M

Mark Jackson

Active Member
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As I near the end (hopefully) of my second set of tanks, I think I'm finally getting wrapped around how they should be built. It's a little different from the way Van's has one do everything.

It would seem to me the logical steps would be to assemble/drill/deburr/fit parts, etc. Then disassemble and clean with solvent. Then proceed with mixing sealant, back rivet the stiffeners. Next day/session, fuel caps and drains. Next day/session - add sealant to the bottom of the various ribs, cleco them in place, let dry. (I believe this is called fay sealing? I have ordered the curved dental 100 CC syringes from ebay, they're excellent for this.) Wait a day. Repeat for the top of the ribs. Wait a day to let dry.

Shoot the rib rivets dry (without dipping each rivet in sealant.) Once all the rib rivets are shot, "paint" all the inboard seams and filet the back of the inboard ribs with pro-seal. (This is what Mooney did in my Mooney tanks).

Finally, install the 401 plates, vents & fittings, fuel level senders, etc. Seal everything.

Lastly put on the rear baffles.

Is there a reason that Vans calls for each rivet to be riveted into place with proseal in the hole? I'm curious to hear of everyone's experiences/thoughts.

My first tanks followed the Van's instructions and worked except I didn't use enough sealant on the baffle and was never able to fix it.
 
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I think the reason for dipping the rivets is 'belt & suspenders'. If the sealant on the flange around the rivet hole doesn't seal, and/or the sealant you later apply over the shop head doesn't seal, then hopefully, the sealant in the dimple will hold.

On the other hand, if the sealant in the dimple seals, all the rest is just along for the ride. (All that sealant on the interior ribs that isn't adjacent to the dimples is along for the ride, regardless.)

If you're going to rivet 'dry', and 'paint' all the seams later, why not just build the entire structure dry before painting the seams/shop heads? Pretty sure it's been done on a few RV's, and definitely on some other designs.

Charlie
 
I followed Van's instructions and it all worked well. Obviously it has been done successfully several other ways. But it was simple enough to do it per the manufacturers instructions without any problems. I prefer to have poseal applied and dried in one step rather than apply to the flange, cleco, let dry, and come back and do fillets that may have a less than perfect bond to the dried proseal.
Everybody seems to fear the tanks and proseal. I found it not to be that messy or that difficult.
 
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