Throttle and Choke Assembly Safety Directive

Choke and Throttle assembly Safety Directive
Apollo Delta Jet AS-III912S
Apollo orth America, Inc.
Feb 02, 2008
Requirement: Mandatory
Introduction:
There have been a few instances of cruise hand throttles stopping to function in the Delta
Jet weight-shift-control aircraft and there is no way to fix the friction on the existing
throttle quadrant. The only fix is to replace the part. However, the same problem seems to
happen again in time if the part is simply replaced with new one of the same type.
Hence Apollo North America has developed a new hand throttle quadrant for the Delta
jet that we believe is superior to the older one. The safety implication of this problem is
that sometimes the hand throttle would stick and never go back quite to idle making
landing the aircraft more involved if the cruise throttle was being used, as the aircraft
tends to float for longer durations with excess thrust being produced by the propeller.
The choke assembly and choke lever is also recommended to be replaced because its
placement currently is under the dash out of sight. We have had instances of unfamiliar
pilots who don’t read the Aircraft Operating Instructions before operating the aircraft and
are lost as to where the choke lever is located. Also, when told by the familiar instructor
that the choke is under panel, they tend to think that the BRS handle may be the choke.
This of course is a cause of concern as no one wants to engage the BRS handle without
any good reason standing on the ground.
As such this Safety directive is being released to mandate a change to both throttle and
choke assembly systems.
Scope:
All Delta Jet AS-III trikes delivered prior to Jan 1st, 2008.
How to Comply:
Get the kit from Apollo North America, Inc. and follow instruction in this safety
directive. Compliance is mandatory and should be done within the next 15 flying hours or
by June 15th, 2008, whichever comes first. The aircraft should not be allowed to be flown
without complying with this bulletin after that. A LSA-Repairman-Maintenance rating or
higher is needed to attempt this Safety Directive. It is assumed that the mechanic is
familiar with soldering and other general aircraft maintenance techniques and norms.
Tools eeded:
1)
2)
3)
4)
5)
6)
7)
8)
9)
140 Watt minimum soldering gun with a clean tip
OATEY liquid soldering flux, soapy water bottle
Straight file, some medium and fine grade sanding paper
Dremel cutting tool (Hacksaw blade can be used in lieu of, per mechanics
preference)
Paper tape, flash light, sharpie pen or pencil for marking, small wooden skewer
stick or like to apply epoxy mix on fiberglass (or use screwdriver tip)
Cutting pliers or dykes, small vise-grip pliers, needle nose pliers
Cable cutters
Uni-Bit step drill bit with a drill and drill bit set
Wrench set
10) Screwdriver set
11) 912 Carb Sync tool for synching the carbs afterwards (Lockwood Aviation)
Choke Splitter Installation
1) Remove all components of existing choke cable system from aircraft.
2) Locate and mark position on port side of dash panel to drill 7/16” mounting hole.
Drill hole with uni-bit step by step to achieve full size. “see picture”
Fig 1
3) Install new t-handle choke cable and secure with inverted star washer and nut.
Tighten snug not to deform or crack fiberglass.
4) Route cable down and along bottom of trike body as shown in picture and fasten
to fiberglass with supplied plastic retaining clamp and #6 SS truss head screw and
lock nut. Note the two points of attachment forward and midship.
Fig 2
5) Locate and disassemble splitter by removing #4 screw from forward end cap
(without cables). Verify choke handle is in closed position then measure exposed
solid wire cable and see that 4 inches (10 cm) is exposed; check clearance in
cylinder for length. Remove slider from cylinder and place onto solid wire cable.
Note already included and installed multi-stranded cables in slider and only
remove slider from cylinder enough to allow easy access. Place copper retaining
barrel (provided) onto wire and solder in place with supplied acid core solder. If
necessary use OATEY liquid soldering flux (no paste flux should be used). Clean
solder connection with soapy water, pat dry with towel and place a drop of
corrosion inhibitor such as “ACF 50” to insure a lasting connection. Reassemble
the choke splitter.
6) Route stranded cables back and up to appropriate positions on engine to the choke
circuit on the carbs. See picture. Slider assembly can be mounted to cockpit tube
via supplied zip ties at location shown (left or port side of the seat frame towards
the back).
Fig 3
7) Install new choke levers onto carburetors careful not to cross tread nuts on brass
shaft. Attach cables as prior installed and adjust for full travel. Test function of
control handle on dash for ease of operation and twist position stop as operated
by pilot.
8) Existing choke springs will need to be shortened to function properly on new
lever arms. This is done by use of small needle nose pliers. Grasp the long end of
spring just at the loop on the main straight part. Carefully bend 180 degree bend
back over existing bend. This should shorten the spring by 3/16” and can be cut
to remove the double loop (circle end). Now the tension to return the lever to the
stop should be adequate; if not careful adjustment can be applied.
Fig 4
Routing of the choke cable housing from the splitter on the seat frame has to be done
in such a way so as to not have any sharp turn radius and the following rough sketch
can be used as a guide as to how its recommended to be done.
Fig 5
Throttle Cable Installation
1) Remove existing throttle and cable system from trike. Note that the plastic handle
will come off the hand throttle handle with a little force; simply pull outward to
remove. It may require a little effort but rest assured it will come off. The following
shows the existing hand throttle holes and slot.
