TM 1-1520-238-23
6-200.2
Change 9
6.41.
MAIN TRANSMISSION INSPECTION – continued
l. Check magnesium cast transmission housing for damage, depth not to exceed 15 percent of material
thickness.
(1) Where material thickness cannot be determined, maximum allowable depth is 0.050 INCH in a 1
SQUARE-INCH area. Use depth gage.
(2) After blending, magnesium must be corrosion protected. Touch up (para 6.43).
m. Check generator seal on spline adapter for leakage. (None Allowed).
(1) Replace seal if leakage exceeds ONE DROP PER MINUTE (para 6.43).
n. Check tail rotor drive flange for serviceability.
(1) Check for nicks, burrs, gouges, and corrosion. Except for surfaces identified below, depths less than 0.020
INCH before blending are acceptable. Use depth gage.
(2) Check packing groove for scratches, nicks, gouges, and corrosion. Damage of 0.004 INCH or less may be
blended out at a 30:1 transition ratio. Use depth gage.
(3) Check for fractures and/or cracks. None allowed.
(4) Check identification marking. Must be readable.
(5) Check coupling mounting diameter. Minimum diameter 2.1236 INCH. Use caliper set.
(6) Check diameter of pilot between shaft and gear. Minimum diameter 1.6215 INCH. Use caliper set.
(7) Check diameter of pilot between gear and plug. Minimum diameter 1.3150 INCH. Use caliper set.
(8) Check spline teeth.
(a) No scuffing, scoring, or spalling allowed.
(b) Maximum pitting depth before blending 0.008 INCH. Use depth gage.
(c) Maximum wear step 0.008 INCH. Use depth gage.
(d) Measure “Over Balls” diameter with two 0.1920 INCH diameter gage balls placed in tooth spaces
approximately 180 degrees apart. Take three “Over Balls” measurements at locations approximately
120 degrees apart. Minimum “Over Balls” diameter 1.7794 INCH. Use caliper set.
(9) Check five 0.2500 INCH hole diameters. Maximum diameter 0.2585 INCH. Use caliper set.
(10) Check cadmium plating. Damaged and missing cadmium plating is acceptable.
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