fuel tank inspection plate sealant

[bobnoffs]

hi all,
i have built a tank for my 12 and i have the inspection plate op the top surface. it was recommended to me that permashield #85420 would provide a fuelproof seal and be easily removeable. while fuel testing on a bench the plate leaked so i removed it and drained the tank.on the floor of the tank was a goo, looked just like honey, under the area the plate was over. i had doubts about this stuff when i put it on. comes out of the tube with very uneven consistancy, watery to thick even after trying to squeeze tube to mix it. instructions say to let stand until solvent evaporates .what the heck does that mean? i just now took some and squeezed it out in a jar of gas. within an hour the blue tint had leeched out of the product and into the fuel but the product looked white, not like honey.
so maybe i didn't use product correctly but i don't think i want to try it again and close tank up for good with thoughts of more goo in my tank.
besides proseal any recommendations for something that will allow the plate to be removed when necessary?
thanks in advance.

[rv7charlie]

Hi Bob,

It was likely me that recommended the product. I'm a bit mystified at your symptoms. I've used it for several years on my RV-4 tank inspection covers. I've been back into one of them several times (I keep having more proseal leaks), and the 'squeeze out' inside the tank is always bright blue, as it comes out of the tube. Note that I run E-free premium mogas, except when away from home and I'm forced to buy avgas. I wouldn't expect E-gas to affect it, but I haven't tested it with E-gas in my tanks (still have an old engine driven fuel pump that E-gas will kill).

My interpretation of 'let it stand until the solvent evaporates' has been the same as it would be if you were using many contact type adhesives. Having said that, I've never had an issue with it leaking as long as both surfaces are clean, I spread it on both surfaces, and by the time I finish the 2nd surface I figure I've given it time to flash off.

My only wild guesses about your problems would be inadequate surface prep (cleanliness), poor mating quality between the surfaces (it's not a 'filler', like proseal is), or maybe even a bad batch of sealant. I do see the same 'inconsistent consistency' coming out of the tube, but by making sure I get coverage from the toothpaste consistency stuff and don't depend on the watery stuff (which I've assumed to be primarily the solvent), I've had great results. To repeat, I do apply to both surfaces, like you'd treat a contact cement, prior to mating up the cover to the flange.

No idea why you're seeing what you're seeing, and I'm really sorry it hasn't worked out for you. It might be worth a call to Permatex. I've called them in the past, and they have been very responsive to questions about their products.

Charlie

[9GT]

Originally Posted by bobnoffs

besides proseal any recommendations for something that will allow the plate to be removed when necessary?
thanks in advance.

You can easily pop off an inspection cover that is installed with Flame Master tank sealant (pro-seal) using a little heat from a heat gun and a stiff putty knife. Remove the sealant completely with a good epoxy rated paint stripper.

[David Paule]

There's a tank sealant, Pro Seal-like, meets the appropriate specs, called "Access Hatch Sealant." I got some from Skygeek.com. It's intended for exactly this application.

At Skygeek, do a search for it and it'll pop right up.

Mixed, it's a dirty pink in color. Odd.

Type A is a syrup consistency, handy for edges and dotting rivets and screws. Type B is the thick stuff we're used to. The -2 means, I think, a 2 hour pot life, while the -1/2 is only half an hour. This paragraph, by the way, applies to regular tank sealant too.

Dave

[scsmith]

Permatex "high tack" or Permatex "Aviation Form-a-gasket" Neither one has ever let me down on exactly this type of application. It is what I have on my RV-8 tank access covers, AND using the supplied cork gaskets. (3 of them because I have a flop-tube mounted in one tank with an access cover in the rear baffle.)

I have easily removed each of my wing root-rib covers once because a fuel sender issue necessitated it. Cleaned them up with some acetone, replaced the cork gasket and re-sealed them with more High Tack and never had a problem.

Good luck getting a heat gun in there to soften Pro-Seal with the wing on the fuselage!

[lr172]

The problem with the inspection plates is that the rib skin is thin and the screws are spaced too far apart to put a lot of pressure on gasket. I would use something that grips (i.e. adheres), like pro-seal or others.

I used an anaerobic on the senders, but didn't feel that would work on the large plate for the reasons above.

Larry

[Maxrate]

Bob,
Here?s what I used. After leak testing for 72 hrs. In a climate controlled environment there was no leak noted.

http://websites.expercraft.com/markm...y&log_id=74616

[bobnoffs]

i think i am going with the product from sky geek. getting the plate off easily is important to me and the sky geek stuff falls between gel shoe insoles and rubber bands on the ''hardness chart'' when cured. i think i can lay down a thick coat like van's recommends with proseal and keep it thick by cautious tightening of the screws. downside of this stuff is that it is 2 part and $18 plus shipping. makes it harder to follow thru with the plan to check finger strainers and sump often in the first year. but my fuel gauge is mounted in the middle of the plate and that mueller stuff seals well with their rubber gaskets. guess i will peek in the fuel gauge hole.
thanks for all the ideas.

[bobnoffs]

one last poke at permatex #85420 gasket dressing and sealant and i am done.
i thought maybe i hadn't let the product ''cure'' enough before i put the pieces together so i put a glob on a piece of paper and let it sit for a couple days. yesterday i put the paper in a jar of gasoline. today the blue color is totally gone and most of the product is gone. the small bit left looks is very runny and yellow.
i must have gotten a bad tube as others report success with this stuff but i am done with it.

[az_gila]

My Tiger has access panels directly into the integral fuel tanks. They use a 'low adhesion' sealer so future removal is possible.

FlameMaster CS3330B or Desoto/PRC PR1428B is recommended and is a red color.

https://www.aircraftspruce.com/catal...it09-04704.php

https://www.skygeek.com/flamemaster-...nt-1-2-pt.html