TM 1-1520-238-23
5-98
Change 6
5.19.
MAIN ROTOR HUB RETENTION NUT REMOVAL – continued
5.19.4. Cleaning
a. Clean retaining ring, retention nut, and twelve bolts (para 1.47).
5.19.5. Inspection
a. Check mast, retaining ring, and attaching hardware for cracks. None allowed.
b. Check retaining ring for nicks, gouges, scratches, scoring, and galling.
(1) Defects shall not exceed 0.010 INCH width, 0.010 INCH depth, and 1.00 INCH length.
c. Check bolts and mast for thread damage. None allowed.
d. Check threads in the 12 bolt holes of retention nut for red rust using a x10 power glass.
(1) Rust spots on the plating or blistered plating indicates corrosion or pitting of the steel underneath. If rust is
detected replace retention nut.
e. Check retention nut surface for white powdery deposits which indicate corrosion of the cadmium
plating. Repair per paragraph 5.19.6.
f. Check retaining ring and retention nut for scratches.
(1) Scratches which penetrate less than 0.010 INCH into base metal and which are less than 0.063 INCH wide
are permissible.
(2) Clean scratches (para 1.47).
(3) Touch-up finish scratches by applying two coats of epoxy primer. Use epoxy primer coating kit (item 78,
App F).
(4) Coat part with corrosion preventive compound. Use corrosion preventive compound (item 63, App F).
(5) Scratches which are wider than 0.063 INCH or which penetrate more than 0.010 INCH into base metal
shall be repaired per paragraph 5.19.6.
g. Check retention nut for cracks. None allowed.
(1) If cracks are suspected, perform nondestructive inspection (TM 1-1520-264-23).
h. Check serial number of retention nut.
(1) If serial number is 0212 through 0266 or 005222-53 through 005222-105, replace retention nut.
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