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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: John S. Hoegbraathen ( )
Organization:Kongsberg Defence & Aerospace
Date posted: Wed Jul 14 7:00:11 US/Eastern 1999
Subject: Dudding of EEDīs
I am a system safety/reliability engineer working in an AEROSPACE company. I am looking into the possibility of including a bridgewire conductivity test for some of the EEDīs (Electro Explosive Device) in a new system which is currently under development. This test will perhaps be a part of a built in test. The proposed test current is 1 - 2 mA over a 10 to 100 msec interval. The EED tested will all be of 1A/1W type (hot bridgewire devices), pr MIL-I-23659C. Could this testing lead to dudding (fails to operate when called upon) of the EEDīs if the test is frequently used? What are the test limitations concerning the possibility of dudding? Are there anyone who could answer these questions or direct me to relevant l


Subject: EEd's Testing
Reply Posted by: Bruce Dudley ( )
Organization: Reliability Analysis Center
Date Posted: Mon Jul 19 15:41:19 US/Eastern 1999
We at the Reliability Analysis Center have recently completed a test plan for Electro Explosive Devices (EED) for long term storage. Accelerated testing was performed by the customer with periodic "bridgewire" resistance and insulation resistance testing. This accelerated storage testing was performed at high temperature (90 degrees C and 90% RH) with periodic resistance measurments every 400 hours to the finish at 2000+ hours. No sign of change in resistance was observed with this test and all 40 devices were exploded successfully. From this, one could say that careful testing has no adverse effect. At the other extreme, RADC-TR-89-274 "Dormant Missile Test Effectiveness" report indicates that testing induces more failures than the units experience during storage. The overall conclusion in this report is, less testing is better.

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