fuel caps and escaping fuel

[N63045]

I have noticed fuel missing from my airplane (L2). I think I know where it is going. I have caps on the two wing tanks that have vents in the form of tubes that are bent forward. It seems that those vents are letting the fuel evaporate.

Does anyone else have this problem? If so, how do you cure it? Am I the only one with fuel caps that have tubes as vents?

[Jim Hartley]

Re: fuel caps and escaping fuel

I have noticed fuel missing from my airplane (L2). I think I know where it is going. I have caps on the two wing tanks that have vents in the form of tubes that are bent forward. It seems that those vents are letting the fuel evaporate.

Does anyone else have this problem? If so, how do you cure it? Am I the only one with fuel caps that have tubes as vents?

Same here. I do not leave fuel in wing tanks for extended periods of time.

[M Towsley]

Re: fuel caps and escaping fuel

The caps you have are correct. I had an L-2 and always topped off the wing tanks when finished flying. I never noticed fuel loss. The vents are to pressurize the system to help feed the header tank behind the instrument panel. As you would have to vent the tanks one way or another due to fuel expanding and contracting the only way you could get away from this is to empty the tanks after you fly. Then you run the risk of the tanks rusting, though I am unsure as to what your tanks are made of. I would be leery of putting on non-venting caps while stored, perhaps someone else has had luck at this.

Are you losing fuel somewhere else, perhaps a bad cap gasket, while you are flying. Do you have streaks behind either cap? The evaporation loss should be negligible while just sitting.

Perhaps someone is stealing your fuel????

[M Towsley]

Re: fuel caps and escaping fuel

Same here. I do not leave fuel in wing tanks for extended periods of time.

Jim,

The L-2's main tanks are the wing tanks. There are the two 6 gallon wing tanks feeding a 2 gallon header tank behind the instrument panel for 14 gallons of total fuel on-board. Leaving them empty or draining after every flight would be a pain.

[PA1195]

Re: fuel caps and escaping fuel

I temporarily install these (examples only: http://www.ebay.com/itm/like/2619874...&ul_noapp=true) with a small #40 hole drilled in the end of each over both of my wing cap vents when parked only. Mainly to keep snow, rain, or bugs out and any volatile vapors from escaping in great quantity. BC12 with two wing tanks and interconnected vent system. I remove them prior to flight.

Venting of bulk storage tanks and loss of fuel has been documented over several months of storage. Don't know about small tanks.

If theft is suspected try what I used to do when flying to locations where theft was possible...slightly turn from closed each cap. Most thieves will drain the tank and fully close the caps in a hurry to be done. Same for those that would drop contaminants into the fuel. Yes there are folks that have done that and the fully closed caps were my alert to check the level and look for water or whatever.

Gary

[M Towsley]

Re: fuel caps and escaping fuel

Back in the day, 1940's, they would store the planes upended on their nose in the hangar to save space, using a sealed cap on the tank. (I am not sure how they did this, but my mother remembers this is how they did it at Stevens College in Columbia, MO). Probably Aeronca Chiefs as that is what they mostly flew along with some Luscombes.

Neither her nor her instructor saw the cap and ended up with an engine-out over the field. She remembers that well.

Again, I never had that kind of evaporation from my L-2. Sorry for the slight hijack with the above info.

[Guest]

Re: fuel caps and escaping fuel

Back in the day, 1940's, they would store the planes upended on their nose in the hangar to save space, using a sealed cap on the tank. (I am not sure how they did this, but my mother remembers this is how they did it at Stevens College in Columbia, MO). Probably Aeronca Chiefs as that is what they mostly flew along with some Luscombes.

Neither her nor her instructor saw the cap and ended up with an engine-out over the field. She remembers that well.

Again, I never had that kind of evaporation from my L-2. Sorry for the slight hijack with the above info.

ah!

I forgot all about those!

When I lived near Danbury,CT in the 60's there was an airport nearby in Stormville, NY that used Cubs for trainers and I recall flying in there and seeing them stacked on there noses.

Google Cub Stacker

http://www.j3-cub.com/forum/showthread.php?t=15207

Dave

[N63045]

Re: fuel caps and escaping fuel

Thanks for the feedback guys. Theft is not an issue, the airplane is in my hangar which is kept locked.

I am puzzled as to why Marty, who had an L2 with similar caps, had no fuel loss and I do. It is possible that the gaskets on the caps are bad. I am considering using these: https://www.aircraftspruce.com/catal...anesights3.php

[flyguy]

Re: fuel caps and escaping fuel

I would find a full wing tank would be down a gallon or so when I came down from flying with that tank full before takeoff and not used during the flight. Apparently the cap seal was bad just as you suggested. I stopped loosing a gallon of fuel each time that happened after I put in a new seal.
This was on a 12D.
Darryl

[M Towsley]

Re: fuel caps and escaping fuel

Your link is to a pitot cover. If you want a suggestion for a gas cap gasket hang on for a few and I will try and find out the ones I got. They are good for Mogas or 100LL and work very well.

If you think your gaskets are good, your caps tabs may be bent and not allowing the tank cap to pull down far enough. If your caps are originals that is over 70 years of service.

[M Towsley]

Re: fuel caps and escaping fuel

The only receipts I could find was from the company who originally made the gas caps for our airplanes, (they are still in business). Unfortunately, they stopped making the caps but are still providing the gaskets. I think the gaskets are Buna N rubber gaskets, you would have to check with them to see if they are good for Mogas and 100LL. I replaced mine with some white gaskets but cannot find the receipt for them. I will continue to look.

The part number for the gasket for the CA-1126 cap, (the original T-Craft fuel cap), is 1110.

Caps & Necks link: http://www.capsnecks.com/gaskets/index.htm

[flyguy]

Re: fuel caps and escaping fuel

Oh yeah, like Marty says, I also had a loose cap that I had to tighten up.
DC

[M Towsley]

Re: fuel caps and escaping fuel

Tony,

I looked through my receipts four times and cannot find the receipt for the white-colored rubber gaskets. It could be that Caps & Necks sent those to me at my request when I purchased the caps, (it has been several years). Check with them and see what they say. Hope this helps. Good luck!

[Guest]

Re: fuel caps and escaping fuel

does this help?

http://www.univair.com/search.php?search_query=gas+cap+gasket

http://www.univair.com/categories/hardware/gaskets-o-rings/miscellaneous-gaskets-o-rings.html

https://www.wagaero.com/catalogsearch/result/?cat=&q=fuel+cap+gasket

[astjp2]

Re: fuel caps and escaping fuel

Reeves and Stoddards have them on the shelf in Anchorage. Tim