After shooting and bucking the rivets along the top of the spar (the left side of this picture), I weighted down the flaps on the kitchen countertop just like the ailerons, and squeezed the rivets along the bottom of the spar that holds on the flap hinge. This picture looks funny because the top skin is reflecting (and distorting) the spar lightening holes.
The plans call for LP4-3 rivets here, but I’m running short, so I set AN470AD4-4 rivets here instead. I shot and bucked these solo using a double offset rivet set since you can’t get a squeezer in here.
The two flap brackets are riveted together using 5 AN470AD4-7 rivets. These rivets help transfer the force from the flap pushrod into the spar.
Finally, a few MK319-BS rivets are used near the trailing edge of the flaps (where there is no access to buck these). I had to use one additional MK319-BS rivet on the bottom of each flap (shown here near the top of this picture) when the flap pushrod nutplate interferes with bucking this rivet.
