Finished the transponder tray cross brace by drilling the holes for #8 screws at each end of the brace through the angles I had riveted to the forward fuselage ribs earlier. I marked the location on the cross brace for the 2 MS24693S26 screws and match drilled through the transponder tray. Then I machine countersunk the tray for the screws. After deburring all the holes I secured the brace to the ribs with #8 screws and locknuts. I secured the transponder tray to the brace with #6 flat head screws and MS21042-06 nuts. I found 3 locations on the sub-panel to cut race track cutouts for the avionics wiring hardness d-sub connectors to pass through. I used a step drill to drill 6 holes 3/4" in diameter at each end of the cutout. Using a cutoff wheel I cut between the holes for my harness slot. Deburred the edges. In order to support the harnesses with ADEL clamps I cut 3 pieces of 0.063 aluminum angle and marked the location for AN470AD rivets. I drilled those holes and then mark drilled to the sub-panel so the angle flat was right at the edge of the harness slot. I deburred all the holes and primed the 3 angles. Last I riveted the angles to the sub-panel with AN470AD4-4.5 rivets. I used MS22529/2-2R grommet edging in the slots to protect the wiring harnesses.
