Ratty 'round the gas cap

[mhorowit]

How should the gasoline filler neck for the wing tank pass thru the fabric?
On mine, there is a 1/4" gap between the filler neck and the fabric and the fabric appears to have simply been cut out. and it's looking a bit ratty.

Seems someone earlier stated there should not be a gap, so I'm wondering what's the smart way to improve this condition?

[paulp]

Re: Ratty 'round the gas cap

Howdy Mike,

There should be a round fairing that fits closely aroung the neck and is then glued into the fabric. The ring itself, is about 6" in diameter with a 3" hole in the center for the gas filler neck. You can make one out of .016 alum. but the 3" portion is flanged downward. It's a little tricky but you can do it.

[Robert Lees]

Re: Ratty 'round the gas cap

These rings are perforated (like the aileron cove) to allow a larger fabric bonded area. As Paul says, the inner diameter is "dished" (like lightening holes) to stiffen it.

While on the subject of tank filler necks, the fabric should be sealed against the neck so as to prevent spilled fuel from getting inside the wings. A rotten rear spar will be the result.

Here's the tank reinforcing ring.

Outside diameter is 4 and 3/16 approx
Inside diameter is 2 and 5/16 approx to match filler neck diameter.
Depth of recess is 3/8" approx
Eight holes 1/2" diameter through which to bond fabric.

The second photo shows the result. Note the fabric up the side of the filler neck to prevent fuel spillage ingress into the wing (I have longer filler necks than standard...see here for explanation).

Rob

[mhorowit]

Re: Ratty 'round the gas cap

Howdy Mike,

... and is then glued into the fabric. ...... the 3" portion is flanged downward. It's a little tricky but you can do it.

1. 'glued into the fabric' - am I correct this means removing dope down to the silver, gluing the flange into position, then gluing fabric over the flange?

2. 'flanged downward' - any idea why 'down' is better than 'up'? I would think 'up' would provide a foundation for the fabric wrapped around the filler tube- MIke

[paulp]

Re: Ratty 'round the gas cap

Mike,

It is flanged downward in order for the gas cap to fit more closely to the wing surface.

Rob is ceartainly correct in that the gas filler neck and the flange need to be sealed. You don't want raw fuel running inside the wing as it WILL collect at the rear spar.

[mhorowit]

Re: Ratty 'round the gas cap

Paul - just to make sure, please see attached pic. That's what you mean, right?

[paulp]

Re: Ratty 'round the gas cap

Mike,

That's it!!! Rob, in his own inimatable style, has just posted a couple of excellent examples. Those little buggers are hard to come by but they are very necessary.

Rob, if you see this, have you attempted to mfg any of these rings? I tried once and failed miseraibly!

Good luck Mike. Worst case sceinero, call St Louis Metal Arts. I think they have an ad on Barnstormers.