SRC Forum - Message Replies


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

Back to message list Topics List About this forum
Original Message:

Posted by: Sheila Prather (sheila_s_prather@mail.northgrum.com )
Organization:Northrop Grumman Corporation
Date posted: Wed Sep 20 14:25:14 US/Eastern 2000
Subject: Operational Parameter Translation - Question #2
Message:
This is a followup to my question posted on 9/11/00 regarding the TR-89-299. I've noted the caution that should be exercised when using this document...this question addresses the examples that are published in the "Reliability Toolkit: Commercial Practices Edition". I see where example #1 has been corrected from the previous 4/93 version of the toolkit; but, my question rests with example #2. Looking at Section 5.4.1.1 of TR-89-299, in example #2 why was the field number for flight hour determination based on 1,672 hours versus 1,000 hours (50% of 2,000)?


Reply:

Subject: Operational Parameter Translation
Reply Posted by: Bruce Dudley (bdudley@alionscience.com )
Organization: Reliability Analysis Center
Date Posted: Wed Sep 20 14:59:37 US/Eastern 2000
Message:
The example #2, as shown in the Reliability Toolkit; Commercial Practices Edition, is in error. Your comment is correct, the default value should be used for this approximation. Therefore, the MTBF(f) is equal to 2000/2 which equals 1000 hours between failure not the 1,672 shown. If flight hours are considered, the number is 1000/1.2 which equals 833.3 flight hours between failure. If the toolkit is ever updated this correction will be entered.


Back to message list Topics List About this forum
Reply to this message