SRC Forum - Message Replies
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
Posted by: Luke DENG
Organization:Aerospace Development Center
Date posted: Sun May 6 23:32:18 US/Eastern 2001
Subject: What's the definition of 4 Reliability parmameters ?
What's the following 4 parameter meaning ?
1.Mean Time Between Downing Event
2.Mission Time Between Critical Failure.
3.Mean Time Between Maintenance.
4.Mwan Time Between Demand
Subject: Reliability Definitions
Reply Posted by: Bruce Dudley
Organization: Reliability Analysis Center
Date Posted: Tue May 8 11:46:49 US/Eastern 2001
The definitions for the reliability terms that you have indicated are defined in MIL-HDBK-338, Military Handbook, Electronic Reliability Design. The definitions are:
MEAN TIME BETWEEN DEMAND (MTBD): A measure of system reliability related to demand for logistic support. The total number of system life units divided by the total number of system demands on the supply system during a stated period of time.
MEAN TIME BETWEEN DOWNING EVENTS: A measure of system reliability related to readiness and availability. The total number of system life units divided by the total number of events which cause the system to be unavailable to initiate its mission(s), over a stated period of time.
MEAN TIME BETWEEN CRITICAL FAILURE (MTBCF): A measure of mission or functional reliability. The mean number of life units during which the item performs its mission or function within specified limits, during a particular measurement interval under stated conditions.
MEAN TIME BETWEEN MAINTENANCE (MTBM): A measure of the reliability taking into account maintenance policy. The total number of life units expended by a given time, divided by the total number of maintenance events (scheduled and unscheduled) due to that item.