Large commercial aircraft will have multiple magnetic compass master units distributed throughout the fuselage. Three redundant readings are common. If, during a flight, one of the compasses deviates, the pilots can confirm the correct heading from the other two. If magnetic cargo deflects one compass before takeoff, the flight will have lost its acceptable level of redundancy. At that point, a compass failure in flight could leave the pilots with three different compass readings and no way of knowing which is correct. Many cargo aircraft are older airframes that might be more susceptible to such problems. Some cargo operators still fly Boeing 727s, last built in 1982, and there are even some operators using Douglas DC-8s, last built in 1972.
Ted Eckert Compliance Engineer Microsoft Corporation [email protected] The opinions expressed are my own and do not necessarily reflect those of my employer. -----Original Message----- From: Price, Edward [mailto:[email protected]] Sent: Monday, July 25, 2011 8:56 AM To: [email protected] Subject: Re: Loudspeaker Certification as Dangerous goods I can only think of the possible effect a DC magnetic field might have on the magnetic compass. This is what Section 15, Magnetic Effect, of DO-160F, is designed to test. Ed Price [email protected] WB6WSN NARTE Certified EMC Engineer Electromagnetic Compatibility Lab Cubic Defense Applications San Diego, CA USA 858-505-2780 Military & Avionics EMC Is Our Specialty > -----Original Message----- > From: [email protected] [mailto:[email protected]] On Behalf Of Ken Javor > Sent: Monday, July 25, 2011 8:32 AM > To: [email protected] > Subject: Re: Loudspeaker Certification as Dangerous goods > > Everyone seems to acknowledge some hazard from a dc magnetic field. For my > own edification, other than compass-safe distance, what is the hazard of a > dc magnetic field to an aircraft? > > Ken Javor > > Phone: (256) 650-5261 > > > > From: Doug Kramer <[email protected]> > > Date: Mon, 25 Jul 2011 08:55:59 -0500 > > To: "[email protected]" <[email protected]> > > Conversation: Loudspeaker Certification as Dangerous goods > > Subject: RE: Loudspeaker Certification as Dangerous goods > > > > Also, keep in mind if you ship multiple speakers in a box, how they are > > positioned in the box relative to each other has a huge effect on the fields. > > -Doug Kramer > > > > -----Original Message----- > > From: [email protected] [mailto:[email protected]] On Behalf Of John > Woodgate > > Sent: Sunday, July 24, 2011 11:07 AM > > To: [email protected] > > Subject: Re: Loudspeaker Certification as Dangerous goods > > > > In message <[email protected]>, dated Sun, 24 Jul 2011, > > Scott Douglas <[email protected]> writes: > > > >> Would it be necessary to measure every speaker, one of a series, or the > >> biggest one we make and use that to cover all? > > > > The strength of the external field depends on constructional details, > > not size. If you need to do tests, you need to test one of every product > > (barring variants with different impedances), at least. > > -- > > OOO - Own Opinions Only. Try www.jmwa.demon.co.uk and www.isce.org.uk > > John Woodgate, J M Woodgate and Associates, Rayleigh, Essex UK When > > I point to a star, please look at the star, not my finger. The star will > > be more interesting. - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]> - ---------------------------------------------------------------- This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. To post a message to the list, send your e-mail to <[email protected]> All emc-pstc postings are archived and searchable on the web at: http://product-compliance.oc.ieee.org/ Graphics (in well-used formats), large files, etc. can be posted to that URL. Website: http://www.ieee-pses.org/ 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]>
