Fuel Tank Leading Edge Question

[Flandy10]

I am wondering if anybody else with a SB wing kit has had problems installing the ribs into the fuel tank skins?

I spent 2+ hours (left tank only) trying to get the matched holes to line up. Yes, I fluted and straightened each one. Tried working both in and out of cradles. It took two people and what seemed to me as excessive force, but they are installed. The problem appears to be that the "pressed" skin radius is different than the ribs' radius. I've checked a few QB tanks around here and they look close to mine.

Searched Matronics and there are a few posts back in 04' and 05', but nothing useful. My kit left the factory in June 05', meaning, second hand rules apply here.

Any similar experiences or thoughts?

 

[paul330]

Welcome to the "can't get the leading edge ribs to fit" club!

- make sure the flanges are square. If anything have them over-bent by a couple of degrees. This particularly applies to the small tabs at the front without the rivet holes.

- ensure you have sufficiently fluted especially around the tight edge at the top. It needs to be VERY heavy - that's where I went wrong initially. Use a straight edge to ensure the rib holes are correctly lined up.

- blend out the corners on the flange slots on the tight radius. This is well documented in the forums but, IIRC, only mentioned in the HS stab instructions in the manual. You can use the corner of the scotchbrite wheel but be careful - the material is removed VERY quickly You should end up will a scalloped shape.

- it gets easier after the skins/ribs are match-drilled and dimpled.

Good luck!

 

[Bruce9A]

similar problem/possible solution

I had what sounds like a similar problem on my 9A. I cleaned up the sharp edges on the ribs, but that only helped a little. The problem seemed to be that the skins weren't bent to the same shape as the ribs (the bend in the skin was a little too sharp). What worked for me was to unbend the skins a bit. I used a long board positioned lengthwise to hold the skin down on a flat surface and another to lift up on the inside surface of the skin. I tried to apply the spreading force as close as possible to the leading edge. All it took was opening up the angle by about 10 or 15 degrees. The tanks and leading edges went together much more easily after that. Of course, the problem you're experiencing might be due to something else, but this is what worked for me.

-Bruce

 

[rleffler]

I found that if you are attempting to cleco one rib at a time, it's problematic. My solution was to cleco one side of the tank skin to all the ribs on one side first. Then flip the tank and with the assistance of another person, cleco only the first hole (leading edge) on all ribs. Then move on to the second, then third, etc. I found this kept the pressure more symetric and easy to get the holes to align.