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Old 29th Nov 2008, 00:38
  #80 (permalink)  
Join Date: Jun 2005
Location: Citizen of the World
Posts: 174
There have been numerous instances of ELAC failures in the recent past on the worldwide A320 fleet. (ELAC = Elevator Aileron Computer which controls pitch and roll). These have allegedly been put down to a faulty batch - made by Thales, I think. However, a single ELAC failure should simply be a non-event and even a dual ELAC failure should only result in the aircraft switching from Normal Law to Alternate Law. In Alternate Law it would still have most of the flight envelope protections but would revert to Direct Law when the gear is put down. Even in Direct Law it is easy to control being a bit like a normal non-fly-by wire aircraft but a bit sloppy in control response. Still easy to fly, though.

The Qantas A330 incident seems to have been related to spurious speed signals from the ADIRS so the two may not be connected in any way. In the Qantas incident, why did the systems not disregard the spurious IRS speed if the other two ADIRS were giving a correct one? And did this ANZ A320 have the same ADIRS as the Qantas A330. This unit is fitted to lots of A320s, I understand.

The implications for all 320s are enormous if it is discovered that there's a flight control problem that wasn't known up to now. Aircraft flown by very experienced airline pilots don't usually suddenly dive into the sea. Whatever happened in this case, happened so fast that there was no time for a radio call. The DFDR and CVRs should tell us quite soon (if the French are honest about it - there are hundreds of thousandsof jobs depending on these aircraft!). Would it be a surprise to discover that the recorders were damaged and could give no useful information.
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