Fabricated and installed L-angle reinforcements that surround the flap actuator hole back by the rear frame channel (the place where the aft wing spar attaches). The job was straightforward, but made longer due to the need to unrivet and trim one of the rear fuselage stiffeners (on each side) I had made too long originally.
From the outside - the one L-Angle will need to be trimmed back from the hole.
From the inside - the 2 L-angles form a triangle with the lower rear longeron.