Fuel Drip Containment

"C J Campbell" wrote in message
...
Don't fill your plane before putting it away?

We turn the fuel valve off or turn it to left or right tank -- this seems
to
mitigate the problem considerably, though I am not sure why it does this.

Because in any position besides the BOTH setting, it prevents fuel from
flowing between the tanks... or more precisely, from the (slightly) upper
tank to the lower tank and out the lower tank's fuel vent.

Eric

"Eric Miller" wrote in message
...
| "C J Campbell" wrote in message
| ...
| Don't fill your plane before putting it away?
|
| We turn the fuel valve off or turn it to left or right tank -- this
seems
| to
| mitigate the problem considerably, though I am not sure why it does
this.
|
| Because in any position besides the BOTH setting, it prevents fuel from
| flowing between the tanks... or more precisely, from the (slightly) upper
| tank to the lower tank and out the lower tank's fuel vent.
|

Okay, that much I knew, but why doesn't the lower tank just empty itself?
Does it need the pressure from the higher tank in order to start siphoning
out the fuel vent?

"C J Campbell" wrote
Okay, that much I knew, but why doesn't the lower tank just empty itself?
Does it need the pressure from the higher tank in order to start siphoning
out the fuel vent?

I think the lower tank does empty itself... but just until it gets to the
level of the fuel vent.
In the BOTH setting, they'll both empty to the level of their respective
vents.
Keep in mind that the right tank is vented to the left tank, and the left
tank is vented overboard, so if possible, it might help to make the right
tank the lower one.

Eric

Eric Miller wrote:


I think the lower tank does empty itself... but just until it gets to the
level of the fuel vent.
In the BOTH setting, they'll both empty to the level of their respective
vents.

There is only one vent, under the left wing. If fuel expands it runs in
a line between the left and right tanks. This line is above the tanks.
Fuel will also go thru this line if the selector is on both, the tanks
are full or near full and the plane is not level. Move the selector to
either right or left and this won't happen. If left on both the tanks
will level themselves thru the selector.

Hm. I guess I could rotate the whole airport so that my hangar faces lefthand
UPHILL instead of downhill, but it is going to take a moby-large bulldozer to do
it.

Jim



-Keep in mind that the right tank is vented to the left tank, and the left
-tank is vented overboard, so if possible, it might help to make the right
-tank the lower one.
-
-Eric
-
-

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

C J Campbell wrote:

Okay, that much I knew, but why doesn't the lower tank just empty itself?
Does it need the pressure from the higher tank in order to start siphoning
out the fuel vent?

It doesn't siphon, it flows. Without the fuel from the other tank it
can't flow.

Yes, I thought I said that I could slow it down, but not stop it. As you can
see, others (ad infinitum, ad nauseum) will tell you the simple physics of
parking an airplane with the outside fuel vent downhill.

Jim


"C J Campbell"
shared these priceless pearls of wisdom:

-Don't fill your plane before putting it away?
-
-We turn the fuel valve off or turn it to left or right tank -- this seems to
-mitigate the problem considerably, though I am not sure why it does this.
-

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

Not an acceptable fix. Liquid fuel in an open container is not where I wanted
to go. I could just have used a bucket on the floor instead of taking a chance
on bending the vent with a quart (1½ #) of fuel hanging on the line.

But thanks for trying.



"Sven"
shared these priceless pearls of wisdom:

-Hi Jim,
-
- I have seen people hang an empty plastic oil bottle on the fuel vent to
-catch the dripping fuel on Cessnas. Have you tried this? It shouldn't be too
-much of a fire hazard and will save your hangar floor. Just make sure that
-you drain the bottle regularly because the angle it sits on the vent, it
-won't hold a whole quart of fuel. Using a GATT jar or some other filter, you
-can reuse the fuel.
-
-"Jim Weir" wrote in message
.. .
- Snarly Charlie, the 182, has the classic "Cessna drip" from the fuel vent
-when
- the tanks are filled and the hangar gets warm. I've tried everything I
-know to
- stop it, but all I can do with all the mechanical fixes is slow it down.
-

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

How about a piece of tygon tubing with a inside diameter the size of the
vent tube. Let that hang (or support it with the wing strut) and let it
drain into a gas can. If you are careful you might even be able to reuse
it. I am lucky, my 172F has never had this condition. A friend with a
150 always had it and only fueled when he got ready to fly.

I use a short piece of hose with some wire mesh in it and a orange
"flag" hanging from it. I put that over the vent tube to keep the pesky
bugs from building a nest in it. Orange flag reminds me to remove before
flight.

"David Lesher" wrote in message
...
It might be interesting to take a container with some small quantity
of gas-damp kitty litter and ignite it safely -- ie well clear of
any burnable stuph and with a 6' pole to set it off.

The kitty litter won't burn. The gas fumes will, and I'd assume will
the heat will evaporate 'trapped' gas....but slowly.

Just use the fuel soaked kitty litter in the litter box. It will keep your
cat from smoking! ;-)

Avgas or auto fuel will smell better than the used litter box.