Forum: Reliability & Maintainability Questions and Answers
Posted by: Richard Smith
Date posted: Wed Nov 20 13:59:39 US/Eastern 2002
Subject: Looking for MIL-STD-882A System Safety Document
If anybody know of a location for MIL-STD-882A on the web, could they please provide a link. I have rev's B,C and D, but need to refer to 'A' for a specific program.
Thanks in advance.
Posted by: Xavier
Date posted: Mon Nov 18 17:31:16 US/Eastern 2002
Subject: Silicon Reliability Certifications?
Does anyone know of any silicon reliability certifications? Specifically, I have successfully achieved the Certified Reliability Engr from ASQ but would like to gain some more technical knowledge in the Si reliability arena.
Thank you for your help.
Posted by: Michelle Li
Date posted: Fri Nov 15 14:53:07 US/Eastern 2002
Subject: possible missleading of 217 on chip ceramic capacitors
I am working on reliability prediction for a commercial avionics flight display. I found that surface mount ceramic capacitor failure rate is about 35% of total failure rate of all elelctronic assemblies ( exclude LCD assembly and lamp assembly) by using 217. I actually did not choose 'Chip Ceramic' subcatogory, I chose 'general purpose, ceramic capacitors'. If I used 'chip, ceramic', the total failure rate of chip ceramic capacitor will go to 50%.
If I just use PRISM for surface mount ceramic capacitors and still use 217 for other parts, the ratio will drop to 5%. Can someone tell me if surface mount ceramic capacitors cause about 35% of failures in field? It is hard for me to believe so. I guess that they might cause 1% to 5% of failures in field. If someone works on commercial avionics field reliability, I would appreciate if you can give some information about field performance of the surface mount ceramic capacitors. Thank you very much. Michelle Li
Posted by: Michelle LI (Michelle.firstname.lastname@example.org )
Date posted: Fri Nov 15 8:38:55 US/Eastern 2002
Subject: Functional FMEA
I have a question about functional FMEA. We have a dual avionics system. Driven by safety analysis, we need to perform a functional FMEA only for miscompare function. Miscompare function is not a stand alone function. The circuits, such as microprocessor and memeory, which do miscompare is shared by other functions. I could not find any guidelines about this kind of functional FMEA in ARP4761 or ARP5580 or any FMEA books. I would appreciate if I can get help on this issue.
Regards, Michelle Li
Posted by: Nicole
Date posted: Fri Nov 15 8:27:57 US/Eastern 2002
Subject: AMSAA or Observed MTBF??
I encountered a problem during my growth testing. After a period of 1500hrs of testing and i collected 4 failures. Should i use the AMSAA model to compute the results or simply divide the test duration by the number of observed failures? In this case i have only 4 failures so which method is more accurate? The AMSAA model passed the Goodness of Fit Test however. I understand taht AMSAA model is not too suitable when the number of failures are too small right?