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

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.

The Aux system used it's own fuel pump and it was tied in after the aircraft
fuel shut off valve.

John Theune writes:

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. It might
be a **** poor design or it might be something else.

It's always poor design, unless power is cut to the system. This is
something that many software engineers don't understand.

The aircraft does not freeze in suspended animation while the system
reboots.

I just went back and
re-read the story and realized that this was not truly a garmin problem.

If the G1000 rebooted, it's a Garmin problem (although there may be
others).

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

Rebooting is not an appropriate response to excursions outside the
envelope.

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

Why not? Does somebody have to die first?

--
Transpose mxsmanic and gmail to reach me by e-mail.

Larry Dighera writes:

It would seem that Airbus has successfully grappled with this issue.

On the contrary, Airbus has shown just what a serious problem it is.

Perhaps Cessna and Garmin should get a clue from them.

Perhaps installing a video game in place of standard avionics isn't a
good idea.

--
Transpose mxsmanic and gmail to reach me by e-mail.

On Mon, 2 Oct 2006 09:14:15 -0700, "NW_Pilot"
wrote in
:


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.

The Aux system used it's own fuel pump and it was tied in after the aircraft
fuel shut off valve.


So you're saying, that there was a new fuel selector valve placed in
the fuel line between the normal On/Off Cessna fuel selector valve and
the engine?

And the aux fuel system consisted of a fuel quantity indicator, the
aux fuel tank and vent, an additional fuel pump and electrical switch,
and a single fuel line leading from the aux fuel tank to the added
fuel selector valve?

john smith wrote:
The problem with that statement is that many GA pilots haven't even
read the book to know what it says.

What's the ISBN of this book?

The aircraft does not freeze in suspended animation while the system
reboots.

It does for everything you fly...

On Mon, 02 Oct 2006 16:41:50 -0000, Jim Logajan
wrote in :

john smith wrote:
The problem with that statement is that many GA pilots haven't even
read the book to know what it says.

What's the ISBN of this book?

I believe Mr. Smith is referring to the aircraft's POH.

wrote:
I agree that continuous rebooting is a bad idea.

Just FYI, NASA's Mars Spirit rover got itself into a continuous reboot
cycle too:

http://en.wikipedia.org/wiki/Spirit_rover

I've been involved in a couple of projects where we considered adding an
external hardware watchdog reboot system. (These are simple systems that
must be sent a heartbeat pulse periodically by the application, otherwise
the watchdog assumes the app died and does a hard reset of the application
system.)

Automatic reboot is of course a last resort, but given a choice between a
distant system that freezes up entirely and all hope of recovery is lost
and one that reboots into a state long enough to allow a small chance to
salvage the situation, I think the latter is preferred.

but given a choice between a
distant system that freezes up entirely...

Different application. Here we have a live pilot who can make a
decision and push the button, but the computer decides to push it for
him. There, it's completely on its own, and a last resort is
worthwhile. One just make sure the last resort doesn't get too
impatient.

Jose
--
"Never trust anything that can think for itself, if you can't see where
it keeps its brain." (chapter 10 of book 3 - Harry Potter).
for Email, make the obvious change in the address.

The fact is, you're always going to get flamed, no matter what you do.
You can't worry about it.

I agree. What's to worry about? Flames aren't fatal. They don't even
hurt. :-)

Well, as you know I am immune to flames, too -- but I often hear from
"lurkers" who say they don't post for fear of getting lambasted.

Not everyone is a thick-skinned as we are, and -- if we want GA to grow
-- we need to be welcoming everyone into this group with open arms, not
poison pens.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"