NW_Pilot's Trans-Atlantic Flight -- All the scary details...

Neil Gould writes:

The avionics in the aircraft that I fly reboot when they are powered off
then on. No synchronization required.

But when multiple reboots occur, each at the same point after the
previous boot, it's not a power problem, it's a software problem.

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Doug writes:

They landed with one engine (no pilot overide) and the Cessna engineers
came out and did a lot of head scratching. I do not know what the final
diagnosis was on that one.

I'd say the best diagnosis is to replace the jet with the FADEC with a
different jet that lets the pilot control the engines.

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Gig 601XL Builder writes:

No a hardware problem could have also been the cause.

Not for synchronized reboots. Those come from software.

An electrical short
caused by the "hacked" wiring sounds like an excellent place to start
looking.

A short will either have no effect or it will prevent the system from
operating at all. It will not reboot the system in perfect
synchronization with the software.

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Neil Gould writes:

What gives you the impression that there was some "synchronization with
the software"? Nothing NW_Pilot reported would suggest it, and the
frequency and number of reboots implies something completely different.

His description suggests that the system booted and went through the
same software process over and over. That is not a hardware problem.

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Mxsmanic wrote in
:

Neil Gould writes:

What gives you the impression that there was some "synchronization with
the software"? Nothing NW_Pilot reported would suggest it, and the
frequency and number of reboots implies something completely different.

His description suggests that the system booted and went through the
same software process over and over. That is not a hardware problem.


Care to put some money on that conclusion? Many, many years ago we
encountered a similar problem. Every symptom said it was software,
especially when one operating system would not encounter the problem yet
another one did. After several weeks we managed to isolate the exact
channel program sequence which caused the error. The hardware developers
confirmed that the channel program sequence was indeed valid. Further
investigation showed it to be an error in a circuit card supplied with a
field upgrade kit. Since each operating system used a slightly different
channel program to accomplish the same thing, the error only manifested
itself on one system.

--
Marty Shapiro
Silicon Rallye Inc.

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Marty Shapiro writes:

Care to put some money on that conclusion?

I have no money to spend on gambling, but I'm confident that the
conclusion is correct.

Many, many years ago we
encountered a similar problem. Every symptom said it was software,
especially when one operating system would not encounter the problem yet
another one did. After several weeks we managed to isolate the exact
channel program sequence which caused the error. The hardware developers
confirmed that the channel program sequence was indeed valid. Further
investigation showed it to be an error in a circuit card supplied with a
field upgrade kit. Since each operating system used a slightly different
channel program to accomplish the same thing, the error only manifested
itself on one system.

Those are the stories one remembers _because_ they are such remarkable
exceptions to the rule. I think the explanation in this case is much
more mundane: bad code.

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Recently, Mxsmanic posted:

Neil Gould writes:

The avionics in the aircraft that I fly reboot when they are powered
off then on. No synchronization required.

But when multiple reboots occur, each at the same point after the
previous boot, it's not a power problem, it's a software problem.

There is no evidence that this was the case. In fact, that is not at all
what NW_Pilot reported.

Neil