Evaluation of Environmental Profiles for Reliability Demonstration
Final technical rept. Jun 1973-Jan 1975
GRUMMAN AEROSPACE CORP BETHPAGE NY
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This report describes the results of a 19-month study to determine the adequacy of the environmental profiles of MIL-STD-781, Reliability Tests Exponential Distribution, and provide recommendations for their improvement. The environmental and failure history of a sample of 95 avionic weapons replaceable assemblies WRAs served as the vehicle for this evaluation. Environmental data during demonstration testing and actual field exposure for each WRA was collected, analyzed, and compared. Test failure history and field failure experience were reviewed and reliability measures for each determined. Comparisons of lab-field reliability differences with environmental differences indicated that insufficient thermal cycling inadequate vibration testing in terms of level, duration and frequency and lack of moisture exposures were deficiencies in the current environmental profiles. Recommended profiles which would eliminate these weaknesses are presented. In addition, the need for consistent ground rules, failure scoring criteria, and a strong end-item burn-in test are described.
- Test Facilities, Equipment and Methods