Match-drilled F-881-1 mid cabin covers through longerons. Using F-883-1 fuel valve bracket to mark layout, drilled 3/8" hole in left side cover for fuel valve handle. Drilled and countersunk #40 holes for nut plate rivets in longerons using angle drill adapter. Broke guide tip off countersink bit when it bound up in one rivet hole. Riveted four nut plates to longerons, using vice grips as squeezers. Turned out to be a difficult job; drilled out a few rivets, others less than optimal but ok for nut plates.
