MIL-DTL-21248C
4. VERIFICATION
4.1 Responsibility for inspection. Unless otherwise specified in the contract or purchase
order, the supplier is responsible for the performance of all inspection requirements as specified
herein. Except as otherwise specified in the contract or order, the supplier may use his own or
any other facilities suitable for the performance of the inspection requirements specified herein,
unless disapproved by the Government. The Government reserves the right to perform any of the
inspections set forth in the specification where such inspections are deemed necessary to assure
supplies and services conform to prescribed requirements.
4.2 Sampling.
4.2.1 Lot. A lot shall consist of all the retaining rings of the same type, class, size, material
and finish, manufactured under essentially the same conditions and presented for examination
and inspection.
4.2.2 For quality conformance examination. Sample retaining rings, packages and shipping
containers shall be selected from each lot in accordance with ASQ Z1.4 Inspection Level II for
examination in accordance with 4.3.1.
4.2.3 For quality conformance tests. Sample retaining rings shall be selected from each lot in
accordance with ASQ Z1.4, Inspection Level S-3 for testing in accordance with 4.3.2. If the lot
consists of less than 26 rings, 10 percent of the lot shall be selected at random for testing.
4.3 Inspection.
4.3.1 Examination.
4.3.1.1 Quality conformance examination. Sample retaining rings selected in accordance
with 4.2.2 shall be visually and dimensionally examined to verify compliance with the
requirements of the contract or order and this specification. The rings shall be accepted or
rejected in accordance with the requirements of ASQ Z1.4.
4.3.2 Tests.
4.3.2.1 Quality conformance tests. Sample retaining rings selected in accordance with 4.2.3
shall be tested as specified in 4.3.2.1.1 and 4.3.2.1.2 in accordance with the requirements of
ASQ Z1.4. Any retaining ring containing one or more defects shall be rejected. If the quantity of
defective rings in the sample exceeds the acceptance quantity for that sample, the lot
represented shall be rejected.
4.3.2.1.1 Performance and crack tests. Prior to the hardness test of 4.3.2.1.2 the sample
retaining rings selected in accordance with 4.2.3 shall be subjected to the tests of 4.3.2.1.1.1
through 4.3.2.1.1.5 as applicable.
4.3.2.1.1.1 Class 1 retaining rings (all types). Class 1 rings (all types) shall be compressed
so that the open ends of the ring touch but do not overlap. After compressing and releasing the
ring 5 times, the ring shall be visually and dimensionally inspected for compliance with the
requirements of 3.5.4.6.1.
4.3.2.1.1.2 Type I, Classes 2, 4 and 10; Type II, Class 2; and Type III, Class 2 retaining rings.
Type I, Classes 2, 4 and 10; Type II, Class 2; and Type III, Class 2 retaining rings shall be
expanded over and removed from a shaft 1 percent larger in diameter than the nominal size shaft
for which the rings are intended. After repeating this test 5 times the free diameter of the rings
shall be checked for compliance with the permanent set limitations specified in 3.5.4.6.2. Each
sample ring shall then be expanded over a shaft 15 percent larger in diameter than the applicable
free ring diameter. After this test the rings shall be inspected for conformance to the cracking
requirements of 3.5.4.6.2.
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