Referback to the the wing flap hinge installation section, and refresh your memory about the Flap Alignment Templates, located in the download section. The alignment of the flap ribs and flap hinges to the existing wing hinges is the most critical step in the fabrication of the flaps. Cut out the templates as shown. I used foam I found at Home Depot used for building insulation, it is 1/4" thick and covered on both sides with a plastic film. It is also referred to as fan-fold-foam. Anything will do as long as it is somewhat rigid.

Tape the patterns to foam or other template material

Cutout the wing section

Mount to the Wing, the hinge bolt is the key reference

Mount all three templates to the wing and sight down them to insure they are all lined up porperly. Do the trailing edge points line up? If not determine why and correct the alignment.

Rib located with template

The flap ribs are then located using the template to hold them in the proper position. Some further parts of the template may need to be trimmed away to clear parts of the wing flap hinge.

 

Rib located with template

Finally the flap hinge is also located using the template, clamped into place with small C clamps.

Flap hinge located using template

Finally the Rib is removed, the holes are drilled and AN3 hardware is used to attach the rib to the flap hinge.

Flap rib clamped to flap hinge.

The final step is to reposition the flap rib and flap rib using the template and confirm all is in perfect alignment with the hinge fully retracted. A single 3/32" hole is now drilled through both the flap hinge ad the mating wing flap hinge to lock the hinge in the upmost locked position against the stop. With a bolt through this hole, the flap rib should be positioned perfectly and the template can be removed.