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Tank repair Q.

az_gila

az_gila

Well Known Member
After 18 hrs I have the start of the "dreaded blue stains" from the right tank upper baffle. :(

I have Vans repair kit and now have 5 large holes in the rear baffle. I have started scraping away the somewhat marginal proseal fillet along the rear baffle, fiddly work but quite doable.

My real question is "what tool do I use to add a new fillet?" Since it's essentially in a blind location and mirrors are needed my usual popsicle tool or SEM air powered dispenser won't work.

How have others got their goop into place?

I intend to remove as much of the existing skin/baffle proseal and hen use adhesion promoter under the new proseal. Since it will be 85 F plus in the afternoon in the hangar the proseal should flow fairly well. :)

Some things I found out already that might help others -

1. 5 inch holes are easily cut with a m Milwaukee hole saw from the local Ace store. The manager said it's probably the only one he's sold of that size. :)

2. The part of my Pepto-Bismol cowling that was cut away for the oil door makes a great proseal scraper.
 
I like using a pneumatic sealant gun and the 2-oz cartridge. (about $20 for sealant from Aircraft Spruce) The pistol grip is held on with a quarter turn fastener. It is possible to discount the pistol grip, slide it down the hose, then use it as an inline calking gun. May be able to do that and use a mirror to see where it needs to be applied.

I did the above to get some fillets inside near the nose ribs and skin on my RV-8 tanks before putting on the rear baffle. Worked much better than with the pistol grip on.https://encrypted-tbn0.gstatic.com/images?
 
Gary, I can't see your picture...

I do have access to a pneumatic sealant gun and some 'load it yourself' cartridges. I think the problem is that I would need a U shaped extension to get through the 5 inch hole and back onto the skin/baffle joint.

I think getting an extension to stay in place under pressure will be tricky. I've tried it with standard RTV caulking guns and mainly succeeded in making a mess. A similar proseal mess would be bad. :eek:
 
might try a big 'horse' or catheter syringe. i think they might be small enough to get your hand in and apply. Used them a lot when building my tanks, they will lay a nice bead down.

I used 60 ml but even 20s could work.
 
2-oz pneumatic sealant gun

Here is what a 2-oz pneumatic sealant cartridge gun looks like.
2017-09-05_08.58.20.jpg


The handle removes by turning a 1/4 screw.
2017-09-05_08.58.33.jpg


With the handle off, it looks like this.
2017-09-05_08.59.04.jpg


With a short nozzle that comes with the sealant cartrige, it is short enough to fit inside the tank. Shown here laying on the RV-8 tank I sealed last week.
2017-09-05_08.59.51.jpg


I used these 2-oz sealant cartridges.
 
Tank repair

Gil. I have both of my tanks out repairing for leaks.
A huge help is to get ahold of the lower viscosity proseal or figure
Out a way to thin out the thicker product. Lower viscosity will find its way
To a better seal for existing built tanks. If you figure a way to thin it out please let us know. In my opinion it's a much better way to go. I was able to apply a bit of air pressure to blow it into the repair area.
 
I used my finger with a thick latex glove. Dip, insert, spread, repeat. I changed gloves every few cycles.
 
pa38112 said:
I used my finger with a thick latex glove. Dip, insert, spread, repeat. I changed gloves every few cycles.
Click to expand...

I'm moving towards that method, but for making the fillet.

I borrowed a Semco dispenser and some load-it-yourself 2 oz and 6 oz cartridges. We had 4 inch tips and it looks like a heat gun can give these an almost 90 degree bend. With this bend the gun can be kept outside while the goop is dispensed along the baffle/skin interface through the large 5 inch baffle holes.

Then the gloved finger can make the fillet and force the stuff into the angle and I will then set the tank at a 45 degree angle so any stuff that flows/sags will go in the correct direction. :)
 
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The fickle finger of fate

I used mine to smear proseal on a small leak in the bottom baffle seal. Was on both sides of a rib and after I cut the access holes I couldn't get anything in there by way of Popsicle sticks or applicators. So I put on a glove, scooped up a pretty good glob of proseal and got it as close as I could with my finger. Unthinned proseal will flow for a couple hours before it sets; albeit very slowly. So I put a glob on one side of the rib and tilted the tank so the sealant would flow toward the seep. Couple days later same thing on the other side. That was 3 years ago and still good. Hope this helps.
 
Flamemaster makes a one part pourable sealant that's compatible with their regular 'proseal'. It can be drawn into a flexible plastic tube & directed where you need it. With care, you can run the entire top or bottom seam with it, from one end of the tank.
 
rv7charlie said:
Flamemaster makes a one part pourable sealant that's compatible with their regular 'proseal'. It can be drawn into a flexible plastic tube & directed where you need it. With care, you can run the entire top or bottom seam with it, from one end of the tank.
Click to expand...

