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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: Steve
Date posted: Thu May 10 10:05:49 US/Eastern 2001
Subject: Calculated Failure Rate vs. Field Failure Rate
Message:
Hello, I performed a reliability prediction based on TR-332, and the failure rate looks high. We believe that the real failure rate should be better. Since the product is brand-new, no field data available yet. Is there a ratio of calculated failure rate to field one? Or are there any references addressed this issue? BTW, the product is a telecomunication switch used in central office. Thanks in advance! Steve


Reply:

Subject: Calculated Failure Rate vs. Field Failure Rate
Reply Posted by: Gary Sunada (gsunada@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Fri May 11 10:47:20 US/Eastern 2001
Message:
Hello Ė Theoretically, performing a prediction using TR-332 (also known as Telecordia GR-332) should give you failure rates that approximate your future field data, so no factor adjustment should be necessary. However, this is dependent on a fairly large assumption: is the model based on current, accurate data? If you believe that there are unique circumstances that may not apply itself to the TR-332 model, you may prefer an alternative, such as RACís PRISM software, which is based on MIL-HDBK-217.


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