Remove protective vinyl, durred, and prepared blukhead flange, stub spar receptacle support, and stub spar receptacles, as directed. Countersunk 38 #40 nutplate attach rivet holes and 6 #30 holes in the bulkhead areas indicated. Enlarged three 1/8" holes in the builkhead to 7/16". Enlarged one 1/8" hole in the builkhead to 3/4". Modified one 7/8" bulkhead hole to make it completely circular, as directed.