F-976 Rivet Spacing

[MTBehnke]

I'm having a tough time getting the rivet holes around the F-705 bulkhead to line up with the F-976 bottom skin. Everything looks put together right, the rib flanges look bent correctly, rib and bulkhead holes drilled correctly, all the parts fit nice, etc. As you can see in the picture below, the bulkhead and baggage rib holes are all off by about 1/16".

In talking with Gus at Van's he thought that the bottom skin rivet spacing I was measuring between the aftmost seat rib rivet holes and the F-705 bulkhead rivet holes was less than what he could guage by his drawing, but doubts the skin is drilled wrong.

Can someone do me a favor and measure their rivet hole spacing in their F-976 bottom skin?

 

[keen9a]

Mine looked like this at first too. The aft end of the baggage ribs were just sagging a bit. Hold down the F-905 bulkhead, and pull up on the aft end of the baggage ribs, and the holes should align. Once you get a couple of clecoes in place, the rest are no problem.

 

[MTBehnke]

Ben - that's what I was originally thinking as well, but when I angled the F-705 bulkhead and baggage ribs enough to get a cleco in, it was very clear that wasn't right. In fact, the gentle curvature of the bottom of the fuselage was reversed. Also, the F-904 and F-905 bulkheads should be parallel, based on measuring the side skins. When I angled the baggage ribs the bulkheads were quite a bit off of parallel.

All I can think is that either:

a) the aft flanges of the seat ribs are all bent wrong. This is unlikely as they are all 5/8" wide (typical width) and it's unlikely that all of the different types of seat ribs were all bent incorrectly, but all exactly the same.

b) the bottom skin rivet holes are misaligned.

Still puzzled, but thanks.

 

[Brockster]

I had same issue and here is what worked for me. When inserting clecos, start with 705 bulkhead and cleco entire length of bulkhead before any where else. Once 705 is clecoed start working your way forward and aft. If the holes immediately for and aft of the bulkhead don't line up, go further fore and aft till you can get a cleco in fairly easily. Ribs are more flexible further away from bulkheads. With 705 clecoed and putting clecos in the ribs where you can things will begin to line up. Cleco 904 bulkhead last. Hope this helps.

 

[MTBehnke]

Paul - I tried your approach and was able to get all the cleco's in. What seems strange to me is how the skin changes its bend at the F-905 bulkhead. With a straightedge on it you can see about a 3/16" gap. So maybe this is right afterall?

 

[Brockster]

Mike, I am at work and cannot verify at this time but the gap might be slightly big. I will look at mine when I get home and let you know. Mine is upside down with firewall installed ready to disassemble for final deburring,etc

Yep mine is the same as yours and everything fits well, your good to go.

 

[MTBehnke]

Thanks Paul and Ben - I will build on!