Forum: Reliability & Maintainability Questions and Answers
Posted by: Clay Davis Date posted: Tue Aug 15 2:50:17 US/Eastern 2000 Subject: MTBF Calculations (Customer Complaint) Message: Several of our computers have an MTBF of 50,000 hrs. However, a major customer states that if they purchase 100 systems 9 will fail in the first 6 months and another 9 will fail by the end of the first year. Agreed this is numerically accurate (1/(50,000*365*24*100)) - however this does not seem right. I tried to explain that not every failure will cause a system failure (ie a capacitor) but they did not agree without us being able to prove these parts are truly redundant (which they are probably not). Thoughts? There has to be something that I am missing. Thank you for your help. --Clay
Posted by: Dominique Roy (doroy@transport.bombardier.com ) Organization:Bombardier Date posted: Mon Aug 14 13:24:34 US/Eastern 2000 Subject: Environment factor conversion for NPRD-95 Message: Some of our suppliers have to provide reliability calculations for mechanical parts. Our spec. is calling the use of NPRD-95, Gm environment for mechanical parts reliability predictions. Some of the parts failure rates found are available only in a Gf ou Gb environment. Are there conversion factors that can be applied to the base failure rate to reflect the Gm environment for mechanical parts? Needed: From Gb, Gf, N, Ai, Au, ARW, CL to Gm. Thanks!
Posted by: KEITH WALKER (KEITH.WALKER@THAAD.ARMY.MIL ) Organization:US ARMY Date posted: Thu Aug 10 22:58:15 US/Eastern 2000 Subject: QUALITY fACTORS AND BELLCORE RELIABILITY PREDICTIONS Message: DOES ANYONE KNOW OF ANY SELECTION GUIDELINES FOR THE QUALITY FACTOR IN BELLCORE? I AM SPECIFICALLY INTERESTED IN THE PREDICTION OF MILITARY EQUIPMENT RELIABILITY WHEN COMMERCIAL PARTS ARE USED. ANY TECHNICAL JOURNAL REFERENCES WOULD BE MOST APPRECIATED. THANKS KEITH WALKER
Posted by: Bob Valerius (robert_m_valerius@md.northgrum.com ) Organization:Northrop-Grumman Oceanic & Naval Systems Date posted: Wed Aug 9 8:45:07 US/Eastern 2000 Subject: ESS Message: Hi I am wondering what the current thinking on ESS is. It appears to me that activity in this arena is waning as most screening is no longer viewed as needed, especially with so many COTS products. Is this an accurate view? Comments and emails from those with experience would be appreciated.
Posted by: Thomas D'Eufemia (deufemia@teas.eglin.af.ml ) Organization:Sverdrup TEAS Date posted: Mon Aug 7 15:15:22 US/Eastern 2000 Subject: R and M data collection Message: Does anyone have a nice neat format for R$M data collection
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