Tip: Proseal ...The fact and the fiction

[Av8torTom]

Just finished my right fuel tank using the fay method that Rick described. Much easier and neater than the left tank which I did following the manual. I 100% clecoed everything Friday, then riveted today (Sunday). The weather has been cool so by today the proseal I used on Friday was like soft tar. I used a toothpick to push the little "nit" of proseal out of the hole, then used another toothpick to dab some fresh proseal in the dimple before riveting. MUCH neater and MUCH less stressful way of sealing and riveting the tank. Most importantly, you can visualize the shop head of the rivet MUCH better with this technique.

Filling the dimple with a little dab of fresh proseal


This method allows for a very neat job




P.S. - what looks like streaks of Proseal on the tank skin in the last picture is the reflection of the rib's lower flange

Thanks Rick.

[jjet]

An IA I know that works with Mooneys helped me with a small seam leak in the back of my tank. He said rather than cut a hole and fill from inside, you could suck proseal into crack. He talked to the company that produces it and they said you can thin proseal with Toulene since it is soluble in toulene. Ironic part of this is is that Toulene is what keeps the blue dye in suspension in 100LL. Once proseal is set up, it's ok, but if it isn't completely set when you add fuel, you're going to have problems.

Anyway, here's what I did.
1. Sealed off tank except for vent tube and put a shop vac hose in filler hole. I left the vent tube open to avoid pulling too much suction and damaging tank.

2. Cleaned area of leak with MEK and used vac to suck some MEK into leak and let it evaporate.

3. Mixed up some proseal and thinned to consistency of about Karo syrup or some of that running "natural peanut butter".

4. Put the proseal on and used shop vac to suck it into leak. I let that cure for a few days and leak checked and it was good.

5. To be extra sure put more proseal on outside. I know a few tanks that have been done this way with small leaks on seams and none have failed to date. One has been about 4 years.

I actually have a photo from inside tank that shows where the proseal streamed back along bulkhead.

jjet

[coldbearsteve]

Just finished my first tank( right ), and leak tested. No bubbles. Have had balloon on vent for over 48 hours and balloon is still inflated!

Thanks so much to Rick for sharing this method. I had been reluctant to start the sealing process till I read Rick's post. Can honestly say it was fun.

Steve

[Travelair]

Rick's original post in this thread refers to "handy device, essentially a caulking gun" but the tiny url link is broken. Would someone please post/describe which caulking gun device he was recommending?

[rvbuilder2002]

Originally Posted by Travelair

Rick's original post in this thread refers to "handy device, essentially a caulking gun" but the tiny url link is broken. Would someone please post/describe which caulking gun device he was recommending?

Not sure if it is the same one he was linking to, but HERE is a calking gun meant for use with Sem kit sealant cartridges.

[nineninefour]

Forgive my inexperience, but why would one not back rivet ribs to one side of the skin from the inside, before wrapping the skin? It seems that this would be easier and faster.

[longranger]

Originally Posted by nineninefour

Forgive my inexperience, but why would one not back rivet ribs to one side of the skin from the inside, before wrapping the skin? It seems that this would be easier and faster.

One reason is that you wouldn't be able to shoot and buck solo. Since you wouldn't be able to use a flat backriveting plate on the curves of the ribs, and it would be next to impossible to control an offset backrivet set solo, you'd need someone on the outside with a bucking bar - and maybe a third to hold the skin open for you...

Another (and maybe more pressing) reason would be the difficulty of clecoing the second side of the skin to the ribs after you've riveted one side. It's difficult enough dry; I can't imagine what it would be like with sealant slathered all over the parts. The instructions have you dry cleco all the ribs into the skin then remove one at a time for sealing, letting the others hold the shape.

Sealing the tanks is not really as bad as many make it out to be. For me the worst part is measuring and mixing, but even that is OK once you've worked out a process. I did my first tank solo with reasonable results, and only minor cleanup. I'm in process on the second, and plan to do it the same. One thing I've found that I didn't see here or any builders' logs is to wipe the outside of the rivet of sealant before setting it; it greatly improves (for me at least) the flushness of the finished rivet.

[SilverEagle2]

I used Ricks method for the first half (ribs to skins) and I must say...all my fears of ProSeal really were for nothing. This is pretty clean way to get the bulk of the sealant done on the tanks.

I hope to have both tanks riveted during this week sometime. Wish I had done it sooner! Thanks Rick!

[rmartingt]

Originally Posted by SilverEagle2

I used Ricks method for the first half (ribs to skins) and I must say...all my fears of ProSeal really were for nothing. This is pretty clean way to get the bulk of the sealant done on the tanks.

I hope to have both tanks riveted during this week sometime. Wish I had done it sooner! Thanks Rick!

How many clecoes did you need to do that? I'd like to lay all the ribs in at once but I don't know if I have enough clecoes to be able to fill every hole on the interior ribs...

[SilverEagle2]

Originally Posted by rmartingt

How many clecoes did you need to do that? I'd like to lay all the ribs in at once but I don't know if I have enough clecoes to be able to fill every hole on the interior ribs...

340 total will take care of both RV-7 tanks!

I had to borrow some from a buddy to make it work and still leave my top skins and leading edges together.