Aircraft Electrical Installation Hands On Workshop

Aircraft Electrical Installation Hands On Workshop
I. Introduction – What we will cover in this presentation
a.
b.
c.
d.
e.
Aircraft electrical installation
Materials
Tools
Techniques
Recommended practices
II. Qualifier
a.
For the Lawyers among us – The Information discussed here does not supersede or replace government
regulations or specifications or the manufacturers’ instructions
III. AC 43.13-2B
a.
b.
FAA Advisory Circular Publication documenting recommended techniques for aircraft maintenance and repair
i. It is an advisory circular not a rule
ii. Paragraph 11 and 12 deal with Electrical and Avionics
How to get it
i. You can download it free from the FAA (www.faa.gov) use “quick find” search for “advisory circulars” then
“AC 43.13-2B”
ii. NOTE: It is a “PDF” file so you will need Adobe Reader
(www.adobe.com/products/acrobat/readstep2.html) if you don’t already have it.
iii. If you download it you will not want to print the whole document, it is several hundred pages long
iv. Or you can buy a hard copy from most aviation book sellers or pilot shops
IV. Wire - Auto and Marine vs. Aircraft wire
a.
b.
c.
d.
e.
Auto wire
i. Is not usually “tinned” or plated with a corrosion resistant coating like tin, nickel or silver
ii. Wire made for automobile applications often has PVC or vinyl insulation which will burn and produce
poisonous fumes
Marine wire
i. Marine wire is usually tinned to inhibit corrosion but also usually uses PVC insulation
Mil spec 5086A Wire (See Picture #1)
i. Relatively thick PVC insulation
ii. Finely stranded and tinned with tin, nickel or silver
iii. Found in most aircraft produced until the late 1970’s
iv. PVC insulation produces Cyanide when it burns and will support combustion
Mil spec.22759 Wire (See Picture #2)
i. Marking MIL-22759/ (number) – (wire gauge)
ii. Teflon or Tefzel insulation
iii. Will not support combustion and does not generate poisonous fumes when exposed to flame
iv. Is always finely stranded
v. Is always tinned with tin, nickel or silver making it highly corrosion resistant
vi. Table 11.11 Open Wiring in 43.13 page Par. 11-89 page 11-40 (See Page 11)
Kapton Wire (See Picture #3)
i. BAD NEWS DO NOT USE!
ii. Plentiful and cheap on the surplus market because it is being removed from commercial and military
aircraft as fast as they can economically get it out.
iii. Cracks rapidly with age and burns like primercord when it gets lit
iv. Several air carrier and military inflight fires and crashes have been traced to Kapton wire
V. Wire Stripping Tools
Page 1
Aircraft Electrical Installation Hands On Workshop
a.
b.
Knife or Chisel type (See Picture #4)
i. Make a good tack hammer (not a good aircraft wire stripper)
ii. Extremely easy to damage wire
“Ring Die” type (See Picture #5)
i. Ideal Tool Co. “Stripmaster” or “Custom Stripmaster”
ii. “Ring Die” type come in several varieties
iii. Be careful of the surplus strippers designed for Kapton wire! the relief for the insulation is smaller
because of the thinner insulation on Kapton wire and will not work well on 22759 wire
iv. The dies are changeable in Stripmasters
VI. Terminating and Splicing
a.
b.
Crimping vs. Soldering
i. Solid wire is highly susceptible to damage from vibration
ii. Houses do not vibrate (much), this is why house wiring is solid or has very large strands
iii. Aircraft wire is very finely stranded to make it vibration damage resistant
iv. Soldering makes it a solid wire for an indeterminate distance beyond the soldered joint or terminal
v. A termination using the correct type of crimp terminal crimped with the correct crimper is the most
reliable and longest lasting connection for a wire in an aircraft application
Crimp Terminals Automotive vs. Aircraft (See Picture #6)
Crimp terminals for auto use
Crimp terminals for aircraft use
Amp calls them “Plastigrip”
Amp calls them “Pre Insulated Diamond Grip” or PIDG
Use Vinyl insulation
Always use Nylon insulation
Do not have a metal insulation grip
Have a metal sleeve for insulation grip
Do not have a brazed barrel for the wire grip
Have a brazed or soldered barrel for the wire grip grip
VII. Crimping Tools (See Picture #7)
a.
b.
c.
d.
