To gasket or not

With only the access plates and float senders left,I need some advice.i know this has been discussed before but i'm thinking about just sealing the covers on and not using the cork gaskets.also, why does vans say not to use the rubber gasket under the float sender plates? I'll be really glad when I can move on from the tanks,not a bad job,just a really messy one.thanks for the advice, Dave

Cork and seal

I would use the cork gasket and proseal front and back as well as all around for a tight seal.
In my experience I had to open the tank access plates once to comply with
a SB concerning the fuel pick up tube that had in some installations rotated out of position and failed to pick up the bottom 5 gallons of fuel or so.
What I remember about having to cut open the access plate was that cutting the cork part was much easier than trying to cut through proseal.
The cork gasket will be toast anyway and inexpensive to replace.
So, a bead of proseal on the tank side and around screw holes, apply cork gasket and the same proseal application on the cover plate side. Screw it shut and apply a small bead around the matting surface as well as cover the screw heads in proseal. I built 4 tanks for 2 airplanes and have never had a leak.
I cannot remember what I did with the sender unit and I don't recall Van saying anything about not using the rubber gasket.

I just prosealed on the access plate. No gasket.

Toss the Gasket

Throw the gasket away and use only Pro-Seal.

You can open it up with just Pro-Seal and the Pro-Seal will not leak over time. I have seen too many cork gaskets leak over time. If you use cork, at some point in the future you WILL be taking things apart to fix a leak. If you only use Pro-Seal, it can still come apart and has a much better chance of not leaking at some point in the future.

It was over 20-years ago that I took the rear tank close out off the back of both RV-4 tanks that had been flying and started to leak. Both close out baffles and the tank were reused without damage after repairing the fuel tank.

What Gary says. I started with cork and it is all gone now after having to repair leaks.

I used the cork gasket and no leaks in 5.5 years. I also used the hex-head bolts rather than standard screws. Makes it easier to tighten in place if needed. Just another data point.

Greg

As a guy who has been supporting the maintenance of a dozen RV's over 12 years. The best answer is no gasket.

FYI, another point of view: I have built 2 7As, an 8A, 9A and a 10. Ten tanks total. I used cork gaskets with #3 Permatex on all covers and senders. I have never had a leak. It also makes removal very simple if it is ever necessary.

Be careful with proseal and no gasket

I just want to throw out a word of caution on going with proseal only on the tank access panel.

My plane is 10 years old now and I've had both tanks off several times every few years to seal a leaky cork gasket. I used cork and a lot of fuel-lube and cork and proseal on each sides, but they eventually always leaked. The last time, I decided enough was enough, and I read the threads about using proseal only, so that's what I did. I sealed the access panels using proseal, tightened down the screws, and put the tanks back on yet again. 2 years later, the tank is leaking (but not at the gasket, this time) so I need to get the cover off (or maybe not, more on that later).

I've now been working for 2 weeks trying to get the access panel open. I'm using poly-gone gel (which dissolves proseal very effectively) but I still can't get the proseal to let loose. Probably because the layer is so thin because I tightened the screws when the proseal was wet. I can't get ANYTHING between the tank rib and the access cover. (not a scraper, not a plastic knife, not even dental floss.)

I would not recommend this **** to anyone.

I have already cut one (several more to go) access panels into the back baffle and I'm even working at it from the inside too.

At this rate, I might just leave it alone and instead create a removable panel in the back baffle in the first bay.

I now found a different kind of proseal that is "less sticky" and can be used for removable panels. That is what should have been used here... not the "real stuff" that is used to seal the tank.

The more I look at this I wonder why there is an access panel on the inside rib at all. It seems to me the best spot might just be the back baffle and use a solid inside rib instead. (I'll post more on this idea in a separate thread)

So, beware. Don't use normal proseal on anything you ever want to remove without destroying.