TM 1-1520-238-23
1-402.6
Change 10
1.137.
SPECIAL INSPECTION CHECKLIST – continued
Helicopter Serial No.:
Date:
Area
No.
REQUIREMENT
EVERY
Item
Status
Special
Inspection
No.
6
42
(cont)
d. Inspect wall and bottom areas of each lightening hole cavity using
flashlight and mirror (para 2.88).
(1) Remove dirt, fluid, and debris to prepare surface for inspection (para
1.47).
(2) If no corrosion is observed, treat internal surfaces of four holes (para
1.49).
(3) If surface corrosion is observed, remove corrosion (para 2.88).
(4) Check for pitting on walls and bottom of lightening holes (para 2.88).
(a) If no pitting is observed, treat lightening hole areas (para 1.49).
(b) If pitting is observed, apply impression compound to all surfaces of
each lightening hole (para 2.88).
e. Inspect impressions (para 2.88).
(1) If pits do not exceed depth values in (para 2.88), rework (para 2.88).
(2) If pits exceed the depth values in (para 2.88), replace mast support
base (para 2.88).
(3) Submit a CAT I Deficiency Report.
f. Replace lightening hole covers (para 2.88).
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