That almost sounds like the white slosh that I had previously spent many stinky days using MEK to remove. That was done before the rear baffle was installed.
 
Nope. It's red.

Seriously, the slosh issue is another discussion, and more complicated than the slosh itself, too.
 
agirard7a said:
Gil. I have both of my tanks out repairing for leaks.
A huge help is to get ahold of the lower viscosity proseal or figure
Out a way to thin out the thicker product. Lower viscosity will find its way
To a better seal for existing built tanks. If you figure a way to thin it out please let us know. In my opinion it's a much better way to go. I was able to apply a bit of air pressure to blow it into the repair area.
Click to expand...

The lower viscosity is the A instead of the B in the spec number. Aircraft Spruce has it.
 
az_gila said:
If it's this one, it looks to be more of a top coat (and an adhesive if you can separate the parts) than a product that can make a corner fillet.

http://flamemaster.com/wp-content/uploads/2014/07/CS3600.pdf

The data sheet mentions a 1 mill thickness.
Click to expand...

That's the stuff. You're right about what the data sheet says, but it's also what they recommended in a phone conversation when I described improperly sealed seams (top & bottom edges of the back baffle) that had been sealed with their polysulfide product. I suspect that the last sentence of the 1st paragraph covers that:
"CS 3600 is also used as a top coat for polysulfide sealants in
integral fuel tanks for aircraft."

I can't think of a reason to topcoat polysulfide inside a fuel tank, unless you're fixing a leak.

Charlie
 
Tank seal

When I removed white slosh I replaced with pro seal I used gloved finger ,Popsicle stick, and or ziplock bag with small hole in it to place pro seal where I needed
 
Tank Repair

I had a couple leaks develop as well. Used my Mark 1 Finger with disposable gloves...You can feel the application and check with mirror. No leaks and really no mess. You can get like 300 gloves for $10 buck...
 
Berchmans said:
I had a couple leaks develop as well. Used my Mark 1 Finger with disposable gloves...You can feel the application and check with mirror. No leaks and really no mess. You can get like 300 gloves for $10 buck...
Click to expand...

Yes... I'm moving that way. I think I'll dispense it with the bent nozzle on the Semco gun, and then 'finger' it into place.

Off to buy new gloves tonight, the ones in the old box sort of rotted in the AZ heat.
 
az_gila said:
Yes... I'm moving that way. I think I'll dispense it with the bent nozzle on the Semco gun, and then 'finger' it into place.

Off to buy new gloves tonight, the ones in the old box sort of rotted in the AZ heat.
Click to expand...

Gil - MEK or Acetone is a recommended cleaner for Proseal. Sparingly, a small amount of MEK on the glove finger allowed me to form a nice filet without the Proseal "gumming up" and sticking to the glove. A very slight film of MEK seems to be all it takes. I did this for my tank build, not a repair, but same principles apply.
 
JonJay said:
Gil - MEK or Acetone is a recommended cleaner for Proseal. Sparingly, a small amount of MEK on the glove finger allowed me to form a nice filet without the Proseal "gumming up" and sticking to the glove. A very slight film of MEK seems to be all it takes. I did this for my tank build, not a repair, but same principles apply.
Click to expand...

I'll try that. I even have an old gallon of MEK I bought before it became unavailable and only "MEK Substitute" is now sold.

I also have a remote air breathing system that helps with the yucky smells...:)
 
Water is also a good substitute to avoid sticking to the finger while forming a fillet. Applying Proseal with the gun, waiting 15-30 minutes and smooting it out to a fillet using a damp finger works like a charm. In your case, working blind in a confined space is the biggest challenge which I'm not sure how it works. We used the above technique to form a nice fillet when sealing inside corners and edges with Semkit ploysulphide sealent (basically same as tank sealant stuff) around cupola and hatch assemblies of armored vehicles.
 
ProSeal application

Gil, I just finished sealing both tanks. I used a large syringe and scooped in proseal.
These were new tanks. Layed in great, looked perfect yet failed leak test. I then cut 4" holes in the aft. put on laytex gloves and finger dipped and smeared good fillets. You'll be working blind just like tightening bolts on an engine. After letting set overnight I inspected with a bore scope I picked up at the parts store. There was a few places that needed another dose. I wouldn't thin proseal unless you check with vans or manufacturer, as cross link of polymers will be compromised. Not worth the chance. Tanks passed.
 
MEK works, but I *IIRC*, the Flamemaster docs say to use Toluene. At any rate, it's in the docs, so easy to see for yourself.
 
I used MEK only as a release agent so the pro seal wouldn't stick and ball up on the glove finger. None was mixed into the proseal.
 
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