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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: Julien NICO (jnico@zodiac.com )
Organization:Zodiac
Date posted: Thu Feb 13 4:11:02 US/Eastern 2003
Subject: Overhaul
Message:
We are developping a system for aircraft made of several component (electronic,mechanic, pneumatic). One of this component (an air compressor) has an ovberhaul period. To build my system MTBF, shall i use the overhaul period or the MTBF (what can be the mtbf of an overhaul component?). If i have to use the MTBF, what is the interest of the overhaul, beacause it is sensed to extend the life of the component.


Reply:

Subject: Overhaul Reliability
Reply Posted by: BWD (bdudley@alionscience.com )
Organization: RAC
Date Posted: Tue Feb 18 13:59:47 US/Eastern 2003
Message:
When one computes the mean time between failure [MTBF] for a given product, we use the chance or defect failure rates that have been accumulated from past experience. This failure rate, if exponentially distributed, can then be added to other like distributions to obtain a unit estimation of the reliability. The overhaul is not included in this estimation process. The overhaul is the process used to re-new the product by eliminating any "wear-out" failure modes. So, if the overhaul is successful, the product should be returned to service as a like new item. At this time, the chance failures are again the defining element in the reliability estimation process. If the overhaul is not performed, then end of life failure information has to be included in the reliability estimation process. Weibull distributions are often used with the wear-out consideration. The Reliability Toolkit; Commercial Practices Edition addresses failure distributions, failure rates and other important reliability information. All reliability practitioners should have a copy.


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