Proseal question... is this ok?
 

So yesterday I started prosealing the ribs in the tank. I got them riveted up, and put the fillet on 2 of the ribs... and ran out of the batch I mixed up. I was so a$$-whipped (please God, dont let this thing leak!) by this stuff at that point that I called it quits for the day. My question is this... is it ok to wait a day or two before I go back and put a fillet on each rib and then a dab on each rivet head? Or is there some reason this has to all be done at the same time? Also, on the end rib, I didnt really do the dab on each rivet head... but instead smeared a thick layer in all directions with my finger to cover everything. I was thinking about doing this to all the ribs... Will this provide enough seal or should I go back and put the dab on each? Here is a pic of what I'm talking about:

proseal
 

Daniel,

Make sure each and every rivet is well dipped in Proseal and then the shop head well covered. Better to fillet when installing, but you can do it later as well.

For the end ribs, the fillet is more critical than the dabbing, given the shop heads are outside the tank. According to your photo, I would say what you did on the shop heads is fine, but it's the fillet that really matters here.

You really want to avoid any rivets leaking once that rear baffle is on. Mind you before installing the baffle, you may want to test by filling with water. I mangaged to pick up and correct two rivets leaking this way.

Once the rear baffle is installed, should you discover a leaking rivet, you may correct by using blue locktite and a vaccuum cleaner to create suction and draw the locktite inside the tank. Proseal diluted with MEK, to make it more liquid, can also work here.

Good luck with the rest of the tanks,

regards,

Normand RV 8 Fuselage slow build.

Checking for gross leaks with water is OK, but don't depend on it. Gas is less dense than water and will leak through places that water won't.

So when the day comes that I am ready to put the rear baffle on... can I just buy enough avgas to fill the tank in the craddle and see if it leaks?

I think you're tanks will turn out just fine. I just finished mine, you can see the progress here:
http://moener.blogspot.com/

I wouldn't worry about the mess or risk of dealing with avgas. Just make sure you put a decent bead of sealant in front of the rivet line before you push the rear baffle on. It does indeed form a fillet. I have proof here

Also, don't worry about covering the shop heads of the two outside baffle or the rear baffle. If you form a nice fillet on the inside, the fuel will never reach those spots. (I did this on one side, and then realized it wasn't neccessary so I skiped it for the baffle and the other side.)

Just test the tank by presure testing it with air using a balloon, and if it holds, you're all set.

Not to much in front
 

Make sure the bead of sealant is nice and healthy and right along the front edge of the rivet line and not to far forward before you push in the rear baffle. On my first tank I was frightened by Vans instructions about using too much sealant to avoid "pillows" or something like that. It turned out my bead was just a tad too far forward and it didn't make a fillet against the rear baffle. What a nightmare that was to fix!

try a U tube manometer
 

I agree that you don't need (or want) to mess around with Avgas for leak testing, but I didn't get good balloon results. It was hard to get the balloon sealed well, and then when I did, it inflated and deflated by itself. It was due to the ambient temperature change in the shop.

A better, and more importantly easier, way was to look a long clear tube up to the tank, one end open, and filled partially with water. Make a U shape from the tank down and back up vertically. Mark the tube on the upward vertical side where the water falls when you pressurize your tank. You can then watch it move up and down (literally). After a couple of days you'll see that it moves up and down and isn't trending down. No leaks (I hope). BTW - the hardest thing was to seal the fuel filler cap and the tank test valve.

Good Luck - your tank looks great.

Build on - use plenty of proseal, leak test with a DIY-manometer, and seal the cap and drain with Fuel-Lube (EZTurn).

One thing I noticed with your photo (though it may just be my monitor or teh way the photo reproduced) is that the sealant looks very dark in color like it is quite a bit rich in catalyst.
The proper color is typically a medium gray. How are you measuring the material ratios. A little extra catalyst doesn't hurt but if you get carried away it does degrade the performance of the sealant and the working time is reduced.

Missing T-410 Reinf. Plate
 

Daniel,

I could be wrong, but it looks like this photo is of the ouboard tank rib. It also looks like you're missing the T-410 reinforcement plate on this rib (no holes/rivets). This plate would have covered the tooling hole that you've plugged with something else... pop rivet? You'll definately want this plate.