VIII.
Crimp depth is important so the wire isn’t damaged in the crimping process
The wire grip and insulation grip must both be crimped at the same time for a proper termination
“Tack hammers” do not give predictable crimp depth and crimp one grip area at a time
Ratcheting dual die crimpers give a predictable crimp depth and crimp both the insulation grip and the wire grip at
the same time to the correct depth
Coaxial Cable
a.
RG-58/(letter) (See Picture #8)
i. Has black PVC insulation , stranded inner conductor with clear nylon or polyethylene insulation
ii. Cheaper versions of this cable (CB Cable) are not ‘tinned” and have a bare copper outer braid and are
highly susceptible to corrosion
iii. Is fine cable other than the “PVC burning thing” until it gets about 5 to 7 years old
iv. Gets brittle with age and begins cracking and absorbing moisture
v. Coaxial cable is used in systems where constant impedance for the length of the cable is vital. When it
absorbs moisture it changes the impedance of the cable in the area where moisture is absorbed
Page 2
Aircraft Electrical Installation Hands On Workshop
b.
c.
RG-400 cable (See Picture #9)
i. RG 58 has been superseded by RG 400 which is a much higher performance cable
ii. Has translucent gold colored Teflon insulation, silver tinned double outer braid and stranded tinned inner
conductor with Teflon insulation
iii. Silver tinned outer braid and inner conductor make RG 400 highly corrosion resistant
iv. Does not become brittle or crack with age due to Teflon insulation
v. Is slightly more expensive but very much worth it for airborne applications
Coaxial Cable Termination
i. All connectors made for RG 58 will fit RG 400.
ii. Crimp connectors are the preferred connectors for our aircraft applications
iii. Crimp connectors are easier to attach properly and are more vibration resistant than “clamp type” that
screw together
iv. Most good quality connectors (Amphenol) have a stripping dimension diagram on the package (See
Picture #10)
v. The hole in the center pin is NOT for soldering in a crimp type connector it is a view hole to verify that the
center conductor is bottomed in the pin
vi. A good quality crimper for these connectors can be purchased for less than $25
vii. Buy some extra connectors and cable, you will need to practice
IX. Wire Support & Securing
a.
b.
c.
Ty Wraps
i. Come in many varieties not all of which are appropriate for aircraft use
ii. Vinyl vs Nylon and telling the difference
iii. Metal tab vs plastic tab
iv. Limitations in high heat areas
v. Minimize blood loss, use flush cutting side cutters to cut off the tails
Lacing Cord
i. Better than Ty Wraps because it is easier on the wire.
ii. Comes in several varieties, waxed, unwaxed, nomex for hot areas etc
iii. Bundle lacing shown in AC 43.13 is good but has drawbacks when maintenance or modification is required
it all comes unraveled!
iv. The skilled technicians at NASA have a better way, this knot as been used on military aircraft, ships and
spacecraft for many years
v. (See Picture # 11) Here is the knot on the wiring bundles on a Gemini space capsule, the entire wiring
harness on the capsule is tied up with this knot
vi. The knot I am going to show you takes the place of individual Ty Wraps (See Picture #12)
vii. More info on the lacing tape here http://www.carwild.net/gudebrod/Braid_Lacing_Tape.htm
Clamps
i. Adel Clamps MS 2919-XX-X
ii. http://www.aeroelectric.com/articles/adel.html (See Page 12 of 13)
iii. General Color code: black or darker color is for cool and/or less chemically threatening areas and red,
orange or yellow is for hot and/or more chemically threatening areas
iv. Nylon Clamps not for hot areas
v. Same caution applies as for nylon and vinyl Ty Wraps
vi. Spacing
Page 3
Aircraft Electrical Installation Hands On Workshop
X. Wire Bundle Routing
a.
b.
c.
