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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: Laurent Purrey (LPurrey@zodiac-group.com )
Organization:AERAZUR-ZODIAC GROUP
Date posted: Tue May 2 2:25:38 US/Eastern 2000
Subject: MTBF & Failure Modes
Message:
I'm working on a FMECA and I have a problem to find some reliability data on a component: a fire protection. This fire protection overlaps a rubber part and protect it against oil leakage coming from a turbopropeller engine. In fact, the fire protection is a specific foam which is expandable with the heat. I don't find an equivalence within the NPRD-95 and FMD-97 respectively for the MTBF value and the associated Failure Modes. It would be helpful if you could give some sources or data regarding this application. Thank you for your help.


Reply:

Subject: Fire Protection Device
Reply Posted by: Jack Farrell (jfarrell@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Thu May 4 14:52:17 US/Eastern 2000
Message:
You are correct in finding no information in NPRD-95 or FMD-97 for your anti-fire coating. I am going to assume that this coating is a one-shot type device and that it is not repairable. I would also assume that the operation of this device is a chemical reaction occurring within the device that is triggered by elevated temperature. Based on these assumptions, I suggest that you focus on the expected life of this device with reference to the use environment rather than on failure modes and MTBF. The first place to start would be with the manufacturer of this coating. They should have information on the expected life of this material. You need to consider all aspects of your use environment and their potential for shortening the material life. The Arrhenius equation may be of value in this analysis if an activation energy is available for the device material. When you arrive at the expected life of your device I would consider this number to be the Mean Time To Failure (MTTF) rather than the MTBF.


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