F21-01 Fuselage Tail Cone Box.
I located and drilled #40 pilot holes for lower cross ties #2 thru #5. I used two squares clamped together to make sure the sides were square at each location. I also test fit the lower skin several times as I went along. I also located the aft bulkhead (F23-02) and Forward Lower Mount Angle (F23-03). I drew a blue line on the flanges of the bulkhead to locate the holes in the side skins. I clamped them in place and drilled #40 pilot holes. I did not drill the holes for the bolts that will attach the Mount Angle to the Longerons and lower skin. I will wait to do that when I drill the holes for the lower skin,

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