.
Ground resistance measurements should be taken at periodic intervals to ensure
that these measurements are made during different seasons over a period of
years. A 15-month interval is recommended, although local site conditions may
dictate other measurement intervals.
of the previously
3.7 Grounding hardware/receptacle considerations,
In all
mentioned grounding procedures and considerations the receptacle is the
preferred method of connection.
Care must be taken to ensure that the
receptacle is in good condition. Any evidence that the mating connection is
loose indicates t~at the receptacle is defective and it must be replaced.
Supersedes page 240.of 1 November 1983
240
MIL-HDBK-274(AS)
29 June 1990
.
Periodically, all receptacles must be inBPected and their resistance to the
aircraft structure should be measured and found to be less than 0.1 ohm. An
should be inserted in the receptacle and found to be firmly
MS 3493 plug
seated. The pull required to withdraw the plug should be between 8 and 14
lb. A pull of less than 8 lb indicates a weak or damaged receptacle; a pull
In either case, the
exceeding 14 lb may indicate a corroded receptacle.
receptacle must be replaced.
Additionally, the complete cable must be
maintained in good electrical condition.
CAUTION :
Use of alligator clips or braided panel strap to ground or bond
aircraft and support equipment is prohibited.
3.7.1 If a grounding receptacle is not avatlable, an approved grounding
cable constructed in accordance with MIL-c-83413/l or /3 (with KIL-c-83413/7
clamps, as applicable) must be used. Care must be taken that the clam~type
connector, if used, conforms to MIL-C-83413 and must be checked for weak
spring, deformed or rusty jaws, or any other defect which would prevent a good
connection.
3.8 Grounding hardware military specification reference list. Grounding
hardware military specification sheets are listed in Section 1, paragraph 1.2.
241
—-—
—
MIL-}iDBK-274(AS)
1 November 1983
SECTION
4.0
This section provides theory, background, and information necessary to understand
the rationale behind the requirements for aircraft grounding and bonding. Theory
and equations associated with both electrostatic charge generation in aircraft and
grounding effects are discussed. The different aircraft scenarios or servicing
situations are introduced with emphasis OLI the hazards that can be encountered.
4.1 Electrostatic theory. Static electricity, by definition “electricity at
rest,” consists of opposite electrical charges that are usually kept apart by
insular~r~.--Potential differences involved may amount to thousands of volts.
However, the flow of electricity during generation and accumulation is small, in
the range of millionths of an ampere. A primary manifestation of static
electricity is the discharge or sparking of the accumulated charges. Static
electricity is generated by the separation of like or unlike bodies. Electrostatic
charges, positive and negative, always occur in pairs. They become evident when
these pairs, having been in contact with each other, are separated. For significant
potential to be developed, the bodies holding the charges must become, and remain,
insulated from each other. Insulation may occur through complete physical separation
of the bodies or because at least one of the bodies is an Lnsulator.
scenarios are considered ir.
this manual:
a.
b.
c.
d.
Stores handling (including ordnance)
?laintenance (flight line and hangar)
Fueling
Parked
Potential hazards considered during each scenario are:
a.
b.
c.
d..
e.
Static electrical shock to personnel
?ower system electrical shock to personnel
Ordnance misfire and/or inadvertent ordnance or stores release
Fuel vapor ignition
Damage or upset to electronic subsystems
4.3 Energy sources. The source mechanism and source magnitude of the electrical
energy is critical in assessing the possible occurrence of a hazardous situation.
The following energy sources are co be considered during the aircraft evolutions of
stores handling, maintenance, fueling, and aircraft parked:
a.
h.
Static
● Tribaelectric
. Induced
● Friction
Power
. Ground fault
● RF electromagnetic
energy
. LighLning
242
F1lL-HDBK-274(AS)
1 November 1983
4.6.1.5 These values exceed the threshuld hazard values for ignition for fuel vapor.
Therefore, fuel vapor ignition should be considered during fuel transfer. For the
electrically isolated aircraft, fuel vapor ignition, equipment upset, and reflex shock
reaction by personnel must be considered.
4.6.1.6
activity.
The source level has been established
Energy levels may then reach
~.
as clue to charge induced by ..Storm
l/2cv2 = 1/2 (0.005 WF)(60
kV)2 =9J.
These levels exceed threshold values for all hazards:
4.6.2 Time duration considerations.
Some of the phenomena cited in paragraph 4.6.1
are transient in nature. Knowledge of their duration is necessary to assess them as
realistic hazards. Induced voltages, friction voltages, and voltage buildups following
fueling are considered transients.
4.6.2.1 Using the ungrounded aircraft resistance of 40 Mf), an aircraft capacitance
to ground of 0.005 pF, and a safe voltage limit of less than 30V, the following time
durations were computed from:
t
= RC in
Ei
~
()
where t = time to reach E
s
after removal of source
R=
aircraft resistance to ground
c=
aircraft capacitance to ground
‘i=
initial (source) voltage
Es= safe voltage level
Transient Source
E. Source
M~gnitude
Friction
After-fueling potential
Induced
27.0 kV
2.5 kV
60.0 kV
Time
to
Es
1.36 sec
0.88 sec
1.52 see
4.6.2.2 Any transient is objectionable from a safety standpoint. AS stated earlier,
heart action discoordination (fibrillation) threshold levels have time durations as low
as 0.2 sec. Thus , the duration of even the shortest of the three transients considered