Separate Noisy Bundles from Quiet ones
i. Route high current (flap and landing gear motors, landing lights, starters etc.) or noise producing (strobes)
circuits as far as possible away from instrumentation, audio and data circuits
ii. Six inches is good but farther is better
Crossing Angle
i. If you have to cross an audio, instrumentation or data cable with a high current or noisy circuit do it at 90
degrees
ii. This minimizes the electrical coupling between the two circuits
Pay attention to where wiring is in relation to liquid lines (especially fuel)
i. Route wiring ABOVE fuel or other liquid lines so if the lines leak they will not leak on the wires
ii. Do not secure wiring to liquid lines
XI. Wire Protection
a.
Strain relief and environmental protection
i. Heat shrink tubing is great but has some limitations
ii. Regular heat shrink can actually trap moisture under it
iii. Special types of heat shrink are available with gel inside to make it waterproof
iv. Most inexpensive heat shrink is PVC which can burn and make cyanide gas
v. Heat shrink specifically for aircraft use is made from Polyolefin
vi. Protect sharp edges with chafe protection (See Picture #13)
vii. Give yourself service loops at the ends of wires
XII. Wire Marking
a.
b.
XIII.
Do yourself a favor, mark everything so you can find it later
i. Mark both ends of a circuit and if it is a long one every 3 or so feet along the way if it is accessible
ii. White heat shrink with lettering by ball point pen or fine point sharpie works great
iii. Clear heat shrink with paper underneath for marking is also slick way to do this
Dymo, Brother and Brady make inexpensive (<$75) label makers that work great for this
i. Oil and moisture resistant label tape is available for these
ii. These are commonly used for data network cable labeling
iii. Get one that can print in “wrap” format so it can be wrapped around the wire
THE END
a.
That’s all Folks!
Come on up and try what I just showed you
Page 4
Pictures from Slide Show
Picture #2
Picture #1
Picture #3
Picture #4
“Knife or chisel” type stripper
Picture #5
“Ring die” type stripper
Page 5
Pictures from Slide Show
Picture #6
Picture #7
Page 6
Pictures from Slide Show
Picture #9
Picture #8
Picture #10
Picture #11
Page 7
Pictures from Slide Show
Picture #12
Wire Tying Knot
(Way better than a Ty-Wrap!)
PLACE LOOP
BEHIND BUNDLE
Step 1
WIRE BUNDLE
PULL LOOP FROM
SPOOL SIDE IN
FRONT OF BUNDLE
THROUGH FIRST
LOOP
Step 2
WIRE BUNDLE
PULL LOOSE END
IN FRONT OF
BUNDLE
THROUGH
SECOND LOOP
AND PULL TIGHT
Step 3
WIRE BUNDLE
Step 4
HOLD SPOOL
AND PULL TIGHT
HOLD SPOOL
AND PULL TIGHT
PULL TIGHT
WIRE BUNDLE
Page 8
Pictures from Slide Show
Picture #13
Page 9
AC 43.13-1B CHG 1
9/27/01
TABLE 11-11. Open Wiring.
