Page 8-2 Deburred all of the match drilled holes. Machine countersunk the holes that will match the dimpled parts of the firewall. Machine countersunk the #30 rivet attach holes on the F801L backing plate. Machine countersunk the #40 nutplate attach holes on the F801F-1 middle angle and F801H-R1 center angle Machine countersunk the nutplate attach holes on the aft side of the F801D1 lower angle Riveted the nutplates to the F-801H-R -1 Center Angle as well as the nutplates on the top flange of the F-801F-1 middle angle