<October 21, 2007>

F-776 Bottom Skin & F-623 Corner Ribs

Since I still don't have the replacement F-712B Bulkhead, I continued with the center section today. I was able to get the bottom skin mounted and drilled, the F-623 Corner Ribs drilled, and take care of some dimpling I had forgotten to do the other day.



First thing I did was to flip the center section upside-down on the floor and cleco and drill the F-776 Center Bottom Skin. The fit was OK, for some reason it fit fine everywhere except for the holes attaching it to the F-705 Bulkhead. The fit there was snug, so I put a cleco into every hole of the F-705 holes, and removed each individually for drilling.

Next up was the F-623 Corner Ribs. I placed them in the right location and marked them for trimming. The instructions are very vague here, but you want to align this so that the side skin aligns with the edge of the bottom skin. Here is a good explanation with a diagram.

After some trimming, fluting and flanging, here is what I ended up with. I am not sure if the flutes are in the right places, but I'll worry about that later.

You have to trim the aft end as well so that it doesn't hit the flanges of F-706 Bulkhead, and here is what I came up with. When I was satisfied with the fit of the first rib, I used it to mark the second for trimming.

Clamped and ready for drilling.

All drilled. Looks good so far.

This is a pretty cool part. I am starting to run out of room in the shop with these big assemblies around.

When I dimpled the side skins a few days ago, I had forgotten to drill and dimple the hole for the screw that is used to clamp the rudder cable housing. Fortunately for me, with the F-711 and F-712 Bulkheads already removed, this was a simple task. To drill the holes (to #19), I first clamp a piece of scrap wood in place to provide some support while drilling.

It was then an easy task to slide the squeezer with the longeron yoke up the fuselage over the j-stiffener from the open aft end of the fuse.

Perfect, scratch one more thing off the list.