Ken:
I have never had to do anything for DO-160 testing other than report test data taken in a lab environment. The most recent test I did was to prove that an RFID would go into a prolonged "sleep" mode when a box of maybe a few hundred of them was loaded as cargo on a commercial airliner. As such, all we had to do was the Radiated Emission test. I created a good test report document (lab facilities, equipment operation, traceability, setup drawings and photos, graphical and tabular acquired data, data analysis) which the manufacturer submitted to the FAA along with other documentation, and the FAA approved the whole thing without any involvement of a real aircraft. In the military world, you generally know what platform that your gadget will be integrated into. Here, despite the fact that you may have easily passed 461, the final say is still a system integration test on the flight-line and in-flight with the real platform. But for the commercial world, you are much more likely to need your gadget to work with many platforms, so system integration testing is almost infinite, and you have to rely on the DO-160 validation. Ed Price El Cajon, CA USA From: Ken Wyatt [mailto:[email protected]] Sent: Wednesday, May 09, 2012 12:57 PM To: [email protected] Subject: [PSES] DO-160G Interpretation Hi Group, I have a client that makes air conditioners for aircraft. They need to replace an obsolete fan (no longer available) with a newer version. Both versions have been tested for CE and RE and both pass the Category M limits by very good margins. Here's where it gets interesting and where I need some advice. Apparently, they have been told by their local FAA engineer that while they meet the limits of DO-160G Cat M, they must demonstrate compliance by (a) installing their air conditioning system aboard (not sure how many) aircraft to ensure there's no interference issues OR (b) show the before and after emission plots to a DER (designated engineering representative) who witnesses the test and who recommends to the FAA to approve/disapprove. But get this...the "after" plot must be at or below the baseline "before" plot - at least in the critical frequency notches. The advantage of (b) is that the system does not need to be "flight tested" on X-number of aircraft. I don't believe any of the above (a) or (b) are written down in the standard...merely someone's opinion. The clients BIG ISSUE is that the original fan was a simple brush commutator motor, while the replacement contains an electronic controller. They've added a couple good-quality X2Y bypass capacitors to the power leads, as well as gasketing around the access cover, which knocks down the emissions by 20+ dB - well under the limit - but there are frequency bands where the emissions are a little higher than the baseline motor emissions. However, they are currently a good 10 to 25 dB under the limit. If their baseline motor was more complicated (i.e., had electronics), I'd suspect the A-B comparison would have been much easier. Here's a case where it pays to not have too good of a baseline! Now the questions... 1. Is the client's understanding of the qualification procedure correct? If not, then what? 2. I presume that the emission limits as specified in DO-160G have been calculated to reduce the risk of interference. Is it not sufficient to pass the limits or do they really need to jump through the additional qualification hoops described above? 3. Apparently the FAA engineer in (un-named city) has been proven to be more rigorous in interpreting the standard than other FAA offices. Is it fair to "shop around" for an FAA office with more reasonable interpretations? Thanks in advance, Ken _______________________ Kenneth Wyatt Wyatt Technical Services LLC Woodland Park, CO Email Me! <mailto:[email protected]> | Web Site <http://www.emc-seminars.com> | Blog <http://design-4-emc.com/> Subscribe to Newsletter <http://www.emc-seminars.com/Newsletter/Newsletter.html> Connect with me on LinkedIn <http://www.linkedin.com/in/kennethwyatt> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. 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