MTBUR = Mean Time Before Unscheduled Removal and MTBF = Mean Time Before Failure. Statistical terms that have distinct and very precise definitions in reliability engineering.
Lu is very detailed in analysing the meaning of the terms, but I preferred not to confuse the issue by going into detailed statistical analysis. The MTBUR came from reliability data circulated among us Technical Services people. Put simply, the MTBUR hours and cycles figures given suggest that the B757/RB211-535E4 starters do not have a fleet reliablity problem.
spannersatcx said it more succinctly in four words. Skytrucker87's company may have an in-house problem.
**********************************
Through difficulties to the cinema
[This message has been edited by Blacksheep (edited 20 October 2000).]