MIL-DTL-68G
Table III. Sampling for group B tests.
Production
Number of fans to be
lot size
selected for group B tests
90 and under
1
91 to 500
2
501 to 1200
3
1201 to 3500
4
3501 and over
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4.4
Conformance inspection.
4.4.1 Group A examination and tests. The sample fans, selected in accordance with 4.3.2, shall be subjected
to the examination and tests specified in table IV. Failure to conform to the specification requirements for any
group A examination or test shall be counted as a defect, and the lot represented by the sample shall be rejected.
Table IV. Group A examination and tests.
Requirement
Test
Group A
Paragraph
Paragraph
Visual examination
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4.5
Insulation resistance (cold)
3.20.1
4.6.1.1
Speed
3.12 and 3.15
4.6.2
Power input
3.8 and 3.11
4.6.3
Dielectric strength
3.19
4.6.4
4.4.2 Group B tests. The sample fans, selected in accordance with 4.3.3, shall be subjected to the tests
specified in table V. In the event of failure to conform to the specification requirements for the group B tests the
supplier shall correct the cause of failure on future production units and repair the deficiency in any fans not yet
shipped. After all fans in the production lot have been repaired, the production lot shall be subjected to those tests
specified in table V on which failures occurred. None of the fans of the production lot previously tested shall be
retested.
4.5 Visual examination. The fan shall be subjected to a visual examination to ascertain that the structural
details and character of workmanship conform to this specification. The fan shall also be checked against the
accepted drawing.
4.6
Test procedures.
Insulation resistance.
4.6.1
Table V. Group B tests.
Requirement
Test
Group B
paragraph
paragraph
Output
3.8 and 3.13
4.6.6
Operation for 4 hours to cause heating
--
4.6.7
Airborne noise
3.10
4.6.8.2
Insulation resistance (hot)
3.20.2
4.6.1.2
Operation for 100 hours
--
4.6.9
Permeability
3.2.2
4.6.13
4.6.1.1
Cold. The insulation resistance of the fan shall be measured to determine compliance with 3.20.1.
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