MIL-PRF-49176B(CR)
4.6.3 Low temperature. Measure compliance with the requirement 3.6.3. Recommend
performing the tests prescribed in 6.4. Failure to meet the requirement shall constitute failure of
the sample.
4.6.4 Shock. Measure compliance with the requirement of 3.6.4. Recommend performing
the tests prescribed in 6.4. Failure to meet the requirement shall constitute failure of the sample.
4.6.5 Vibration. Measure compliance with the requirement of 3.6.5. Recommend
performing the tests prescribed in 6.4. Failure to meet the requirement shall constitute failure of
the sample.
4.7 Reliability.
4.7.1 First article reliability. The lower test MTBF (θ1 ) shall be demonstrated in accordance
with the following subparagraphs:
4.7.1.1 Inspection level.
· Temperature: +50°C, (+5 -0)°C
· Temperature cycle: None
· Vibration: 2.2 g's, ±10 percent peak acceleration value at any nonresonant
frequency between 20 and 60 Hz measured at the mounting points of the
equipment. The duration of vibration shall be at least 10 minutes during each
hour of equipment operating time. The vibration shall be perpendicular to the
plane of the printed circuit board.
· Equipment on-off cycling: Turn on and let temperature stabilize, hold for 3
hours, then turn off and let temperature stabilize. This cycle shall continue
throughout this requirement verification.
4.7.1.2 Parameters. The discrimination ratio θ0/θ1 shall be 3.
4.7.1.3 Failure criteria and inspection length. The inspections of Table III shall be
performed at least once prior to and once after the inspection of 4.2.3.1. Additional inspection of
Table III may be selected by the contractor. The results of all Table III inspections and any
physical damage shall be used to determine the success or failure of the reliability requirement. In
the event of a Table III inspection failure, the time interval between the preceding successful
inspections and the failure shall not contribute to the total cumulative hours. Verification shall
continue until the total unit hours together with the total count of relevant equipment failures
permit either an accept or reject decision in accordance with Figure 5. Only equipment "on" time
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