There are two gear channel doublers for each side of the plane - one goes on the front edge of the gear channel, the other on the rear.
They are shipped as plain straps of aluminum. Tehy are held in place with 3 AN3 bolts and 11 A5 rivets. Beffy. One starts by laying-out 12 #40 future rivet holes and place one 3/16" hole 10mm from one end. Since they are all prepped the same, I clamped all 4 together and drilled all 4 at once. Saved a little bit of time but a lot of tedium.
With the gear mount weldments in place, I used a right-angle drille to drill thru the 3/16" / AN3 holes in the weldment into the gear channels. A cleco thru the outter-most 3/16" hole holds the doubler in place so the builder can then drill thru for the other 12 holes. The far end is then updrilled to 3/16" while the other holes are #20. Once all cleco'd in place, the builder back-drills thru the mount weldment to position the second outboard 3/16" hole. Repeast 3 more times.
Removed the cabin frame so that I could get the garage door operable again (this is a tall plane when on a bench). Installed the outboard seat supports for L & R seats; they'll be drilled tomorrow.
Trial assembly & drilling of the fwd fuselage is complete. Not I well un-mate the fuselage halves, double check that I didn't miss any holes, debur, and rivet together. Then re-mate the fuse.
Doublers all drilled at once (4th one in the plane)