billy's plans built sonex 1735

[sonex892.]

Hi Billy. With a new welded tank, if it failed the test and had a leak, I would repair by welding.

If a welder wasn't available, I see no reason pro seal couldn't be applied externally at the leak site. Thats what you would do with a prosealed tank if it failed the test. Iv'e never heard of issues with proseal other than it stinks and is messy and horrible to use. However here are many stories of sloshing compound sealant failing, normally due to alcohol in the fuel.

[Rofomoto]

Hi Billy. With a new welded tank, if it failed the test and had a leak, I would repair by welding.

If a welder wasn't available, I see no reason pro seal couldn't be applied externally at the leak site. Thats what you would do with a prosealed tank if it failed the test. Iv'e never heard of issues with proseal other than it stinks and is messy and horrible to use. However here are many stories of sloshing compound sealant failing, normally due to alcohol in the fuel.

So what you’re saying is if my welded tank doesn’t leak now I shouldn’t use pro seal? Maybe just around exterior seams only.. is this correct. Thanx agayfor all the help. Billy

[Bryan Cotton]

Billy,
With a good weld job and no leaks there is no need for pro-seal.

[Rofomoto]

Yeah!!! Just what I wanted to hear. Thanx all

[GraemeSmith]

Hi Billy. With a new welded tank, if it failed the test and had a leak, I would repair by welding.

If a welder wasn't available, I see no reason pro seal couldn't be applied externally at the leak site. Thats what you would do with a prosealed tank if it failed the test. Iv'e never heard of issues with proseal other than it stinks and is messy and horrible to use. However here are many stories of sloshing compound sealant failing, normally due to alcohol in the fuel.

So what you’re saying is if my welded tank doesn’t leak now I shouldn’t use pro seal? Maybe just around exterior seams only.. is this correct. Thanx agayfor all the help. Billy

Page 2 of the tank installation sheet.

https://www.sonexaircraft.com/documents ... nstall.pdf

Specifically advocates against the use of sealing compounds. At least INSIDE the tank. In at least two places in the document.

It also sets a maximum tank test pressure of 5psi. Over 5 voids the warranty.

--

Pro-Seal's Tech Sheet

https://www.aircraftspruce.com/catalog/ ... chData.pdf

also states:

"Substrate composition can vary greatly. This can
affect sealant adhesion. It is recommended that
adhesion characteristics to a specific substrate be
determined prior to application on production parts
or assemblies"

--

I'd be VERY leery of expecting anything to stick to a polyethylene tank for any period - inside or out. Inside it seems to be a guarantee of introducing debris into the fuel system. Or if applies externally - the "patch" just falling off or leaking in due course.

YMMV

[Area 51%]

Hi Billy.

The guy who welded my tank was used to testing marine fuel tanks with 5psi. They were, however, made from .125 material. He did test my tank at 5psi and reported no ill effects to the structure other than it was noisy with all the oil-canning. Oh yeah...It spit the fuel cap about 10ft.

It probably helped confirm the integrity of the welds.

[racaldwell]

I can verify that proseal can fix pinhole weld leaks. Over some years, I had some pinhole weld leaks on the joints of my One Design AL tank. First time I had Steen Aerolab reweld that location but then another leak returned. I prosealed the length of that edge and put an 3/4" x 0.025 AL angle over the proseal. That worked. A year later another seam started leaking so I then did all the straight seams. Never leaked again for the next 6 yrs I had it.

My Xenos tank Oops fitting install was a disaster. I ended up making AL sheet backings for the protruding area where the fittings are located and prosealed between the plastic tank and the AL sheets and used the Oops fittings to squeeze it all together. This has held 100LL for a year now with no leaks. I am just now making the fuel system and have a separate support for the fuel shut off valve so there is no weight or stress on the fuel tank fittings. Also put the valve where I can reach it.

Rick Caldwell
Xenos 0057

[Rofomoto]

I can verify that proseal can fix pinhole weld leaks. Over some years, I had some pinhole weld leaks on the joints of my One Design AL tank. First time I had Steen Aerolab reweld that location but then another leak returned. I prosealed the length of that edge and put an 3/4" x 0.025 AL angle over the proseal. That worked. A year later another seam started leaking so I then did all the straight seams. Never leaked again for the next 6 yrs I had it.


Rick Caldwell
Xenos 0057

Thanx Rick. So you just laid the aluminum angle over the seams on top of the proseal and the proseal holds it on?

[racaldwell]

Billy, Yes. The proseal was put on thick enough so the weld bead is completely sealed and the excess proseal was wiped away at the edges of the angle. When cured, proseal is a great glue. It needs to cure at least a week before fuel is added back into the tank. The angle with its radiused corner gave a smoother surface on my legs than the jagged weld bead before I did this. The lower tank in the One Design, just like a Pitts, is right between your lower legs

Rick Caldwell
Xenos 0057

[Rofomoto]

Thanx Rick thinking I’ll do this right away before installing it.