Longerons Matched Drilled To Panel Base

The original task for the day was match drilling the top of the longerons to the F-1202B panel base. Before getting involved with the drilling, the plans were closely scrutinized because a small issue caught my eye regarding the F-1201B firewall shelf. The page of the plans calling for the match drilling of the panel base to the longerons also has a detail showing the mounting of the F1295-L&R stiffeners. Close inspection of the detail revealed a small issue … four rivets would need to be drilled out to install the F-1295-L&R stiffeners. Thinking I may have made yet another screw-up, paged back through the plans to the page that calls for the riveting of the F-1201B firewall shelf to have a look. The plans made no mention of leaving those four rivet holes open. There was mention of leaving holes in the firewall shelf open … just not the holes in question.

My fingers are pointing to the two rivets which need to be drilled out … this will allow the F-1295-R stiffener to be riveted to the underside of the F-1201B firewall shelf.

One can see all six rivet holes in the F-1295-R stiffener that need to attach to the underside of the F-1201B firewall shelf.

I believe this is a case where the F-1295-L&R stiffeners were added later to the RV-12 kit and the wording in the instructions had not caught up yet. Sure glad I discovered this prior to having the side skins installed, otherwise it would have been much tougher to remove the two offending rivets on each side of the F-1201B firewall shelf. As it was, the two rivets closest to the upper firewall posed a bit of a challenge because the rivets were so close to the upper firewall that the body of the drill prevented a straight shot at the rivets. Ended up using a 12" drill bit to drill out the two rivets closest to the upper firewall.

Flexing a 12" drill bit to get a reasonably straight shot at the head of the rivet so it could be drilled out.

Right side of the F-1201B firewall shelf after the two rivets were removed. The outermost row of rivet holes needs to be open like this on each end of the F-1201B firewall shelf to allow instillation of the F-1295-L&R stiffeners.

After correcting the above issue, work began on match drilling the F-1202B panel base to the top of the longerons. Following the instructions, the outer edge of the longerons were aligned with the edge of the F-1202B panel base and clamped in position for match drilling.

Match drilling #30 the F-1202B panel base to the right longeron.

Once the right longeron was match drilled to the panel base, the same procedure was used to match drill the left longeron. After both longerons were match drilled to the F-1202B panel base, the Clecos were removed and the parts were deburred.

Finished match drilling of the F-1202B panel base to the left and right longerons.