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Old 4th May 2011, 07:28
  #641 (permalink)  
snowfalcon2
 
Join Date: Dec 2005
Location: Finland
Posts: 242
Recorder Locations (distributed memories)

There is obviously some merit to rethinking the CVR/FDR data recorder concept. One proof point is (if I understand correctly) that BEA is indeed searching also for the other memory units in the aircraft, i.e. within the flight deck and engine FADEC systems, even though they are not hardened to the extent of the CVR/FDR memory units.

However, a simplistic relocation / multiplication of units brings its own problems.

- The added dead weight and space requirement of each unit and its power feed. As noted before, it performs a critical function at most only a few times in the lifespan of the aircraft.

- Each unit needs a reliable incoming data feed with all recorded parameters. For obvious reasons it would be impractical to feed each recorder with primary data (i.e. individual electrical/pitot/etc. sensor lines). This implies a bus structure and furthermore a need for multiple data buses, otherwise the "single point of failure" of the recording system just shifts from the CVR/FDR to the bus multiplexer equipment. Multiple buses and multiplexers add more weight.

- Increased amount of wiring. The data buses could probably be light optical fibers, but even so I presume there is usually not much extra wiring space in an aircraft. So the installation probably needs to be considered at the basic design phase. This means the time to deployment is long.

- An option might be to have wireless transmission of the data to the recorders, but that brings with it some radio spectrum management issues. To exaggerate a little, you probably don't want the recorders to be susceptible to your seat neighbour's computer Wi-Fi. (I remember Gulfstream has done some trials of using wireless links - IIRC for spoiler actuators - but this is not a trivial issue).

- Looking at recent crashes and the CVR/FDR searches, in my mind the eventual success rate of finding the CVR/FDR in a usable state and extracting the data has been remarkably high. The main problem has been to find the actual aircraft wreck - once it is found the recorders have also eventually been found fairly quickly, actually in each recent case that comes to my mind.

- From the above it follows that a wiser way of spending R&D and development money, with a higher benefit, could be to improve pinger and CVR/FDR locating techniques, rather than to just add recording equipment to the airplanes.

Just my 2 cents.

Last edited by snowfalcon2; 4th May 2011 at 08:08. Reason: Clarification
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