Step 20:Removed the blue vinyl from the F-1270A and F-1270D Side Skin Doublers and clecoed them to the fuselage.
Step 21: Match-Drilled #30, using good drilling technique, all the holes in the Side Skin Doublers into the Fuselage Side Skin, Seat Floor Supports, Baggage Corner Skins and Fuselage Corner Skins where holes did not already exist.
Step 22: Machine countersunk all rivet locations in the Side Skin Doublers where CS4-4 rivets will be installed, using a 120 degree cutter with a #30 pilot.
