Bulkhead work continues. This time, it's time for the center section. This plan comes already with the wing kit. The reason for this is that this is the section where the wings will connect.
It's a massive construction that will carry most of the load of the airframe.
The main sections are pre-assembled by Vans because they are matchdrillled with the spars of the wings in the Vans factory.
I guess they don't want you to screw up here as it' s one of the most vital sections of the whole airplane. The bolts going through the wings are close tolerance bolts and are hard to get in place.
While working on this part. Think twice, measure twice, and then redo it once more.
As these parts are matchdrilled, it will be very hard to get you some new pieces which fit as perfect as the ones you received do. So again... don't screw up here !
On DWG-11, one of the first tasks is to enlarge the holes for some snap bushings to 5/8inch. This is for SB625-7 snap bushings that will guide the rudder cables through the fuselage and also for some electric wiring passthrough to the back of the aircraft.
I started by using the step drill in the bench drill to enlarge the pilot holes on the center section sides. Watch carefully ! There are a lot of holes on this part. Check twice before lowering your drill bit.
The side bars are marked with a scribe during manufacturing as L Aft, R Aft, L Fwd and R Fwd. These are also matchdrilled in the factory so it's important to take the correct ones.
It's obvious that Fwd goes on the F-704A center section and Aft to the F-704B center section. Left and right are according to the seating position of the pilot looking forward.
Enlarging holes
Ready and snap bushings installed.
Then, carefully measure the location of the snap bushings on the inside of the F-704A and F-704B center section.
Drilled with pilot drill and then enlarged to 5/8 with the step drill under the bench drill.
Then, I deburred the F-782B and F-783B cover support ribs. These will support the fuel lines, passthrough electric wiring and take nutplates for the cover plate.
All bushings installed on the main parts.
The ones on the outside are just drilled. I didn't install bushings yet here because there will be some interference with the side supports and the plans tell you to grind down a bit on the bushings. I'll install them once the sides are rivetted on to find out the exact size.
