This letter from the PFA, the British version of the EAA, concerning seatbelt installation was sent to Pietenpol builders in the UK.
The front harness support they talk about looks like this when installed
and here is a shot of the rear shoulder harness attachment points
Bill Rewey attached his front shoulder harness to a strap between the upper cabain supports
Oscar Zuniga Front Cockpit Shoulder Harness Attach Point
This is the shoulder harness attach point that I fabricated for the passenger cockpit on NX41CC. It follows a detail and concept that I saw in the BPA Newsletter but I tweaked things a bit. The essential part is the clamp on the cabane X-brace wires. I took two hardwood (ash) disks, clamped them together in a fixture and drilled a hole right through the center, through the joining line, on the drill press. Then I rotated the two pieces so that the groove on each disk captured one of the X-brace wires, measured and drilled two through-holes for the legs of a stainless steel U-bolt (hardware store), painted it, put some black electrical tape on the X-brace wires where they crossed, and assembled the whole thing.
On the backside you can see that I used a piece of flat
stainless to back the nuts up, then used stainless locking nuts to hold the
whole thing together.
My shoulder harnesses are the Y-type with a single attach point, so they work fine with this single point of attachment. Not sure how this would work with individual shoulder harnesses. Oh, and pay no attention to the V-groove that is cut in the top of the wooden disks... when flying solo it is simply used as a sighting point for homing in on my targets ;o)
Here is the setup that Corky had on the airplane originally. A piece of cable was run between tabs at the top attach points of the cabanes and the shoulder harness was clipped to the cable. It may have been just a wee bit more comfortable for the front passenger since it put the apex of the Y a bit farther from the neck, but either setup will work. I'll fly the new setup for a while and see if it obstructs my forward vision or creates any other problems, and I've left the attach tabs for the other setup in place in case I decide to go back to the cable rather than this U-bolt setup.