Bolted control column mounts to their respective bulkhead assemblies and squared them up relative to left and right seat brackets. Clamped them in place and drilled the remaining bolt holes, then removed the mounts and deburred them. Following the procedure in the manual, drilled #12 the other bolt hiles. Removed the bolts and upper bulkhead and the covers. Drilled the #30 holes formerly hidden by the covers. Removed the seat supports and deburred them. Clecoed the remaining bulkhead parts to the forward bottom skin and drilled the #30 holes connecting the bulkhead parts to the floor ribs.