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: Sheila Prather
Organization:Northrop Grumman Corporation
Date posted: Wed Feb 27 10:33:58 US/Eastern 2002
Subject: ESS Screening Strength Assessment - Mil-Hdbk-344A
I've used Mil-Hdbk-344A to calculate the screening strength at different levels of assembly, e.g., SRU and LRU levels for the system under evaluation. I now want to compute the overall system level screening strength given the lower level results. Any recommendations as to how the two sets of data should be combined?
Subject: ESS Mil-HDBK-344a
Reply Posted by: Edward Sherwin
Date Posted: Thu Feb 28 10:48:51 US/Eastern 2002
Section 5 in MIL-HDBK-344A describes the proper procedure for determining the screen strength of a system. One cannot combine individually calculated screen strengths to determine the system screen strength. Figure 5-2 show how the relationship of the various component of the system must be addressed.
Note that two pieces of information are required to calculate the screening affect on the total system, the number of incoming defects of each component in the system and the number of defects that are being induced by each manufacturing step. MIL-HDBK-344A contains the methodology for determining incming defects.