Ted, Thanks, you confirmed my thoughts on what might be happening inside these gauges, even if form, fit and function remain unchanged. The DO-160C qualification was likely due to the qualification by similarity to an earlier model. The date of qualification was 1997, and that's when DO-160D was released. Ken Javor
Phone: (256) 650-5261 > From: <[email protected]> > Date: Fri, 14 Dec 2007 08:29:49 -0600 > To: <[email protected]> > Subject: Re: FAA TSO requirements > > I have only a basic understanding of EMC for avionics and I hope that > another forum member can provide more information, but I am willing to > contribute what I know. > > First, I thought that RTCA/DO-160D superseded revision C about 10 years > ago. Revision D updated the susceptibility testing, in particular the RF > susceptibility test methods. Avionics tested to the older standard might > not meet the new standard. > > Second, there have almost certainly been changes over the past 10 years > that would significantly affect the EMC performance of any electronic > device. One problem I have frequently encountered has been die shrinks > from the semiconductor manufacturers. As the semiconductor manufacturers > move their highest performance parts to lines with smaller features, they > are left with older fabrication lines with excess capacity. They often > migrate all of their components to smaller feature sizes. It lets them get > more dies out of a single wafer and increases profit. Often, everything is > shrunk without changing the relative dimensions of the gates. This can > affect susceptibility, and it can sharpen the edges increasing the > broadband noise in emissions. The smaller gates and conductors can also be > much more susceptible to EMC. > > In short, I would think it quite reasonable to requalify a design that is > at least 10 years old. > > Ted Eckert > American Power Conversion/MGE > http://www.apc.com/ > > The items contained in this e-mail reflect the personal opinions of the > writer and are only provided for the assistance of the reader. The writer > is not speaking in an official capacity for APC-MGE or Schneider Electric. > The speaker does not represent APC-MGE's or Schneider Electric's official > position on any matter. > > > > Ken Javor > <ken.javor@emccom > pliance.com> To > Sent by: <[email protected]> > [email protected] cc > > Subject > 12/13/2007 10:18 FAA TSO requirements > PM > > > > > > > > > > Forum members, > > Lend me your ears. > > I am reviewing RTCA/DO-160C qualification data for some aircraft engine > monitor gauges (rpm, temperature at various points). These devices date > back > ten years, plus they were qualified by similarity to an earlier design - > how > much earlier is not stated. > > My question is whether any forum members have a feel for how tight this TSO > process really is. It is hard for me to imagine that every part in these > gauges is built exactly like it was ten years ago, or more. I can see > where > the individual component part numbers would need to be the same, but is > there any guarantee that the dc/dc converter manufacturer is building his > product the same way, even if he uses the same part number? What about > integrated circuits in general over such a span of years? > > Thanks in advance, > > Ken Javor > > Phone: (256) 650-5261 > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc > > - > ---------------------------------------------------------------- > This message is from the IEEE Product Safety Engineering Society > emc-pstc discussion list. Website: http://www.ieee-pses.org/ > > To post a message to the list, send your e-mail to [email protected] > > Instructions: http://listserv.ieee.org/request/user-guide.html > > List rules: http://www.ieee-pses.org/listrules.html > > For help, send mail to the list administrators: > > Scott Douglas [email protected] > Mike Cantwell [email protected] > > For policy questions, send mail to: > > Jim Bacher: [email protected] > David Heald: [email protected] > > All emc-pstc postings are archived and searchable on the web at: > > http://www.ieeecommunities.org/emc-pstc - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