Insulation Type
rating
(maximum)
Rated wire
temperature
(°C)
MIL-W-22759/1
600
200
Fluoropolymer insulated TFE and TFE
coated glass
Silver coated copper
MIL-W-22759/2
600
260
Fluoropolymer insulated TFE and TFE
coated glass
Nickel coated copper
MIL-W-22759/3
600
260
Fluoropolymer insulated TFE -glassTFE
Nickel coated copper
MIL-W-22759/4
600
200
Fluoropolymer insulated TFE -glassFEP
Silver coated copper
MIL-W-22759/5
600
200
Fluoropolymer insulated extruded TFE
Silver coated copper
Document
Voltage
Conductor type
MIL-W-22759/6
600
260
Fluoropolymer insulated extruded TFE
Nickel coated copper
MIL-W-22759/7
600
200
Fluoropolymer insulated extruded TFE
Silver coated copper
MIL-W-22759/8
600
260
Fluoropolymer insulated extruded TFE
Nickel coated copper
MIL-W-22759/9
1000
200
Fluoropolymer insulated extruded TFE
Silver coated copper
MIL-W-22759/10
1000
260
Fluoropolymer insulated extruded TFE
Nickel coated copper
MIL-W-22759/13
600
135
Fluoropolymer insulated FEP PVF2
Tin coated copper,
MIL-W-22759/16
600
150
Fluoropolymer insulated extruded
ETFE
Tin coated copper,
MIL-W-22759/17
600
150
Fluoropolymer insulated extruded
ETFE
Silver coated high strength copper alloy
MIL-W-22759/20
1000
200
Fluoropolymer insulated extruded TFE
Silver coated high strength copper alloy
MIL-W-22759/21
1000
260
Fluoropolymer insulated extruded TFE
Nickel coated high strength
copper alloy
MIL-W-22759/34
600
150
Fluoropolymer insulated crosslinked
modified ETFE
Tin coated copper
MIL-W-22759/35
600
200
Fluoropolymer insulated crosslinked
modified ETFE
Silver coated high strength copper alloy
MIL-W-22759/41
600
200
Fluoropolymer insulated crosslinked
modified ETFE
Nickel coated copper
MIL-W-22759/42
600
200
Fluoropolymer insulated crosslinked
modified ETFE
Nickel coated high strength
copper alloy
MIL-W-22759/43
600
200
Fluoropolymer insulated crosslinked
modified ETFE
Silver coated copper
MIL-W-25038/3/2/
600
260
See specification sheet *
See specification sheet
MIL-W-81044/6
600
150
Crosslinked polyalkene
Tin coated copper
MIL-W-81044/7
600
150
Crosslinked polyalkene
Silver coated high strength copper alloy
MIL-W-81044/9
600
150
Crosslinked polyalkene
Tin coated copper
MIL-W-81044/10
600
150
Crosslinked polyalkene
Silver coated high strength copper alloy
* Inorganic Fibers - Glass - TFE
Page 11-40
Page 10 in Aircraft Electrical Workshop
Par 11-89
Adel Clamps
Everything you ever wanted to know but were afraid to ask
by Bob Nuckolls
I've seen some conversation recently concerning "Adel" clamps and their suitability for use around fuel, high temps,
etc. I've pulled the specs and will excerpt some of their contents as follows:
The "Adel" clamp is more properly called an MS21919 aircraft clamp. The company named Adel built a goodly
portion of the MS21919 clamps back in the 60's (and may still). The term sort of stuck on these devices in spite of
the fact that they are now made by dozens of companies.
The full description for these clamps follows the convention MS21919WXXZZ where:
W = "wedge" feature in cushion that helps prevent escape of small wires out of cushion. Virtually all new
production of MS21919 clamps below size 50 have the wedge feature...
XX characters have the following significance:
DE = Aluminum band, Ethylene Propylene Cushion (212F)
DF = Aluminum band, Nitrile Cushion (212F)
DG = Aluminum band, Chloroprene Cushion (212F)
CE = Corrosion Resistant Steel band, Ethylene Propylene Cushion (275F)
CF = Corrosion Resistant Steel band, Nitrile Propylene Cushion (200F)
CH = Corrosion Resistant Steel band, Silicone Cushion (400F)
CG = Corrosion Resistant Steel band, Chloroprene Cushion (212F)
CJ = Corrosion Resistant Steel band, Fluorosilicone Cushion (450F)
F = Low Carbon Steel Band, Nitrile Cushion (212F)
G = Low Carbon Steel Band, Chloroprene Cushion (212F)
H = Low Carbon Steel Band, Silicon Cushion (400F)
CAUTION - Clamps with low carbon steel bands are not recommended for new design and most were purged from
stocks back in early 80's, however, you never know what might show up in the Fly-Market at OSH so I've included
the "heads up" here.
Cushion Application and Color Information:
Ethylene Propylene - for use in areas contaminated with phosphate- ester hydraulic fluid and other synthetic fluids.
Excellent ozone resistance., Not resistant to petroleum based fluids. Color shall be solid purple.
Nitrile - for use primarily in fuel immersion and fuel vapors. Good ozone resistance. Not resistant to phosphate-ester
based fluids. Not for use on titanium tubing. Color shall be solid yellow.
