greendot:
If (i stress if) EMI was present it could have caused the spar valve control relays to close and the APU fuel s/o vlv relay to open, possibly latched in that position when power was restored until the EMI source disappeared, returning the system to a normal logic condition..
How?
Please provide a plausible scenario to drive the relatively high current
DC components involved, via spurious radio signals, keep them engaged, and then release them when the radio signal is removed. I won't ask you to explain the presence or strength of said signal, merely to describe the electrical activity of the aircraft systems responding, esp why other systems were apparently completely unaffected, only the fuel control.
I believe it is time to take the strop to Occam's Razor.
http://www.airmech.co.uk/forums/showthread.php?t=3650
This gives a good overview and history. CAUTION: link to PDF file:
http://www3.verticalgateway.com/port...s/hirfnprm.pdf
Link to FAA Final rule on HIRF certification as of Feb 2008:
http://rgl.faa.gov/Regulatory_and_Gu...E?OpenDocument