I wasn’t present when the fuel cap installation began. When I saw how they were installed, I wasn’t nuts about them but I wasn’t certain that they were not… optimal and didn’t want to make a stink about it. Besides, I figured it would be a real pain to fix anyway. But after looking at planes at Sun-n-Fun and Oshkosh, I knew something had to be done.

Here’s what the fuel caps look like.

I wanted a flush installation. I think part of the problem was that these fuel caps aren’t the ones that come from the factory. Those were kind of cheap looking with a fair amount of plastic. So I found a company that makes fuel cell caps for race cars. No plastic, all metal, very high quality.

The first order of business was to cut out the cap. I first cut out just the cap itself. But then I realized that I would need to put a backing plate inside. So I cut the hole into an oval.

Here’s the hole with the backing plate.

Then I cut a hole into the backing plate and put on a couple coats of Jeffco (fuel resistant epoxy). Once it was dry I mixed up some more Jeffco and added some Cab-o-sil (thickener) and spread it around the edges. Then I put the backing plate inside the fuel tank and pulled it up against the inside of the tank.

Now I had to make a mounting flange. So I clamped the fuel cap collar to a piece of 1/4″ aluminum stock.

Drilled (and tapped) the holes for the collar.

Then I marked the center for the BAH (Big Assed Hole).

Then I used a hole saw to drill the BAH.

Finally I cut out the outside. My 15 year old jig saw really wasn’t up to the task. But the outside cut wasn’t critical.

Then using Jeffco with cab-o-sil to thicken it, I secured the flange in place.

The next step was to cover the screw holes with some duct tape. (Here I’ve done all but one) Then fill in any voids with thick Jeffco and cover the whole thing with fiberglass.

Then I cut out the holes, plopped some some thick Jeffco down the screwed down the collar to the mounting flange. Once it cured, I filled and sanded the surrounding area:

Much better.