The drilling of the rear spar bolt holes is the final step in wing attachment process. Once these holes are drilled, the sweep and incidence is locked in. An error in the drilling of this hole would result in a whole lot of schedule slippage due to rework on both the fuselage and wing structures to replace the misdrilled components. The hole must be located to provide a minimum of 5/8″ edge distance from the centre of the hole on all rear spar attachment components. It also must be drilled perpendicular to the rear spar stubs, which is tricky as all surrounding components and edges are at a variety of angles.

I used a 5/8″ spacer to draw lines on the rear spar tab to establish my boundaries. This provided me with a 1/8″ box to locate my hole in. I drilled a shallow indent inthe centre of this box and then used a drill guide to maintain a perpendicular drill angle for the first pilot hole (1/8″). I repeated this procedure, using a drill guide as I opened the hole up to final size of 5/16″ in steps of 3/16″, 1/4″ then 5/16″. This worked well for both left and right wings.

I then moved on to the fitting of the gap seal strips where the wing intercepts the fuselage and the drilling of the holes in the bottom wing skin where they overlap the fuselage lower skin. These holes will be opened up to final size, dimpled, countersunk and nut plates installed once the wings are removed from the fuselage.

I am happy I was able to get the wings on the fuselage and work thru this stage of the build without having to move the aircraft outside. The weather has been very active for the last three weeks which would of likely pushed me into working too quickly and perhaps screwing something up in the process.