On Tue, 25 May 2004 23:01:01 -0400, (Peter
Stickney) wrote:
snip
wouldn't "corruption" mean a faulty hard drive/memory unit that just
needs to be replaced? Surely that could be done a small amount of time
although can't see the point of the RAF cranking out so many
two-seater Tffies for training purposes. whats the point of buying the
advanced version of the Hawk then if their wasting money on pricey
trainer version of the typhoon?

It's unlikely to be a hard drive. (There shouldn't be one at all, for
a system like that)
Corruption, in the Real TIme System context, such as a Flight Centrol
System, ir Data Acq, or other such, menas that the program is stomping
all over its volatile data. In other words, the airplane doesn't know
where it it, what it has done, or what it's doing now. If you know teh
systems, and can read teh clues, it can be even worse than that. Many
real time systems copy their inital programs & state from non-volatile
storage (Prom, Eprom, or EEprom, or possibly Flash) to RAM to actually
run. (Far better access times with RAM). in that case, it's entire
possible for the system to stomp all over the running program, as
well. (Fandango on Core) wiping all of teh current state out.
Having this happen in flight would be Very, Very, Very Bad.

Heres a portion of the executive summary:-

"1.4 Landing Gear Computer

1.4.1 At least twelve failures of the Landing Gear Computer (LGC) have
occured since it was productionised for Series Production Aircraft.
Although modifications to the LGC were introduced following initial
failures, a number of subsequent failures have occurred. These
failures have been unpredictable, and have caused incidents whereby
aircraft have had invalid Landing Gear indication and/or loss of
braking. Recommendations to reduce the impact of invalid Landing Gear
indication and loss of braking have been provided.

1.4.2 It is believed by industry that the problems lie with Electronic
Programmable Logic Devices (EPLDs) inside the LGC; however, the causes
of the failure are not fully understood. Multiple failures of these
ELPDs may cause a corruption of the Nose, and the Left or Right Weight
on Wheels (WoW) Solid State Relays (SSR). There remains an
unquantified risk that the SSRs’ corruption could result in a change
in Flight Control System status from FLIGHT to GROUND, which would be
immediately catastrophic. There is no feasible practical mitigation
for such an event, making it UNACCEPTABLE.

1.4.3 It is therefore recommended as ESSENTIAL that the LGC failure
modes are investigated, understood, and, if necessary, rectified
before release to service. "

Cheers





John Cook

Any spelling mistakes/grammatic errors are there purely to annoy. All
opinions are mine, not TAFE's however much they beg me for them.

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