At this stage, I have both flaps cut to length with all trimming done. The second picture shows one flap and the four ribs that will be mounted to it. The ribs are supplied in the kit, the drive horn plate was also supplied. The drive horn assembly is made from the plate and a rib. Those are the first pieces are riveted together. Note that eight ribs are supplied, four with flanges bent one way and four with flange bent the other way. You then use three of one type of rib with one opposite rib which has the drive horn attached. This way you have no exposed flange on either flap.
In the bottom two pictures I have marked and drilled pilot holes in the flap. I then drew a blue line down the center of each ribs flange and used that to line up the rib with the pilot holes in the flap. Then I drilled a 3/32” hole in the rib through the pilot hole and put in a cleco. After all the holes were drilled and the rib attached, I updrilled the holes to 1/8”.