Chloroprene - for general purpose use in areas contaminated with petroleum based hydraulic fluids and occasional
fuel splash. Excellent ozone resistant. Not resistant to phosphate-ester based fluids. Not for use on titanium tubing.
Color shall be black with a blue identifier patch.
Silicone - for elevated temperature usage in phosphate-ester based fluid and other synthetic fluid contaminated
areas. Unaffected by ozone. Not resistant to petroleum based fluids. Color shall be natural white.
Fluorosilicone - for elevated temperature usage in petroleum based fluid contaminated areas. Unaffected by ozone.
Not resistant to phosphate-ester based fluids. Color shall be solid blue.
Silicone - RED now obsolete and used only on the low carbon Steel
Page | 11
Adel Clamps
Everything you ever wanted to know but were afraid to ask
by Bob Nuckolls
The last characters (ZZ) are digits describing the internal diameter of the closed clamp in 1/16ths of an inch. E.G. an
MS21219WDG4 is aluminum strap inside a chloroprene cushion and sized to support 1/4" diameter bundle of wires,
tubing, etc.
I note that the spec does not speak to the "red" cushions currently being discussed. I recall seeing a number of
clamps with red cushions over the years but quite frankly, I don't know if they were MS21919 or perhaps some other
part number.
UPDATE: All of the "reds" have been purged from Raytheon's stocks, couldn't even find one in the junk boxes that I
had access to. Mr. Sobek says the one he found does carry the part number MS21919H** which tells us it is indeed
the obsolete, low carbon steel version and silicon rubber (not recommended for use where "wet" with hydrocarbons.
Page | 12
Sun & Fun Hands On Workshops
Vendor
Website or Physical Address
Aeroelectric Connection
Amateur Electronic Supply Online
Amateur Electronic Supply Orlando
Retail Store
B & C Specialty Products
Contact East/Jensen Tools (Stanley
Supply Services)
http://www.aeroelectric.com/
www.aesham.com
620-886-3403
800-327-1917
Excellent articles and guides for wiring your airplane
Amateur Radio and Electronic Supplies
621 Commonwealth Ave. Orlando, FL 32803
www.bandc.biz/aircraft-electrical-tools.aspx
407-894-3238
316-283-8000
Amateur Radio and Electronic Supplies
D-Sub, PIDG, Coax and Molex Crimpers, Ideal Strippers
www.stanleysupplyservices.com
800-225-5370
Commercial Electronics Tools, Test Equipment
Digi Key Corp.
Edmo Distributors
Ideal Industries (Stripmaster
Manufacturer)
Matronics Inc.
www.digikey.com
http://www.edmo.com
800-344-4539
800-235-3300
Commercial Electronics Distributor, Tools, Test Equipment
Major Avionics Supplies Distributor
www.idealindustries.com
www.matronics.com
800-324-9571
925-606-1001
Parts for Ideal Stripmaster Stripper Tools
Kitbuilding Electrical Advice and Supplies
Mouser Electronics
Skycraft Surplus Online Store
Skycraft Surplus Orlando Retail Store
Specialized Products
Techni-Tool
Useful Links
www.mouser.com
skycraftsurplus.com
2245 West Fairbanks Ave. Winter Park, FL 32789
www.specialized.net/specialized/
www.techni-tool.com
800-346-6873
321-972-8357
407-628-5634
800-866-5353
800-832-4866
Commercial Electronics Distributor, Tools, Test Equipment
Wire and Surplus Tools
Wire and Surplus Tools
Commercial Electronics Tools, Test Equipment
Commercial Electronics Tools, Test Equipment
Aeroelectric Links Page of useful links to
kitbuilding and electrical suppliers
Direct Link to FAA Website to download
AC 43.13-1B
Gudebrod (Carwild) Lacing Tape
Website where you can get the
presentation from this workshop
www.matronics.com/aeroelectric/Sources.html
Phone #
Content
www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/99861
http://www.carwild.net/gudebrod/Braid_Lacing_Tape.htm
www.edhlund.com
Page 13