The screw holes in the plenum were enlarged to #19 size. The small doublers that Scott had made were clecoed to the plenum flanges. The rivet holes were drilled in the flanges. The doublers were removed, the screw holes were enlarged to #12, and the rivet holes were countersunk with the deburring tool. K1000-8 nutplates and the doublers were riveted to the flanges with AN426-3-4.5 rivets. Four doublers need to be modified to fit the flange because of interference.
The plenum with doublers and nutplates riveted in place
