From: henry@spsystems.net (Henry Spencer)
Newsgroups: sci.space.tech
Subject: Re: Building a space faring vehicle
Date: Thu, 9 Dec 1999 19:02:58 GMT

In article <384E4C72.8D574729@NOSPAM.erols.com>,
rk  <stellare@NOSPAM.erols.com> wrote:
>even certain commercial companies, which are known for high quality and long
>product lifetimes, "burn-in" their instruments while actively running them.  for
>example, a certain manufacturer of lab instruments will place a whole pile of
>them in an oven and run automated diagnostics on them continuously...

There is another trick, useful at the component level although it's not so
clear how to apply it to whole assemblies:  while burning in, rather than
just monitoring for correct operation, measure basic performance
characteristics (e.g., resistance of a resistor) continuously.  Plot them
against time for every part.  Most parts will do the same thing, something
relatively simple and boring, e.g. a slow increase in resistance with time
at high temperature.  Any part which does anything *unusual* -- sudden
changes, reversals of slope, wrong slope, excessively high slope -- you
reject.  Relatively few parts will do that, but they're the ones that are
likely to fail early.  Reportedly this is extremely effective.
--
The space program reminds me        |  Henry Spencer   henry@spsystems.net
of a government agency.  -Jim Baen  |      (aka henry@zoo.toronto.edu)