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

Original Message:

Posted by: JM Cloarec (jmcloarec@thsrc.com.tw )
Organization:IREG
Date posted: Tue Oct 28 22:57:59 US/Eastern 2003
Subject: MTBF assignment
Message:
Can we estimate a MTBF target like that : reliability performance system is any failure should occur less than once per year. As the system is used 18h per day, the MTBF must be equal or greater to 6,570 h i.e (8,760 / 24) * 18.

Previous reply

Reply:

Subject: Confidence
Reply Posted by: BWD (bdudley@alionscience.com )
Organization: RAC
Date Posted: Wed Nov 5 8:57:20 US/Eastern 2003
Message:
In the chi-square equation and the table, alpha is the risk factor and is 1 - the confidence level. So, a 90% confidence is a 10% risk factor which you use in the table to obtain a estimate for the one sided lower level MTBF. This answers the question of what value you need to meet the required reliability at 90% confidence.