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: Daniel Mahoney
Date posted: Fri Feb 4 10:19:48 US/Eastern 2000
Subject: Mechanical dormant failure rates
Can anyone shed some insight into the dormant failure rate ratio one should use for mechanical components.
The various handbooks suggest numbers of 1 to 10 through 1 to 100 for electronic components, but I would think that mechanical components would be much higher.
Subject: Mechanical Dormant Failure
Reply Posted by: Bruce Dudley
Organization: Reliability Analysis Center
Date Posted: Mon Feb 7 9:57:05 US/Eastern 2000
Some mechanical part failure rates for dormant conditions are included in the RAC Non-Electronic Parts Reliability Data - 95 handbook. The Naval Surface Warfare Center, Carderock Division has published a mechanical reliability prediction handbook that has some failure conditions, such as corrosion, contamination or lubrication, that could be translated to dormant conditions. Your basic question, regarding the fact that electronic "rules of thumb" for operating to dormant failure rates seem to be better than mechanical, revolves around the corrosion and contamination failure mechanisms. Mechanical parts seem to have less protection, more exposed surface area and the corrosion or contamination starts wear points on the unit when operated after storage. As a result, the dormant failure rates for mechanical parts are more significant than the electronic. From personal experience, whenever I store the "winter rat auto", I usually experience brake problems the following fall due to corrosion and fluid contamination. The electronic components never have any problems.