Section 21 Deburred two F-1203E-R Bulkhead Doublers. Pg. 21-12 Step 1: Separated two F-1203J Bulkhead Doublers. Deburred F1203J-L & R Bulhead Doublers. Deburred F-1226-L & R Seat Ramp Floors. Primed the contact surfaces of previously deburred brackets and doublers. Pg. 21-10 Step 2: Countersunk the four holes surrouning the bearing holes on the outbd side of the Control Column Mount Brackets. Countersunk the nutplate rivet holes on each bracket. Step 3: Riveted the bearings and spacers between the Control Column Mount Brackets forming double flush rivets around the bearings and using LP4-4 rivets for remaining holes.
