F21-01 Fuselage Tail Cone Box.
I drew blue lines on the flanges of the lower cross ties to aid in the proper placement of the lower aft fuselage skin. I placed the lower aft fuselage skin on the assembly and aligned the pilot holes with the blue lines. I drilled the #40 pilot holes into the lower cross ties and logerons using the lower aft fuselage skin pilot holes. I removed the #1 lower cross tie, the Zee channel and slpice plate to gain access to drill the holes at the lower splice plate locations. I first drill the skin holes at the logeron location using the pilot hole in the longeron as a guide. I then attached the Zee Channel and the #1 lower cross tie. I temporarily clecoed the splice place to the top of the skin at the longeron locations. I then used the splice plate as a guide to drill the #40 pilot holes through the skin and #1 lower cross tie. I then clamped the spacer to the splice plate to use it as a guide. I drilled #40 pilot holes in the spacer. I then clecoed the splice plate and space back into the proper location. I up drilled the two holes for the AN525-10R bolts to 3/16th. I up drilled the other three holes on the splice plate to #30. I also up drilled all the holes on the #1 lower cross tie to #30.

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