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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: Quynh Nguyen ( )
Organization:SR Telecom, Inc.
Date posted: Tue Apr 4 11:15:17 US/Eastern 2000
Subject: MTBF calculation using Bellcore TR-332
I am a Component Engineer at SR Telecom and will perform the reliability for component and board level for communication product using Bellcore TR-NWT-000332. I can calculate the total device failure rate (lamda) but get stuck with the MTBF formula. I need to sort out all the formula so can write the VB software for MTBF calculation interface with our current MRP database. Please email me if you know the MTBF formula.
Thanks in advance, Quynh Nguyen SRT Comp. Eng.


Subject: MTBF calculation using Bellcore TR-332
Reply Posted by: Jack Farrell ( )
Organization: Reliability Analysis Center
Date Posted: Tue Apr 4 13:23:16 US/Eastern 2000
The formula for converting failure rate to MTBF is found in Mil-Hdbk-338 (Section 5 Page 5-7). The MTBF for an item is equal to 1 divided by the items failure rate, given a constant failure rate and replacement upon failure. Since Bellcore expresses failure rate in FITS (failures per billion hours) your VB equation would look like this: MTBF = 1000000000/X where X is your Bellcore failure rate in FITS

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