PRISM Forum - Message Replies

Topic: PRISM Questions and Answers
Topic Posted by: SRC ( )
Organization: SRC
Date Posted: Wed Jan 12 8:33:33 US/Eastern 2000
Topic Description: Welcome to the PRISM forum! Please feel free to post your questions and comments about the PRISM assessment software here.

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Original Message:

Posted by: Dave Ellis ( )
Organization:Ellis Quality Engineering Services
Date posted: Tue Oct 10 11:50:29 US/Eastern 2000
Subject: System/Assembly level failure rate roll ups
I am in the process of generating a medium sized prediction and have noticed that the system or assembly level failure rate summarizations don't agree with manually calculating the total failure rates. For example, one assembly has 2.379, another 0.094 and another 0.065, but the overall system failure rate is only at 0.589 and the system level hardware component is less than the total sum. Comments? Thanks.

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Subject: System/assembly level FR roll ups
Reply Posted by: Dave Ellis ( )
Organization: Dave Ellis
Date Posted: Tue Oct 10 14:03:15 US/Eastern 2000
I just purchased PRISM 1.0 last week and downloaded the most recent update - 1.1 over the weekend. I am confused then as to what my results are. I understand there is process grade modifier, but to go from about 4.00 in overall failure rate for all components summed, to <1.0 at the system level does not seem correct. Plus, depending on the report I generate, I get different FRs. I am using Ground Stationary, with a commercial aircraft operational profile. Also, I noticed there are no RACRates for inductors? When will these be added? I am using either Bellcore or 217 in the mean time. Thanks.

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