This log entry represents work over several days during this past weekend. I started by continuing with more countersinking of the first side of the left spar. After countersinking, I protected all of the exposed aluminum with a Alodine Touch-N-Prep pen, though the shape of the applicator tip was a little challenging to fit into all of the countersunk holes.
Next was to try to flatten the flap hinge brackets, which were slightly concave from the factory hole-punching process. The instructions recommends a technique of putting the piece in a vice, applying pressure, and then hitting with a hammer. However, I wasn't getting much progress with that method and it was starting to leave marks on the surface, so I switched to using a hydraulic press and that worked out much better.
Then I spent some time preparing the ribs by ensuring the flanges were all 90 degree to their webbing, fluting the flanges to make the ribs sit flat, and removing the part stickers, adhesive residue, and stamped ink marks.
What's next? There are a few more ribs to finish prepping and fluting, and then I can start assembling all of them onto the rib with clecos. I also have more countersinking to do on the other side of the rib.