Fuselage - Forward Section

2006-04-16 - Fit the main gear before riveting the side skins. (4.0 Hrs).

No riveting today, either. After deburring the bottom skin yesterday, I thought maybe I should try to fit the main gear weldments in place before the floor is riveted on. When I first put the weldment in place, it looked like it would be impossible to fit it in with the bottom skin riveted on. Then, I figured out that the F-782B cover support ribs are removable, which makes it easier to fit the weldments in place. Anyway, I spent the day fitting the weldments in place and drilling them to the side skins.

Left main gear weldment in place with F-782B removed.
With the weldment in place, it is clearly not seating against F-704 due to the F-704 flange contacting the weldment. The cutout on the flange needs a little more trimming (actually some aggressive filing with a rounded file).
After filing the flange down a bit, the weldment pulled-up against F-704 real nice like.
One of the reasons to fit the gear weldment now is to drill the holes for the leg that attaches to F-7101 on the side of the fuse. It may be hard to see from this angle, but one hole is actually blocked by the F-902 bulkhead.
So, what I did was to drill the reachable hole from the inside, then measure where the other hole should be, and drill it from the outside--worked great.
One other reason to do this now, is that these holes take an AN509-10R12 screw. That happens to be a countersunk screw. If we don't do this before the skins are riveted on, then we won't be able to dimple the side skins, and countersink the lower longeron. Thanks, Van, for such good instructions!

Ok, in Van's defense, as you can see, he says to machine countersink through F-770, F-772, into the F-717 lower longeron. I guess that would work, but I prefer to dimple F-770.

If you do this now, you can remove F-717 and countersink it on the bench. Note, I started with the bit on the left, but it really mucked-up the hole. I think it is a different angle. I finished with a 5/32" bit for a #8 hole using my electric screwdriver. Even though the pilot was too small, using the electric screwdriver, the countersink came out perfect (well, almost). I need to toss that other bit.
Looks good on the outside.
Looks good on the inside.
One other thing I wanted to do today, was to make sure that I riveted the other F-719/F-719B angle clip to the firewall. The angle clip was previously riveted to F-719, so all I needed to do was rivet the angle clip to the firewall.
You need to remove enough clecos so you can pull the skin back and get the squeezer in there. Not a big deal, but I am starting to worry that if I remove the clecos one more time, the holes are going to be enlarged too much to rivet.
The right weldment fit without any filing--woo hoo! Done for the day.