The ailerons and flaps must be mounted to the rear spar so that they are properly aligned with the rest of the wing. They must form a nice smooth continuation of the wing surface. Van suggests to make some two piece wing wing profile templates from plywood, and to use these to help get the ailerons and flaps in the right place. Here you see the right aileron in position.

Once you get the aileron in the right location, you are supposed to clamp the hinge brackets to the aileron and drill the holes the hold them in place. I clamped things in place, but then couldn't get a good shot at them to drill the holes. So, I made a million measurements that basically confirmed that they should be located exactly as per the plans, then drilled everything on the bench. I held my breath when I put it all back in the templates, but everything worked out fine.

After mounting the right aileron, I went on the road to Brazil for two weeks to fly the EMBRAER EMB-145 Regional Jet. It was a fascinating trip, beautiful country, and great people.

After I got back, I made the various spacers that fix the aileron in position laterally, made the pushrod that goes from the aileron bellcrank to the aileron, and pinned the aileron in the neutral position.