(f)
Electroetch an asterisk adjacent to bearing part number. One asterisk represents one overhaul inspection cycle. For example: *** etched adjacent to part number indicates three overhaul inspection cycles (time in service periods for each use). Bearings shall be discarded when cycle limits have been reached. (Refer to cycle limits specified in applicable manual.)
NOTE: Bearings that are used in pneumatic valves do not require a coating of oil, as bearings are installed dry.
(g)
Dip bearing in oil (MIL-L-6085) (SECTION VII) heated to 120 to 140F (49 to 60C) for five minutes and allow to drain.
(h)
Package bearing along with part number identification in heat sealable transparent plastic bag (MIL-B-22191D) (SECTION VII), evacuate air from bag and heat seal shut.
F. Gear and Spline Inspection
(1) Check gear and spline teeth as follows:
(a)
Perform visual check using a strong light and a minimum of 5 times magnification. See Figure 319 and Table 306 for typical examples of gear and spline wear.
(b)
Visually check part for evidence of excessive spalling, fretting, surface flaking, chipping, splitting, rubbing, chafing, corrosion or other defects per Figure 319 and Table 306. If any of the defects specified are evident, replace part.
(c)
Visually check part for evidence of excessive corner loading. If wear pattern indicates corner loading of less than three-fourths of the normal length of tooth bearing contact area, replace part.
(d)
Visually check part for evidence of metal displacement. If metal displacement is to the extent that sub-surface damage is probable, replace part.
NOTE: Healed scuffing of tooth involute surfaces is evidenced by a matted gray finish or localized burnished appearance, which usually results from wearing off raised metal. This condition is acceptable provided the scuffed area does not exceed 30 percent of the indicated pattern width, and the involute contour visually appears unaltered and no spalling or fretting exists.
(e)
Visually check part for evidence of healed scuffing of tooth involute surface.
Inspection
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(f)
Check parts for cracks by performing magnetic particle inspection (SECTION III). No cracks are permissible.
(g)
Visually check part for evidence of overheating discoloration. If overheating discoloration of metal is evident, replace part, unless otherwise noted in applicable manual containing inspection criteria for the part.
(h)
Visually check teeth for evidence of abnormal or deep wear patterns. If visual check reveals abnormal or deep wear patterns, dimensionally check part by measuring gear teeth, over or between, pins or balls, placed in wear area, in accordance with applicable manual, containing inspection criteria for the part.
(i)
If overheating discoloration is evident, check gear hardness as specified in applicable manual to determine if gear is acceptable for further use.
(j)
Refer to applicable manual for wear limits of splines.
Typical Spline Wear Patterns and Locations
Figure 319
Inspection
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Table 306. Gear and Spline Teeth Physical Conditions
Term
Broken
Chipped
Cracked
Frosted
Pitted
Scored
Definition
Missing piece or pieces of a part.
Missing piece or pieces of a part.
A partial failure
Appearance of micropitting. Normal wear pattern appears frosted; the normal polish of surface has an etch-like finish: under magnification, the surface appears to be a field of very fine micro-pits less than 0.0001 in (0,00254 mm) deep.
Surface fatigue characterized by small pits of 0.015 in (0.381 mm) deep.
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