Hangar 9 Twin Otter ARF Assembly Manual page 24

Step 13
Invert the nacelle and position the engine on the
mounts so the face of the drive washer is 3 1/2 inches
from the firewall.
Step 14
Mark the engine mounting holes on the mounts then
remove the engine. Use a drill motor and 1/8-inch bit
to drill the mounting holes.
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Step 15
Place a #4 steel washer onto each of the 4-40 x 1-inch
Allen head machine screws. Place the engine on the
mount and insert the screws. Slide a second #4 washer
on each screw then thread on a 4-40 nylon locknut.
Use a 3/32-inch hex and 1/4-inch wrench to tighten the
engine to the mount.
Step 16
Prepare a micro servo with grommets and bushings.
Note that the bushings are installed from the bottom of
the servo.
Step 17
Attach a 9-inch servo extension lead to the servo and
secure the connectors with dental floss.
Hint: Apply a very small drop of thin CA to the knot to
prevent it coming loose.
Step 18
Use a #1 Phillips screwdriver to remove the small arm.
Use sidecutters to remove three arms from a standard
4-way arm, leaving one long arm. Install the arm on
the servo as shown.
Twin Otter ARF Assembly Manual