mounting pad with dry-cleaning solvent. Repair
MAIN TRANSMISSION INSTALLATION
minor nicks, gouges, scratches, and corrosion
The main transmission installation procedures
pitting on the surface of the mounting pad.
follow the removal procedures in reverse. There
Measure the depth of damage to make sure that
are some precautions to follow during the installa-
blending out the damage does not go deeper than
tion. To prevent damage, carefully guide the main
allowable repair limits. Remove corrosion by light
module into place to clear all parts on the
sanding with aluminum oxide abrasive cloth.
helicopter. Apply antiseize compound to the
Inspect all blended areas using fluorescent
mounting bolts.
penetrant. Crack indications or damage greater
than specified requires replacement of the main
WARNING
module.
Antiseize compound may contain lead. Do
not smoke, drink, or eat when handling it.
Main Module Mounting Feet
Wash thoroughly after use. If accidently
swallowed, do not induce vomiting. Seek
Visually inspect the main module mounts daily
medical attention. Sealing compounds and
for cracks radiating outward from the center of
adhesives are toxic. Use rubber or
the bushings. Check for cracks extending down
polyethylene gloves and goggles. Wash
hands thoroughly with soap and water
from the sides of the mounting feet. If no cracks
before eating or smoking. Avoid breathing
are found either in the mounting feet or the seal-
vapors during mixing, lay-up, or curing.
ing compound, further inspection is not required.
Crack indications will require replacement of the
Avoid breathing dust from sanding or
main module. Repair minor damage as long as
grinding.
the repaired area stays within the specified
To prevent corrosion damage to locator pins
repairable limits.
and supports on the main module, seal pins and
supports from moisture accumulation. Lower the
main module into position on the helicopter
MAIN TRANSMISSION REMOVAL
mounting surface. To ease installation, first line
up the front mounting holes and insert the mount
bolts. Next, line up the rear mounting holes and
To make the main transmission accessible for
insert the bolts. Follow the remainder of the
removal, the removal of other items is necessary.
installation procedures as specified in the MIMs.
First, remove rotor blades and head, swashplate,
and engine air inlets. Next, remove the left and
TAIL DRIVE SHAFT INSPECTION
right input modules with accessory modules
Inspect the shaft for scratches. Blend out
attached. Remove all electrical connections and
scratches with crocus cloth. Replace the shaft
harnesses, and all oil and hydraulic lines.
Disconnect and support the tail rotor drive shaft.
section if the damaged or blended area exceeds
To prevent damage to the tail rotor and drive
specified limits. Inspect flexible couplings for
nicks or dents. Blend out dents and nicks on the
shafts while the tail drive is disconnected, make
edges of individual disc, and replace the coupling
sure the tail rotor does not rotate. Remove fore
if the damaged or blended area exceeds specified
and aft bell crank support mounting nuts, bolts,
limits. Inspect each flexible coupling for disc
and washers. Install a lifting eye on the main
rotor shaft. Remove main module mount bolts,
separation. Each disc assembly may have disc
separation or buckling, provided there are no
and raise the main module clear of the heli-
kinks, sharp bends, or cracks. Replace the entire
copter. Lower the module onto an adapter and
coupling if specified limits are exceeded. Inspect
secure with the appropriate bolts, washers, and
the plates in the coupling washer area for wear.
nuts.
Replace the entire coupling if any wear is found.
Inspect the couplings for cracks in the disc. Check
NOTE: The main transmission main
areas close to bolts and special washers. Replace
module weighs about 750 pounds. With all
the coupling if cracks are found.
equipment installed, it weighs 1,200
pounds. The main transmission with the
TAIL DRIVE SHAFT REPAIR
rotor head and equipment installed weighs
Remove paint, dirt, and grease from the
about 2,749 pounds. Be sure to use a hoist
damaged area. Use a cloth moistened with methyl
with suitable weight capacity.
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