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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

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

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Original Message:

Posted by: Elizabeth M. Chappel ( )
Organization:Belcan Engineering
Date posted: Tue May 11 16:31:55 US/Eastern 1999
Subject: FMEA (CA) Definitions and Guidelines
I am establishing the guidelines and the definitions for severity (criticality), failure mode probability and detection for a System Level FMEA. The product has an aerospace application in which it is active at all times. Some vendors will be providing data (failure rates) for electronic components, while others may find it easier to provide probabilities of occurrences. However, there's the rub, how to define and correlate the two and make sense. I need to provide def'ns that make sense. The present military definition for Qualitative Probability isn't helpful, nor is the automotive. Help. What type of scale do you suggest for a product that is always active? (I have completed the Severity (Criticality) Definition, Detection won't be a problem, it's just this probability). The various sources I've viewed don't clarify it any. (old Mil-Std-1629, SAE-ARP-5580 advanced review copy). Thanks Beth

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Subject: Bruce's Reply
Reply Posted by: Elizabeth M. Chappel
Date Posted: Mon Jun 21 11:18:25 US/Eastern 1999
Thanks for the reply. And wouldn't you know it, just after I wrote this message, I received the AC 25.1309-1A. I had ordered it the week before and with it in hand I set up the probability levels. As for the always active, well, that is still a question, since the battery life may be the active life. Again, still working the issue. Thanks again. Beth

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