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Fuel tank question

Eric B

Member
Just got my wing kit in and was perusing the new plans, when I stumbled across what I have been hearing about: the wing plans are not quite as clear as the emp plans are.

Case in point. Page 18-4, step 6 says to machine ctrsnk the row of holes holding the tank skin to the rear baffle. But, it says it in such a way that it looks like the skin should be ctrsunk. Can't be right by my standards, but my stards aren't always right... So, can anyone out there affirm that the baffle should be ctrsunk, while the skin should be dimpled?

Also, please be aware that I'm in the middle of inventory so I can't say that I've paid that close attention to the thickness of the parts in question nor the plans. If dufus I look like, then dufus i probably am... :cool:

Thanks guys,
Eric
 
As I recall (and I could be wrong), you countersink the skin. The baffle to skin point is THE leading cause of tank leaks. If you were to dimple the skin and counterink the hole and the hole doesn't accept the dimple perfectly, you now have a gap between the baffle and the skin. Bad thing.

Also, when you put the install the baffle onto the tank, what you're going to do is run a bead of tank sealant along the holes (or just below them) and your baffle is going to act like a squeegee as you push it into place.

If those holes were dimpled, you'd likely lose the effect of the squeegee and wouldn't end up with a nifty roll or fuel tank sealant.

There really isn't a structural issue here. For one thing, the tank skin is pretty thick but beyond that -- as Van's explained to me -- you've got each rib sealed to the skin, and riveted to the skin. A countersunk hole on the skin ain't gonna hurt you.

and, trust me, baffle leaks really suck.
 
Fuel Tank Coutersink

The instructions are correct, the rear baffle / skin is countersunk (vs Dimple). The wing walk area right beside the cockpit is also machine countersunk.

Jim C
 
Cleco every other hole along the skin / baffle plate joint.
Use the microstop c'sink to machine through the skin and partway into the baffle plate just enough to get the rivet to sit flush in the hole.

Steve
 
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