On Mon, 02 Oct 2006 11:27:24 GMT, John Theune
wrote in wI6Ug.876$Pk2.497@trnddc08:

I'm a software engineer and I've dabbled a little in real time systems
and there are many things that can cause a system to reboot.

Would division by zero be one of them?

It might be a **** poor design or it might be something else. NW_pilot
has not given us enough data to know ( because he did not have the data
either )

Perhaps. Here's what is on Mr. Honeck's web site at the URL he
provided at the beginning of this message thread
http://www.alexisparkinn.com/nwpilot's_tranatlantic_flight.htm:

[Day 2]
After switching to the aircraft fuel (from the ferry tank) strange
things started happening. The 100-gallon ferry tank went dry
after only 7 hours, burning 8 to 9 gallons per hour! Something
just did not add up...
[...]

Then, the G1000 started to go nuts, with the fuel indicators
displaying red X's. Next, I received a CO2 detector failure, then
GPS-1 failure!
[...]

When the G1000 got done rebooting, I found myself missing my
airspeed indicator and fuel gauges -- and it was now displaying a
bunch of other errors. Assessing my situation, I figured that I
had no fuel gauges, the G1000 is continually rebooting, possible
CO2 in the cabin, AND an apparent fuel leak!
[...]

As I grind closer and closer to Narsarsuaq, at about 60 miles out
they send up a rescue chopper, locate me, and guide me in, since
I am unable to make the NDB approach with the G1000 rebooting
itself. (The ADF display is tied to the G1000's HSI.)
[...]

[Day 3]
We finally figured out that the instructions for the ferry tank
were not correct, and really need to be changed before the company
installing the tank kills someone.

The problem was the ferry tank's fuel return line was over
pressurizing the aircraft tanks, causing fuel to vent overboard.
To prevent this, what needed to be done was to FIRST run the
aircraft's left tank down till it was almost empty, THEN turn on
the ferry tank.

The instructions with the ferry tank said only to "Climb to
altitude, then switch to the ferry tank and turn off the aircraft
fuel", then run it till the fuel level hits a mark on the ferry
tank's fuel level indicator. These instructions turned out to be
totally incorrect!

Even Cessna engineering was surprised that the FAA had approved
the instructions for the ferry tank setup, because it also caused
the G1000 to go nuts. Apparently the added pressure in the fuel
tanks pushed the floats in the fuel tank up, which got the Garmin
confused, causing an error that made it reboot. The loss of the
airspeed indicator was caused by fuel vapors entering the pitot
tube -- which also caused the CO2 detector failure!
[...]

[Day 11]
Then the tach started being erratic, saying that my RPMs were 4000
-- yeah, right! Then it went Red X. OK, Garmin & Cessna, you
need to have better quality control. After everything else that
has happened, this makes me not want to every own a newer model
Cessna, or anything with a G1000.

The biggest problem is Garmin does not issue final reports but in this
cause it may be possible to find out why. I agree that a[n] out of range
fuel sensor should not cause a system reboot. I just went back and
re-read the story and realized that this was not truly a garmin problem.

Perhaps you are correct, but It would seem that there is a lot of
corroborating evidence absent at this time.

The modified fuel system caused the problem and those additions are
outside the design envelop of the garmin system.

Would you care to share the information to which you refer, detailing
the "design envelope of the Garmin system?"

It would appear at first glance that the condition that caused the problem
( over pressure in the fuel tank due to excess fuel could not happen in a standard
system and so it was not forseen in the system design)

Typically wing tanks are filled to the brim of the filler neck.
Presumably that leaves some air trapped in the tank. Without knowing
the exact placement of the fuel vent pipe intake within the tank, it
is difficult to confirm an over pressure condition in this case.
Absent knowledge of how Mr. Rhine came to his "over pressurizing"
conclusion, it is difficult to substantiate it as fact. Might not the
venting fuel have been merely excess fuel draining from the tank as it
was designed to do when the tank is over filled? After all,
presumably it is the same fuel pump operating in both the factory
designed fuel system and the aux fuel system.

Bottom line is that this was a modified system and to hold garmin responsible and use
that are [sic] a reason not to have advanced avionics is not good idea.

Perhaps.

I thought you felt it would be more appropriate to reserve judgment
until more information was available.