Assemble
3/24/23 - 2.7h
3/25/23 - 1.6h
Flap assembly starts by building up the nose rib parts. The inboard rod end ribs each get doublers, and the outboard rod end ribs each get doublers and nut plates. Van's specifies the direction of the rivets in the drawings. In this case, the manufactured head goes against the ribs, and the shop head is set on the doubler. The nutplate rivets are set in the opposite direction to attach the nutplate inside the rib with flush rivets on the doubler. The pneumatic squeezer had good access to set all the rivets.

The hinge assemblies start similarly to the rod end ribs. The hinge brackets are riveted to their corresponding rib, with the manufactured head against the ribs, and the shop head set on the hinge brackets. The pneumatic squeezer had good access to set all of these rivets as well.

The final task in this step is to rivet left and right hinge/rib pairs to each other. This is a little different than previous riveting tasks because the rivets are set double-flush. The process starts by clecoing the hinge sub-assemblies together, and inserting the flap hinge bushing to keep the hinge brackets aligned properly. I was concerned that the clecos didn't hold the hinge pairs tight enough, which could lead to setting bad rivets, so I supplemented the clecos with c-clamps. The other thing to keep in mind is setting the pneumatic squeezer too tightly will prevent it from generating the maximum compression on the rivets. The shop head of the double-flush rivets completely filled the countersink, and ended up just very slightly proud. I sanded the flanges smooth, and was very happy with the results.
[Pneumatic Squeezer, 1/8 Cupped Squeezer Set, Flat Squeezer Set]