TM 1-1520-238-23
Change 9
6-429
6.97.
MAIN ROTOR SUPPORT MAST REMOVAL/INSTALLATION – continued
6.97.6. Repair
NOTE
Surface D is nickel/silver plated. Build
up of black silver oxide on this area is
result of fretting action and is accept-
able. Do not remove black silver oxide.
The inspection criteria below requires
no rework/repair if the limitations
(0.003 INCH) are not exceeded.
a. All surfaces except surface G and H. See step
b for surface H and step c for surface G.
(1) Blend damaged surfaces to a minimum of a
20:1 ratio. Each contiguous blended area
shall not exceed a 2.0 INCH diameter.
(2) Fluorescent dye penetrant inspect repaired
surfaces. No cracks or deformities allowed
(TM 55-1500-335-23). Use fluorescent
inspection kit.
(3) Finish repaired areas as follows:
(a) Surface A, apply primer coating (item 78,
App F) and polyurethane coating (item
141, App F) to repaired area. For inside
diameter apply primer coating (item 78,
App F) to repaired area except for lower
0.5 inch of mast.
(b) Surfaces B, D, E, and F. Apply lubricant
to repaired area. Use lubricant (item 116,
App F).
1 Allow lubricated surfaces to cure for
6 HOURS at room temperature, or air
dry for 30 MINUTES and then cure
for 30 MINUTES at 150 F (66 C).
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M04-520-8A
F
E
D
C
B
A
H
G
