MIL-DTL-45913D
4. VERIFICATION
4.1 Classification of inspections. Inspections shall be classified as quality conformance inspection
(see 4.2).
4.1.1 Inspection lot. All locknuts of the same type, material, protective finish, thread series, and size
produced under essentially the same conditions and offered for acceptance at one time shall be considered a lot for
the inspection purposes.
4.2 Quality conformance inspection.
4.2.1 Sampling. Sampling for conformance inspection shall be in accordance with ASME B18.18.2M
unless otherwise specified.
4.3.3 Proof load and prevailing torque testing (steel nuts).
4.3.3.1 Carbon and alloy steel locknuts shall be subjected to the proof loads and prevailing torque specified
in SAE J995 or TABLE 1 of this specification.
4.3.3.2 CRES locknuts shall be subjected to the proof loads and prevailing torque specified in ASTM F594.
4.3.4 Protective finish test. Nuts shall be tested in accordance with the applicable protective finish or
plating specification . Each lot shall be tested for protective finish thickness and, when specified, salt spray
testing.
4.3.5 Hardness test. When a hardness test is to be conducted in lieu of a proof load test, it shall be
conducted in accordance with NASM1312-6. Hardness tests may not be substituted for proof tests on nuts that
require a proof load over 120,000 pounds.
4.3.6 Magnetic permeability. Magnetic permeability shall be determined by the use of an indicator in
accordance with ASTM A342. Magnetic permeability sampling shall be in accordance with ASTM F1470.
4.3.7. Discontinuities. The acceptance of locknuts shall in accordance with the requirements contained in
sampling for discontinuities, ASTM F812.
4.4 Test Methods.
4.4.1 Proof load test. Steel locknuts shall be tested in accordance with ASTM F606. Proof load values shall
be per Table 1 or SAE 995or ASTM F594.
4.4.2 Prevailing torque test. Steel locknuts shall be subjected to the prevailing torque test as specified in
National Aerospace Standard specification NASM25027.
4.4.3 Test equipment . A hardened threaded mandrel or bolt shall be used in conjunction with a tension
testing machine for conducting the proof load test. The mandrel or bolt shall be threaded to the unified thread
series and class of the locknut being tested. The mandrel or bolt shall have sufficient strength to ensure failure of
the locknut.
4.4.4 Test Procedures. Locknuts shall be assembled and mounted in a tension testing machine and
subjected to a load equal to the proof load specified in SAE J995 or TABLE 1. To meet the requirements of this
test, the locknut shall resist the load without stripping or rupture.
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