On 12/03/2014 11:39 AM, Evan Foss wrote: > While I agree with that rant I can say that a lot of higher end stuff > does get environmental testing. My stuff lives in a hotter than > average environment and so I have to consider this. > > Also my father has worked for a few different companies that for > defense and enterprise level hardware had to do these tests. (One even > had an earthquake simulator) > > Yes, of course, various manufacturers test all sorts of stuff! But, these PUBLISHED MTBF numbers all seem to come from the old DESC scheme. When they show 250K hours MTBF for a hard disk drive, you KNOW they are using this methodology. Anybody know of a hard disk drive that will run for a continuous 28 YEARS? NOT very likely.
First, high-rel gear will be very hard to get realistic MTBF numbers on, if you build them and they run for years without failure. Extrapolating that experience will make for wildly varying numbers. So, I admit, fully, that getting a truly valid MTBF number from accelerated life testing of high-rel systems is actually close to impossible! All the makers of avionics stuff have to really beat on their gear, with thermal shock, thermal extremes, condensation, electromagnetic torture, lightning resistance, massive vibration, and so on, to be sure the gear won't break down at the worst possible times. There have been a number of incidents where software glitches, failure of redundant components and wiring problems have come VERY close to bringing down passenger aircraft. There are apparently a few cases where such problems at least contributed to fatal crashes. Jon ------------------------------------------------------------------------------ Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server from Actuate! Instantly Supercharge Your Business Reports and Dashboards with Interactivity, Sharing, Native Excel Exports, App Integration & more Get technology previously reserved for billion-dollar corporations, FREE http://pubads.g.doubleclick.net/gampad/clk?id=164703151&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
