Verified fuselage and workbench were level. Verified fuselage sides were square with bottom. Used plumb bob to verify centerline of 6B3-6 was aligned with fuselage bottom skin centerline. Drilled centerline holes into HT panels. Cut 'L' angle pieces to along sides of opening in 6B3-6. Trimmed to fit inside of upper longerons at aft edge. Clamped in place with vertical scrap pieces to ensure alignment with opening. Drilled and clecoed right side then left.