is unacceptably long.
4.5.3 —..-.
Haz~T(ls.
11’.
~round?i ;)~r~rat”tln~l$:he ~:]:l~i~~~edtu L2 in jeopardy from tl?~
....—
indicated energy source, since at least one (and generally more than one) hazard
threshold level is exceeded during each scenario. These results are
,. ,. :
,,
..—
——
MIL-HDBK-274(AS)
29 June 1990
summarized in table 4-V below. The possibility of these hazardous events
However, each is
occurring is ensured by the physical data available.
dependent on a number of factors which may occur simultaneously only very
rarely (for example, the refueling of an aircraft with 40 M
impedance to
earth, a fuel spill, and an electrical spark located at the right point in the
volume
of fuel vapor or ~sted fuel to cause ignitiod.
h any single
one-time event, such as an aircraft repair or refueling operation,
consideration could be given to the fact that hazardous combinations appear so
8eldom that they may be neglected.
However, when consideration IS given to
the number of naval aircraft involved, the rapid tempo of operations, the fact
that these are military operations (not always conducted under ideal
conditions), the high cost of equipment, and the threat to personnel safety,
electrical grounding for safety becomes an imperative requirement.
Electrical
airframe grounding, like safety belts in automobiles, is statistically
indicated by, among other things, the vast numbers involved.
TABLE 4-V.
Potential hazard
.-————
. relationship.
Scenario
to enerpv sources and scenarios.
“.
Energy Source
Atmospheric
Fuel
induced
trans
fields
External
power
system
Tribo
Friction
Ma~.ntenance
AD
ADE
-,
Fuel
AD
ADE
ACDE
Stores
Handling
AD
ACE
ACE
BDCE
Park
AD
ACDE
ACDE
Ilcl)li
where:
A =
B =
C =
D =
E=
ADE
ACDE
Static shock to personnel
Power shock to personnel
misfire/releaee
Ordnance IiED/stores
Fuel vapor ignition
Electronic equipment damage
,
Lightning
BD
BCDE
BCDE
BCDE
~IL-HDBK-274(AS)
1 November 1983
000
JPc
.,.,..
.1
.. ..:,.,
.
,...,
.
WATER PIPE SYSTEM
IMETALLIC)
OR
EXTENSIVE
GROUND
SY~EM
(/
+
.’ 7....,.
,.,....
...
“.
. ... . ..
u
1-
FIGURE 5-6.
100FT
(30.5m)~
Two-terminal
method test setun:
——
..
271
MIL-HDBK-274(AS )
~~ June 199fl
c.
d.
Locate a large, unpainted, metal water pipe at least 100 ft
(30.5 m) from the ground point being evaluated and connect test
lead C from the tester to this water pipe.
Adjust the resistance dials on the tester until the indicator
dial is centered (zeroed) on the scale. When the dial is
centered, the resistance value (in ohms) of the ground point
being evaluated can be read on the tester’s digital readout.
5.4 Schedule for resistance testing of ground points. It is recommended
that resistance measurements of a facility’s ground points be performed
periodically in order to determine if there has been any degradation of the
grounding system. It is important to verify that the resistances of the
ground points are below recommended maximum values in order to minimize
likelihood of injury or damage. The recommended maximum resistance values
are: less than 10 ohms for a power ground point and less than 10,000 ohms for
a static ground point.
5.4.1 The recommended time interval between resistance testing is 14
months. This ensures that over a 6–year period the ground points will be
tested during all seasons, thereby providing a profile of seasonal resistance
Depending on the number of ground points to be measured, it might
variations.
be more feasible to employ a rotational method, rather than measure all of the
points in a single time span. For example, if the facility were divided into
SC‘;f?!l
:Pctfcll”,,
s , t~,e w;+sllr~!rlwnf
bIf:l I ‘.:1
!)I.i:dti:lt”l?dS’,’eryLwf; Lgl:l:.:!)g
!.;;!:}:
i[~.!J
different section.
5.4.2 The task of measuring ground points normally comes under jurisdiction
of the public works department of the facili~y. Additionally, their
responsibilities will include setting up and carrying out the test schedule.
5.5 Identification of ground points. It is recommended that ground points
already measured should be Identified in the ❑ anner Indicated in figure 5-7.
This identification indicates to personnel that the ground point Is
satisfactory.
points. Mooring eyes (also
5.6 The use of mooring eyes as static ground
referred to as padeyes) may be used as static ground points provided that they
have been measured and identified in a proper manner (see paragraphs 5.3 and
5.5). Surveys (AIR-5181-1OOO) have indicated that samplings of the resistance
values of mooring eyes showed them to be under 10,000 ohms and therefore
acceptable as static ground points. Mouring eyes selected for use as static
grounds must have their resistance measured and verified at intervals
specified in paragraph 5.4.1.
5.6.1 Figure 5-8 shows typical mooring eye installation details.
Additional information is available in !LiVFACENGCO?lTech&lcal Specification
TS-02614. At some facilities, a stainless steel bead has been welded to the
buildup
(,11 L},L
upper exposed area (Jitl]emooriug t:yt!. :ilis pL-eY’eIIL.a cur:osicJu
of providing a poor ground.
mooring eye and reduces its ]ikeli}lood
,,,,
..,L
MXL-HDBK-274(AS )
29 June 1990
SECTION 6
6.0
INFORMATION FOR GUIDANCE ONLY.
6.1 Changes from previous Issue. Vertical lines or asterisks are not used
In this revision to identify changes with respect to the previous issue due to
the extensiveness of the changes.
6.2
Subject term (keyword) listing.
Aircraft
Airframe
Cable
Electrical bonding
Electrical grounding
Electrical resistance
Maintenance
Procedures
Safety
Custodian:
Navy - AS
Preparing Activicy:
Navy - AS
(Project EMCS-N105)
277
—-—

MIL-HDBK-274 - Barringer and Associates, Inc.

Transcription

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