Assembling the F-705 Bulkhead

The F-705 bulkhead supports the seat backs, strengthens the open cockpit and provides the attachment for the rear wing spar. I first marked a lengthwise centerline on the rear face of the F-705B center section bar. I then located and clamped the F-705B, the F-605C Bar Doublers and the F-705H Spacers to the F-705A Rear Spar Attach Bulkhead. I drilled the assembly using the prepunched holes in the F-705A as a guide.

Then I drilled the F-634 seat belt anchors to the F-705 lower bulkhead assembly. One of each pair of anchors was drilled first. It was then bolted to the F-705A, then a 3/16″ shim was put between it and the other anchor and the three pieces were clamped together. The flange of the unbolted anchor was then clamped to the bulkhead. Drill the anchor using the prepunched hole in the bulkhead as a guide.

In some cases, the flange of the seat belt anchor would come close to an adjoining rivet or bolt hole. So I had to grind or file the flange of the seat belt anchor to allow for bolt or rivet heads as necessary. I was careful to preserve a 2 diameter edge allowance from the center of the anchor bolt hole to the edge of the anchor flange.

Finally I disassembled and prepared the F-705A lower bulkhead for riveting and drilled the snap bushing holes to full size.

Time: 6 hours