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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum (src_forum@alionscience.com )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Original Message:

Posted by: Sheila Prather (sheila_s_prather@mail.northgrum.com )
Organization:Northrop Grumman Corp
Date posted: Fri Oct 26 12:54:29 US/Eastern 2001
Subject: MIL-HDBK-344A - ESS for Electronic Equipment
Message:
Mil-hdbk-344A references parametric vs. functional testing? What are the differences in the two?


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Subject: Parametric Testing
Reply Posted by: B.W.Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Thu Nov 8 14:39:28 US/Eastern 2001
Message:
Referencing Mr. Mahoney's question on over testing of units, my response is that any testing uses part of the useful life of the item. Testing at overstressed conditions causes loss of life at an accelerated rate. If one consults the equations in MIL-HDBK-344 ESS Testing, you will find some useful information on calculating how much of the life is expended by an accelerated test for temperature cycling or vibration testing. With regard to placing the equipment back in the "field", I recommend that an overhaul be considered for all qualification level tests units and overstressed ones that exceed the normal design limits.


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