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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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Posted by: Wu Xiangping ( )
Date posted: Tue Aug 3 22:44:36 US/Eastern 1999
Subject: Reliability Prediction
We all know that the result of reliability prodiction is much higher than the true reliability level.Does anyone know the proportion between them? Another problem is,a new product,has no reliability requirement from customer,how to decide the reliability requirement that the product should achieve? Thanks very much.

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Subject: Reliability Prediction
Reply Posted by: Bruce Dudley ( )
Organization: Reliability Analysis Center
Date Posted: Thu Aug 19 9:18:02 US/Eastern 1999
Not all reliability predictions are much higher than the fielded reliability. In the cases where one is using the older prediction methods that have heavy commercial part quality penalaties and are used in low stress situations, fielded reliability are often greater than predicted. A 1989 study (RADC-TR-89-299 Reliability and Maintainability Operational Parameters Translation) performed by IITRI for the Air Force, developed parameters for translation of predicted values to fielded ones. In general, the ratios are: 0.9 for ground fixed environment, 0.3 for ground mobile environment and 0.4 for aircraft. Specific parameters for equipment types and prediction methods are included in this study.

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