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

The aux tank was connected directly to the engine after the aircraft fuel
system, Not to the wing and the provided documentation and system
description mentioned nothing about the fuel return to the main tanks.

How would the fuel get to the main tanks in the first place? Is the
engine the only connection? (if so, with the fuel selector OFF that
should block fuel flow to the main tanks). Is there a vent line that
connects them?

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.

On Mon, 02 Oct 2006 18:59:11 GMT, Jose
wrote in :

How would the fuel get to the main tanks in the first place?

Read Mr. Rhine's narrative. The FI system has a fuel return line to
return unused fuel pumped to the engine back to the wing tank(s).

The FI system has a fuel return line to
return unused fuel pumped to the engine back to the wing tank(s).

Is this dumb, or is there a good reason not to return fuel to the tank
whence it came, in this case, the ferry tank?

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.

"Jose" wrote in message
m...
The FI system has a fuel return line to
return unused fuel pumped to the engine back to the wing tank(s).

Is this dumb, or is there a good reason not to return fuel to the tank
whence it came, in this case, the ferry tank?

Jose

There would probably be a significant amount of under the cowling work that
would have to be done. So the good reason is cost.

On Mon, 02 Oct 2006 19:23:12 GMT, Jose
wrote in :


Is this dumb, or is there a good reason not to return fuel to the tank
whence it came, in this case, the ferry tank?

I suppose it was an engineering expedient to simplify the
installation.

Recently, Jose posted:

The FI system has a fuel return line to
return unused fuel pumped to the engine back to the wing tank(s).

Is this dumb, or is there a good reason not to return fuel to the tank
whence it came, in this case, the ferry tank?

I think it's short-sighted, as it didn't consider the entire fuel system.
From the description that NW_Pilot gave, the aux fuel system seems more
like a kludge than something that was designed.

Neil

"Jose" wrote in message
m...
The aux tank was connected directly to the engine after the aircraft fuel
system, Not to the wing and the provided documentation and system
description mentioned nothing about the fuel return to the main tanks.

How would the fuel get to the main tanks in the first place? Is the
engine the only connection? (if so, with the fuel selector OFF that
should block fuel flow to the main tanks). Is there a vent line that
connects them?

Excess fuel from the engine is returned to the main tanks. Twin Cessna's
are the same way; if you switch to the aux tanks before burning a certain
amount out of the mains (90 minutes for the large aux tanks) the mains will
overfill and vent overboard before the aux tanks are empty.

Allen

"Allen" wrote in message
. ..

"Jose" wrote in message
m...
The aux tank was connected directly to the engine after the aircraft
fuel system, Not to the wing and the provided documentation and system
description mentioned nothing about the fuel return to the main tanks.

How would the fuel get to the main tanks in the first place? Is the
engine the only connection? (if so, with the fuel selector OFF that
should block fuel flow to the main tanks). Is there a vent line that
connects them?

Excess fuel from the engine is returned to the main tanks. Twin Cessna's
are the same way; if you switch to the aux tanks before burning a certain
amount out of the mains (90 minutes for the large aux tanks) the mains
will overfill and vent overboard before the aux tanks are empty.

Allen


And there is a note in the description of that fuel system that explains
that! Which was not included in the description of the modified fuel system
on the 172.

"NW_Pilot" wrote in message
. ..

"Allen" wrote in message
. ..

"Jose" wrote in message
m...
The aux tank was connected directly to the engine after the aircraft
fuel system, Not to the wing and the provided documentation and system
description mentioned nothing about the fuel return to the main tanks.

How would the fuel get to the main tanks in the first place? Is the
engine the only connection? (if so, with the fuel selector OFF that
should block fuel flow to the main tanks). Is there a vent line that
connects them?

Excess fuel from the engine is returned to the main tanks. Twin Cessna's
are the same way; if you switch to the aux tanks before burning a certain
amount out of the mains (90 minutes for the large aux tanks) the mains
will overfill and vent overboard before the aux tanks are empty.

Allen


And there is a note in the description of that fuel system that explains
that! Which was not included in the description of the modified fuel
system on the 172.

That is true, I am not inferring anything. You would think the tank company
would be familiar enough with the aircraft they are installing tanks into to
have a working (correct) procedure manual. Surely you are not the first to
ferry this particular combination.

Allen

On Mon, 02 Oct 2006 19:32:15 GMT, "Allen"
wrote in :

Twin Cessna's
are the same way; if you switch to the aux tanks before burning a certain
amount out of the mains (90 minutes for the large aux tanks) the mains will
overfill and vent overboard before the aux tanks are empty.

Are you saying that Cessna designed the fuel system that way, and the
FAA certified it? Or are you referring to a ferry tank?

It makes you wonder if the FAA would certify kinking the fuel line
instead of providing a valve to shut off fuel flow. :-)