Began work on the rear spars. Locate all parts, de-burr edges and remove vinyl as needed. Straighten both W-907B reinforcement forks. Match drill The fork and W-907C doubler plate. Carefully select and countersink doubler plate holes as needed for flush head rivets as per the rivet callout. (Both left and right spars) Dimple upper spar flange hole to accept skin dimples. (Will not be accessable after reinforcement fork is installed.) Disassemble and deburr all holes.