[llavalle]

I'm just about ready to start sealing my first tank on my -9A.

The instructions say that the only piece that should be primed is the attach angle that goes in the inboard leading edge : that had me thinking. If this is primed, the pro-seal will not stick.

1)Then I thought : do I need to seal the outside of the outboard ribs? I don't see any reasons to do that... The inside filet will prevent fuel from getting under the ribs. For the inside ribs, I get it : you do not want fuel getting in the rivet's hole and dripping out.

2)Same question for the AD6 rivet I just drove in the tooling hole : covering the inside should be enough?

3)While I'm at it, when I'll back rivet the stiffners in the tank, I won't cover the rivets with pro-seal. I'll put a nice layer on the stiffner, install and back rivet, make a nice filet and cover the rivet's head. For the ribs, do I need to add pro-seal to the rivet's before driving it?

Tomorrow (well, later today, it's 2 AM here ) will be my first sealing session with pro-seal and I want to get it right. I've only used it when I closed up the trailing edge of my empennage parts a couple of weeks ago.

Thanks!

 

[Robert M]

I'm just about ready to start sealing my first tank on my -9A.

The instructions say that the only piece that should be primed is the attach angle that goes in the inboard leading edge : that had me thinking. If this is primed, the pro-seal will not stick.

1)Then I thought : do I need to seal the outside of the outboard ribs? I don't see any reasons to do that... The inside filet will prevent fuel from getting under the ribs. For the inside ribs, I get it : you do not want fuel getting in the rivet's hole and dripping out.

2)Same question for the AD6 rivet I just drove in the tooling hole : covering the inside should be enough?

3)While I'm at it, when I'll back rivet the stiffners in the tank, I won't cover the rivets with pro-seal. I'll put a nice layer on the stiffner, install and back rivet, make a nice filet and cover the rivet's head. For the ribs, do I need to add pro-seal to the rivet's before driving it?

Tomorrow (well, later today, it's 2 AM here ) will be my first sealing session with pro-seal and I want to get it right. I've only used it when I closed up the trailing edge of my empennage parts a couple of weeks ago.

Thanks!

Question #1: Don't take the chance that the seal on the inside will be enough. If for some reason the pro seal doesn't adhere to the skin perfectly - on the inside - potential leak. Be sure to soak all of the rivets (including the AD6 rivet) in lacquer thinner or MEK before you use them so any manufacturing oils or residue is cleand off and swirl them in proseal before inserting them into the holes.


Question #2: You will want to put proseal on the inside, outside and through the hole on that rivet.

Question #3: When you back rivet the stiffeners into the tank, you will want to dip/swirl each rivet into some proseal when you place them in the holes. Again, be sure to soak all of the rivets (including the AD6 rivet) in lacquer thinner or MEK before you use them so any manufacturing oils or residue is cleand off.

Be generous with the proseal. I had a tank that leaked and that was a headache I don't want again. I learned from the first tank when I built the second.

 

[Robert M]

tank closing

Also, when it comes time to close and seal the tank with the inspection cover, use socket head screws to hold the cover on. You may never, ever have to remove them but the phillips head screws will be a pure booger to get out considering you have them in platenuts WITH proseal.

I'm using socket head screws where ever practical on the airplane.

 

[Mel]

Robert is correct. Don't be stingy with the proseal! I built my tanks over 17 years ago and have never had a leak.

 

[Kyle Boatright]

I'm just about ready to start sealing my first tank on my -9A.


3)While I'm at it, when I'll back rivet the stiffners in the tank, I won't cover the rivets with pro-seal. I'll put a nice layer on the stiffner, install and back rivet, make a nice filet and cover the rivet's head. For the ribs, do I need to add pro-seal to the rivet's before driving it?

Thanks!

There are only a few places a tank can leak. At a rivet, at a baffle seam, or at one of the other penetrations (quick-drain, etc) of the tank's external skin. Make sure you have plenty of proseal in all of those places and you won't get a leak.

I would dab proseal in every rivet hole before inserting the rivet. Also, I would put a blob of proseal over the inside surface of the hole before clecoing the stiffeners (or internal ribs) to the skin. Those are the things which will help eliminate tank leaks. Proseal smeared along the faying surface of an internal rib or stiffener is just extra weight unless it is *at* the hole.

 

[llavalle]

Alright, thx guys. The rivets are already soaking to be clean. I'll probably start riveting the stiffners this afternoon.

My pro-seal is expiring in october, I can use it all on the first tank. Anyway : who's going to see in there!

 

[Mel]

My pro-seal is expiring in october, I can use it all on the first tank. Anyway : who's going to see in there!

Keep the proseal in the refrigerator and it will last indefinitely.

 

[MNAv8or]

Keep the proseal in the refrigerator and it will last indefinitely.

Not entirely true. We keep it in the freezer (if already mixed) to extend the life and the fridge (if unmixed) but have found that when taken out and warmed up to room temp to mix, sometimes (rarely but it does happen) the sealant won't kick off and cure when left to set. We have tried heat lamps and anything else you can think of to try and get it cure. It is not fun pulling a windshield back out of a Cessna 340 because the sealant won't cure. As I said it is rare that this happens but it does happen. I have also had pro seal right from the factory fresh not kick off either.

When sealing your tanks, don't throw away the excess sealant. Instead put some in a cup and leave it sit right next to your work area (really comes in handy when you close up the tanks). This way you can tell when your sealant is cured without having to touch the actual product. If you look closely at Citations you can see that they do not follow this method at the factory as I find fingerprints in sealant all the time where it was tested.

 

[flion]

Just a couple of things: cleaning rivets is one thing (BIG PROSEAL SECRET #1, clean everything meticulously and wear powder-less gloves to keep it that way) but swirling rivets in proseal is just an invitation to get proseal everywhere. AD3 rivets are hard enough to handle with glove-less fingers; add gloves and proseal and it can be a nightmare. However, if you've put enough proseal on the mating surface, then it will ooze - not only out the edges but also into the rivet holes, even if the rivets are already placed (for backriveting the stiffeners). If you're not seeing ooze around all the edges, you're using too little but the chances are you will be using too much and will be removing the excess from around the stiffeners/ribs and off the surface of the skins where it has oozed during riveting. For the ribs, you just need to make sure that when you remove a cleco before placing a rivet that you get the glob of proseal on it back into the hole before placing the rivet. This is much neater than gooping your rivets.

You do want to put a film of proseal around shop heads, and that includes the external ones on the end ribs. Otherwise it's possible that a gap in the inner fillet could allow fuel to seep between end rib and tank skin and escape via a rivet. It's pretty cheap insurance to do the outsides, including the big rivet you just put in. By film, I mean 'paint' a little on using a gloved finger; you don't need the heavy application I saw in your other thread.

Finally, you mentioned the attach angle. Proseal will stick to the primer but I would suggest either masking off the mating surface when you prime or sanding and cleaning the primer off before you rivet this part on. Then you can proseal it in place, more effectively sealing the rivets here and the proseal will protect the unprimed surface as effectively as primer.

My tanks were only built 13 years ago but they sat dry for 12 years before having fuel put to them. In that time, I leak tested them three times (fuel sender work) and have had no leaks in the year since I first filled them with fuel. From what I saw in your other tank sealing thread, I don't anticipate you will have any problems either.