TM 1-1520-238-23
Change 9
1-379
1.137.
SPECIAL INSPECTION CHECKLIST – continued
Helicopter Serial No.:
Date:
Area
No.
REQUIREMENT
EVERY
Item
Status
Special
Inspection
No.
2,4,6,7
17
ENGINE OVERTORQUE OR ROTOR UNDERSPEED.
If cracks are suspected, perform nondestructive inspection (TM 1-1520-264-23).
125% or below single-engine overtorque with engine failure - No inspection
required.
125% or below single-engine overtorque without engine failure - No inspection
required.
126% to 130% single-engine overtorque with engine failure:
a. Remove main transmission input drive shaft and couplings on overtorqued
side. Check shaft, couplings, and all drive bolt holes for cracks,
enlargement, deformation, and other indications of overstress.
b. Check overtorqued engine nose gearbox and main transmission for cracks
or oil leakage.
c. Remove overtorqued engine nose gearbox oil filter and main transmission
oil filter. Internally check each filter for metallic particles (chips). If chips
are evident, perform the following steps:
(1) Take “hot” oil samples from engine nose gearbox and main
transmission.
(2) Flush engine nose gearbox and main transmission.
(3) Flush main transmission (para 1.32).
(4) Ground run aircraft for a minimum of 15 minutes.
(5) Inspect engine nose gearbox and main transmission filters.
(6) If no chips are found, resample after approximately 5 flight hours.
126% to 130% single-engine overtorque without engine failure:
a. Perform steps a. thru c. listed for 126% to 130% overtorque with engine
failure.
b. Check tail rotor drive shafts for cracks, deformation, and other indications
of overstress.
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