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January 2002

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Subject:
From:
Earl Moon <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 17 Jan 2002 06:18:53 -0600
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David,

I find your post of great interest for several reasons. One is Werner's
accurate comment about physics of failure rings true and loud.

In this post, I find concern, again in light of Werner's other partucular
comment about "nor should there be" as it references predicting reliability
based on a replacement for 217. Hope I got that right.

Though some very significant/large military subs still rely on a document
obololeted over 5 years ago. I mention this because I have been contacted,
again, and many times before concerning using this type material with
"advanced" software packages in an attempt to predict reliability of
whatever device or system.

Not long ago, I worked on a contract wherein I set out to not only do
thermal analysis of an R/F system - from the component level out to the
housing cooling fins. I approached the task from a finite element analysys
standpoint determining what got hot, and how hot, as well as using
engineering principles to effect increased thermal efficiency. The short of
a very long story.

At the same time, management had hired an outside "predictability"
consultant, not to my knowledge by interesting non the less later, using an
"advanced" thermal software modeling package.

Again, to make the story short, I got the job done and the software based
folks came in way out in left field.

I'm not saying I was better, though I got the required results with a design
that worked. I'm saying there may be very good predictability capabilities
out there, but I haven't seen one work as well as HARD WORK.

This brings me to your posting and 217's replacement, or conversion. While I
have no problem with attempting to do considerable "up-front" through DFM/CE
(I think I've expressed this before) while using all possible USEFUL tools
and documentation, I am a reliability persone based on evolutionary, PROVEN
technology. I'm not dispariging those seeking breakthrough as do R&D folks.
It's just that I do most of my work relying on already proven technology and
the data to support its reliability. Of course, I also get the opportunity
to derive that data from experminents and F/A

Earl

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