TM 1-1520-238-23
1-402.26
Change 11
1.137.
SPECIAL INSPECTION CHECKLIST – continued
Helicopter Serial No.:
Date:
Area
No.
Special
Inspection
No.
REQUIREMENT
EVERY
Item
Status
5
54A
50 HOURS
INSPECT CLUTCH MOUNTING PAD FOR CRACKS AND CORROSION.
Inspect clutch mounting pad, with the PTO clutch installed, for cracks and corrosion.
None Allowed.
CHECK CLUTCH HOUSING BOLTS FOR PROPER TORQUE.
Check clutch housing bolts for proper torque (50 inch pounds)
5
54B
50 HOURS
PERFORM APU MOC
WARNING
When the APU driveshaft is rotating, maintenance personnel
should stay clear of the APU, driveshaft and PTO clutch catwalk
area while performing maintenance due to potential catastrophic
failure of the PTO clutch. Catastrophic failure of the PTO clutch
can cause extensive damage to the catwalk area and personnel
injury.
CHECK FOR OIL LEAKAGE.
Check for oil leakage from covered port with APU running. Replace clutch if leakage
exceeds one drop per minute.
4
55
250 HOURS
CHECK TORQUE OF TAIL ROTOR FORK NUTS
SPECIAL INSPECTION
a. If nut rotation does not occur before 600 inch-pounds, verify proper
indexing of tail rotor fork no later than the next 250 hour phase inspection.
b. If rotation of any nut occurs before 600 inch-pounds determine if tail rotor
fork is properly indexed.
c. If tail rotor fork is not properly indexed, go to paragraph 55.G. If tail rotor
fork is properly indexed and there was rotation of any nut during the
torque check, do the following:
(1) Remove tail rotor fork. NOTE: Axial wear that does not penetrate
through the cadmium plating is not caused for rejection however, if
axial wear penetrates the cadmium plating, the stud must be
replaced.
(2) Inspect tail rotor gear box studs for scoring, radial wear (smiles) and
corrosion.
(3) Check studs for looseness. Replace studs if free play exceeds 0.022
inch.
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