Fig 6
2) Locate the new hand throttle assembly and remove the cover plate which is secured
with 4 SS screws. The cover plate will be used as a template for the new throttle
location. We used the center of the fuel cap as a reference point. Cover the location
on the body where the hand throttle is installed with blue masking tape to protect
the aircraft finish and for ease of marking.
3) From the fuel cap center, measure forward 21- 7/8” and place a perpendicular line
segment relative to plane formed by the top of the body at the seat frame (call it
line 1). This should be the starting point and where the two aft screws of the throttle
plate are located. Next mark a line parallel with the top of the body 1-3/8” down
and forward of line 1. This will be the bottom of the new throttle lever opening slot.
Refer to Fig 7. With these lines in place over lay the cover plate and mark the four
mounting holes and lever slot.
4) Using a # 40 drill, drill the four mounting holes using outer hand throttle cover
plate as template. Then two more, one at each end of the throttle slot. Next with the
uni-bit carefully enlarge the holes to 3/16” assuring they remain in the correct
position aligned with the cover plate.
Fig 7
5) Cutting the slot for the throttle lever requires skill with a dremel tool (hacksaw
blade can be used in lieu of dremel tool on mechanics preference) and flat file.
Carefully use a dremel cutting wheel to cut out the slot leaving tolerance for filing
to adjust the accuracy of the slot. Spending a little extra time will provide a better
fit and much cleaner results. Remove the throttle knob for installation and verify
the fit by assembling in place and adjusting any misalignments. Once satisfied with
the proper fit the upper original slot can be filled in.
Fig 8a
Fig 8b
6) First clean the old slot by sanding away any paint or dirt that may contaminate or
interfere with adhesive quality of epoxy. Then using standard clear packing tape,
apply a piece on the inside of the trike body. This will act as a form to maintain the
epoxy in place while curing. Cut another piece and have it ready for completion of
the patch. Using the supplied five minute epoxy, mix up an adequate amount to fill
the void. Apply the mix into the slot with a small stick or screw driver. Care must
be given as to the correct volume required. Next place the outer piece of tape over
the epoxy filled slot to form a complete seal and avoid having any excess
between the body and the tape. All of the fill material must remain in the old slot.
Within fifteen minutes the tape can be removed and the patch should be complete.
Refer to Fig 7 that shows an epoxy fill patch.
7) The throttle splitter can now be installed with the zip-ties supplied. It should be
placed on the seat tube very near the rear bend starboard side of aircraft. Create a
stand-off by using two long and two short ties. Carefully raise the fiberglass to
allow the plastic tie to fit between the metal tube and fiberglass. This should assure
a trouble free connection between splitter and quadrant.
8) Drill a ¾” hole through top of trike body at seat tube to facilitate adjustment of
throttle friction. See Fig. 9a and 9b
Fig 9a
Fig 9b
9) Install the hand throttle quadrant assembly on the inside of the trike body(refer Fig
10a), placing the cover plate on the outside of the body (Fig 10c), matching holes
and securing with the 4 screws. Adjust the hole drilled in Fig 8a and 8b if necessary
to allow adjustment of friction bolt.
Fig 10a
Fig 10b
Fig 10c
10) Route the throttle cables as shown in the sketch behind the mast and in-front of the
engine. Cables are run congruent to the choke cables (see Fig 5) and installed in the
throttle position on the carburetor. Install cables to engine as per standard
application with cable stops on carbs.
Fig 11a
Fig 11b
11) Solder the very ends so they don’t unravel with provided acid core silver solder
with a decent soldering gun. The soldering gun should be a minimum of 140
Watts, with a clean tip. o paste flux should be used, if necessary liquid
soldering flux like OATEY Liquid Soldering Flux should be used.
12) The throttle cables to the foot throttles should be routed in such a manner so as to
not have any sharp bends in the cable housing and to avoid the storage cavity under
the front seat. The pictures below show the routing of the foot throttle cable
housing as a reference. Cable stop supplied with two set screws should be placed
after the foot throttle pedals so foot throttles can engage the throttle circuit of the
carbs via the splitter. This should be done with care so that there is no “slop” or gap
between the stop and the housing. A small vise-grip plier can be used to lock on the
cable just behind the cable stop, so that the cable stop remains in place while the
mechanic tightens the set screws. Working inside the trike in the front area requires
some flexibility and a flash light pointed in the area being worked on by a helper
will help tremendously. Please note that there should be about 2.5 to 3 inches of
extra throttle cable hanging beyond the cable stop on the foot pedal. The end of this
cable should be soldered with the provided solder so it does not start to unravel.
This is done easiest when the cable is out of the foot throttle but measured in place,
not once the cable stop is put in and mechanic has to bend and work to solder
inside on the front of the trike.
Fig 12a
Fig 12b
Fig 12c
13) Adjust and sync carburetors (with choke circuit completely disengaged) to
airworthy condition as per instructions provided by Rotax. If not sure on how to do
carb synchronization then please visit http://www.rotax-owner.com/expanded.htm
and watch the carb synchronization e-Learning video module before attempting to
synchronize the carbs on a 912 series engine. The carbs may have to be resynchronized once again after the new cables settle in, in a few hours of usage. It is
recommended to lube the insides of the 90 degree Rotax brass cable conduits at the
912 series engine carbs with ACF-50 or lock oil on a regular basis as part of
general maintenance.
14) The choke under panel decal should be removed from the panel.