Assembly Of Upper Forward Fuselage Begins

After taking a week away from the project due to family issues, assembly of the RV-12’s upper forward fuselage components begins. The F-1201H upper forward fuselage doubler was test fit onto the F-1201A upper firewall to verify good rivet hole alignment … in particular on the ends. Earlier builders mentioned the flanges on the firewall may be an issue but mine allowed all the rivet holes to align nicely.   However, builders should take notice of both ends of the F-1201H upper forward fuselage doubler ... the ends need to be curved inward so there will not be pressure pushing outward on the side skins when they are placed over the doubler.

Using Clecos to attach the F-1201H doubler onto the F-1201A upper firewall for a test fitting.

The end of the F-1201H upper fuselage doubler needs to be curved inward so it sits flat against the F-1201A upper firewall. It did not take much tweaking to correct this on each side.

Weeks ago I verified that the F-1201P firewall spacers sit flush with the forward edge of the F-1270 side skins when all the rivet holes are properly aligned. The reason I did this is because the side skins are dimpled thus the spacers and cowl hinges will also need to be dimpled as well for the flush rivets being used on the RV-12 project. However, the F-12116 hinges require match drilling first. The plans have the builder assemble all the pieces then match drill through the side skins … but because the side skins are already dimpled (and not installed), the not yet dimpled rivet holes in the F-1201P firewall spacers were used to match drill the F-12116 cowl hinges. Because tighter match drilling can be accomplished when the pieces are not dimpled, I felt that was the best way to get the hinges match drilled was to align the hinges to the F-1201P spacers since they fitted flush with the side skins. The base of the cutouts for the hinges were aligned flush with the forward edge of the F-1201P spacers, clamped in place, then match drilled to the F-1201P firewall spacers.

The F-12116 cowl hinges clamped onto the F-1201P firewall spacers ready to be match drilled.

After the F-12116 cowl hinges were match drilled, the parts were deburred and dimpled then placed in position to verify fit.

Testing the fit of the F-12116 cowl hinge and F-1201P firewall spacer on the F-1201A upper firewall assembly after dimpling the parts for flush rivets.

At this point it is back to following the plans which call for riveting the F-1201P firewall spacers onto the F-1201A upper firewall by way of ONLY the top rivet in the nutplate common to the parts. The bottom rivet hole in the nutplate and the lower four holes are to be left open at this time.

Riveting a nutplate onto the F-1201P firewall spacer/F-1201A upper firewall assembly … only the upper rivet in the nutplate is riveted at this time.

Next the plans instruct the builder rivet nutplates and the F-1201H upper forward fuselage doubler onto the  F-1201A upper firewall.

Riveting together the nutplates and the F-1201H upper forward fuselage doubler onto the F-1201A upper firewall.

Fruits of the day’s labor … the F-1201H upper forward fuselage doubler is now permanently attached to the F-1201A upper firewall along with 25 nutplates.