Fuel Transfer????

[Tom Garrick]

Hey guys.
After 5 years N82092 (F21B) is about ready to fly again. Engine was run last week.
Put your thinking caps on. John put five gallons in each wing to run the engine. Two days later there was one to two gallons in the right wing and eight to nine in the left. A/C was levil. Fuel two inches higher in left tank with a spirit levil. After taking off the right cap, the fuel leviled out. The left cap has a small vent hole in it. The right cap does not.
Interresting problem.

Tom Garrick

[Hank Jarrett]

Re: Fuel Transfer????

Not really much mystery. The temps rose quite a bit last week, and the baro pressure changed too. The right tank was sealed with cold, low pressure air on top of the fuel. As the temprature and pressure changed the fuel was pushed (sucked) to the other tank.
You might want to make sure you have the right cap on your tank. I have never seen a sealed cap on a wing tank.
Hank

[dennispip]

Re: Fuel Transfer????

I think the forward facing fuel vent on top of the plane only vents the left tank. I am not positive about that, however, but it must be the case if the fuel transferred in response to the temp and bar pressure. If that is the case, the fuel cap with the vent should be put on the right tank to prevent that from happening. I guess they must expect the non-vented cap to always go on the left side only and that everyone knows there are different caps for the left and right tanks.

It would be difficult to imagine that both caps are not vented in case something like a bee would plug up the vent up on top and that could cause a problem with fuel getting out of the left tank to where it needs to be when you most need it.

See if any other F21Bs around there have only one vented fuel cap. I would want both vented if there is not a good reason to do so.

It is hard to imagine that there are non-vented caps made, but I suppose it is possible. Are both caps identical otherwise or did you get a "new" one somewhere along the way?

Congrats on getting you plane back together,Tom, and hope all is well with you and your family!

[Tom Garrick]

Re: Fuel Transfer????

Dennis, One is a "new" one and I think they both should have a small vent hole.

Blue side up!

Tom

[Dick Smith]

Re: Fuel Transfer????

Taylorcraft factory site @ http://www.taylorcraft.com/zencart/i...ex&cPath=40_47 lists: PN A-360

as a "sealed gas cap for wing tank" under the category relating to Fuel System Installation for F-19, F-21 & 85 hp.


For what it's worth...! Dick

[Hank Jarrett]

Re: Fuel Transfer????

I have a sealed, un-vented cap for my 41 BC-12-65, but it is painted bright red and is supposed to be exchanged for the one with the fuel quantity wire and float. I never leave the float cap in the tank when not flying because water will run down the wire into the fuel. It is bright red so it is like a big warning light from inside the plane to put the right cap on before flying. The engien doesn't run long with the unvented cap. Probably just long enough to clear the end of the runway on climb out.
Hank