I do realize there is a big difference in the use of cable shielding/screening between general and commercial aviation practices. However the same general aviation aircraft that get by with little or no cable shielding/screening also have no electronic critical flight controls, so it is a wash. Any aircraft with flight controls qualified to RTCA/DO-160A will also have its maximum degree of automation limited to using the autopilot, possibly in conjunction with navigation inputs from aircraft NAV receivers. Both the rf (coax) and the base-band signal inputs into the autopilot would be shielded in my experience. I would definitely NOT expect personal electronics to interfere with such control systems (except for that all-important radio link).
I would also expect that as an older aircraft gets avionics upgrades, with avionics qualified to RTA/DO-160D, that the cables connecting to the new avionics must be upgraded if the certification is to maintain validity. Specifically, if a new avionics upgrade were form, fit and function compatible with the old part, but required a shielded harness to meet RTCA/DO-160D, then that cable would have to be retrofitted along with the equipment. Am I being overly idealistic and out of touch here? In any case I reiterate: basic systems engineering practices mandate that a (non-rf) signal that carries flight critical information should be piped through the aircraft such that neither cross-talk nor stray emissions from other electronics cause interference. Along these lines, there are those who mourn the passing of the old term, rfi, because the term evoked the concept of RADIO interference, rather than the general term electromagnetic interference, which is global in its meaning. We need to consciously retain the idea that stray (unintentional) rf emissions from non-antenna connected electronics have the potential to create only rfi. ---------- >From: andrew.p.pr...@baesystems.com >To: emc-p...@majordomo.ieee.org >Subject: Re: New EU regulations - civil aviation >Date: Mon, Sep 16, 2002, 1:57 AM > > > Firstly all avionic equipment is qualified to RTCA/DO-160 (European > equivalent EUROCAE ED-14). > All new equipment is test to DO-160D however there is still equipment > installed on aircraft that was originally tested to DO-160A. > Overtime the DO-160 has become more stringent with tighter emission levels > and high immunity test levels which includes HIRF testing. > > There is one problem that arises from this as most of the cabling installed > on the aircraft is unscreened. This is for weight saving reasons. > > Therefore with alot of older aircraft having a mixture of new and old > equipments installed using cabling that is unscreened it is reasonable to > assume that some Passenger Portable devices such as Gameboys, Laptop > Computors, Mobile Phones, etc. will if that passenger happens to be sitting > above a cable run cause interference with one or more aircraft systems. The > UKCAA keeps a log of all reported incidents. > > Regards > Andy > > > Andrew Price > Principal Development Engineer (EMC Specialist) > BAE SYSTEMS Avionics > A125 > Christopher Martin Road > Basildon, Essex > SS14 3EL > > tel: +44 (0) 1268 883308 > email: andrew.p.pr...@baesystems.com > > > > *************************************************************************** > > This email and any attachments are confidential to the intended > recipient and may also be privileged. If you are not the intended > recipient please delete it from your system and notify the sender. > You should not copy it or use it for any purpose nor disclose or > distribute its contents to any other person. > > *************************************************************************** > > ------------------------------------------- > This message is from the IEEE EMC Society Product Safety > Technical Committee emc-pstc discussion list. > > Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ > > To cancel your subscription, send mail to: > majord...@ieee.org > with the single line: > unsubscribe emc-pstc > > For help, send mail to the list administrators: > Ron Pickard: emc-p...@hypercom.com > Dave Heald: davehe...@attbi.com > > For policy questions, send mail to: > Richard Nute: ri...@ieee.org > Jim Bacher: j.bac...@ieee.org > > All emc-pstc postings are archived and searchable on the web at: > http://ieeepstc.mindcruiser.com/ > Click on "browse" and then "emc-pstc mailing list" > ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
