MIL-PRF-32516
APPENDIX A
VIBRATION STIMULATION
A.1 SCOPE
A.1.1 Scope. This appendix details ways to isolate failures related to vibration. This
appendix is not a mandatory part of the specification. The information contained herein is for
guidance only.
A.2 DETERMINING CAUSES OF INTERMITTENT FAILURES
A.2.1 Introduction. Each LRU/WRA is different in its function and operational
environment. As a result, no single test method or procedure can adequately replicate an
intermittent fault occurrence for all LRUs/WRAs. A careful review of the nature of the failure
and the operational conditions under which the failure occurred is required. The following steps
are recommended when by careful analysis it is determined that the failures occur during ground
or flight operating conditions, and the operating temperature does not appear to be contributing
to the occurrence of the failures.
A.2.2 Typical resulting effects. The following is a list of typical resulting effects of
vibration-induced problems (this list is not intended to be all-inclusive):
a. Chafed wiring.
b. Loose fasteners/components
c. Intermittent electrical contacts
d. Electrical shorts.
e. Deformed seals.
f. Failed components.
g. Optical or mechanical misalignment.
h. Cracked and/or broken structures.
i. Migration of particles and failed components.
j. Particles and failed components lodged in circuitry or mechanisms.
k. Excessive electrical noise.
l. Fretting corrosion in bearings.
A.2.3 Operational vibration environment. A review should be conducted of technical
manuals, operating manuals and any available information which provides insight into the
operational vibration environment of the LRU/WRA. As much as practical this information
should be used to tailor a vibration envelope for vibrating the LRU/WRA while troubleshooting
the LRU/WRA for intermittent faults. It is not necessary to vibrate the LRU/WRA at full
qualification levels which may induce additional failure modes. It is recommended that where
the operational are not known, the qualification vibration test levels may be reduced by a factor
of eight and used during troubleshooting of the LRU/WRA. The intent is to subject the
LRU/WRA to a vibration level high enough to stimulate the intermittent fault, but not reduce the
operational life of the LRU/WRA.
A.2.3.1 Unknown operational limits. Where the vibration operational limits are
unknown, MIL-STD-810, Test Method 514 should be used to tailor the LRU/WRA vibration
stimulation test sequence as a function of the life cycle environments of the LRU/WRA:
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