The VS-803 rear spar was match drilled to the VS-808 spar doubler. The lower holes need to have AN-426 flush rivets per the plans in order to attach the vertical stablizer to the fuselage. Consequently, the VS-802 spar channel was dimpled and the VS-808 spar doubler was machine countersunk. Everything was then disassembled and deburred. The flanges on the spar channel were then dimpled and the edges polished on the Scotchbrite wheel.
Dimpled and Countersunk Rear Spar
Rear spar drilled, deburred, dimpled and countersunk
