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The Main Landing Gear
If you have purchased the CARF-Models Tutor
landing gear, installation is easy. The Behotec
units are proven over many thousands of flights
in other CARF models designs. The C-50 units
are CNC machined from quality aircraft grade
aluminium guaranteeing smooth, twist free
operation.
The Oleo legs are large 18mm diameter units
designed to take even grass field landings,
coupled with the large 4 ½" main wheels the
CARF set will take most surfaces with ease.
Start by assembling the wheel/brake units onto
the oleo legs. The base of the oleo features a flat
side and curved side. The flat side is designed
to go against the brake unit with a 6mm spacer
washer to allow tyre clearance over the A link
pivot. The A link is designed to be on the front
of the leg. At this stage it is a good idea to
install the outer door attachment ring. Only
lightly tighten the set screw to hold the ring
in place.
During assembly ensure you grind flats on
all undercarriage pins where the set screws
seat. The wheel axle pin benefits from the flat
stopping short of the end, this will reduce the
chance of a lost wheel should the set screw
come loose.
Start by adding flats in the correct position
to match the two set screw positions in the
oleo legs. Tighten the set screws against these
flats and loosely assemble the complete oleo
legs into the yokes. Tighten to a point where
the oleo/wheel assembly can just be rotated.
The retract unit is mounted hard against the
closed end of the mount opening with 3mm
plywood between the mounting lugs and carbon
mounting plate. Cut four lengths of 3mm
plywood from the supplied strip and tack glue
these to the underside of the retract mounting
lugs. (Photo 8)
Composite ARF Tutor T-114 manual – techsupport@composite-arf.com
Place the retract unit into the wing and retract
the leg. Check clearance between the wheel and
gear door ram and mark the four mounting hole
positions with a 4mm drill bit. Remove the units
and drill through with the 4mm bit. Reinstall
the unit and place the four M4 mounting screws
through the clearance holes to check exact
centres match the retract units. When satisfied
open the four holes to 5mm and install the M4 T
nuts supplied, use epoxy to secure them.
Reinstall the retract units and screw in position.
Before grinding flats on the pins to suit the yoke
set screw positions the wheel must be aligned
to be parallel with the wing root, or set with
1 degree toe in. Tip: Use a sheet of A4 paper
placed along the wing root to sight the wheel
flat outside face. Placing a stick across the
face held by bands will aid accuracy further.
(Photo 9)
Once satisfied tighten the set screws with an
L key, tightening as much as possible to mark
the pin. Remove the oleo leg and grind flats
for the set screws to seat against. Install with
a small amount of loctite to stop the screws
working loose from operation on hard surfaces
is recommended.
The leg gear door is hinged with a single flat pin
hinge bonded in position between the door and
cover plate. It is important to file the area where
the hinge sits to allow the hinge pin to be as
close to the outer surface as possible. (Photo 10)
This reduces the gap required between door and
cover plate. Trim one half of the hinge fitted to
the cover plate section to clear the carbon wing
rib. Bond the hinge with epoxy resin, and fix
with self tapping screws if desired.
During the hinging process it is best to hold
the cover plate in position with tape to allow
quick and easy remove for adjustments. Once
the hinging is complete the cover plate can
be screwed home with nine 2.9 x 10 sheet
metal screws.
12
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