Front Shoulder. The front seat belt mount points are birch plywood embedded in the foam, 1/16th aluminum under that, with a total of 7 (original 4 + plans revision 3) plies over the top. The work on the front shoulder points was done October 17-20 of 2005. The front seat has clearly visible hard points and it was straightforward to locate the nutplate and drill an appropriate hole through the top of the front shoulder support.

Front Lap. The front seat lap belt attach points were done 12/7/05. (See those entries.) The outside attach point are plywood hard points, aluminum angle, then 7 plies BID and uni, then drilled for bolts through the lower longeron. The front center attach is tubing in the seat back

Rear Shoulder. Set into the center section of the wing spar cap are the rear shoulder harness mounts, hardpoints made from spruce and embedded into the foam. Over the top of the hard points go 4 layers of unidirectional fiberglass layup. This was then reinforced with a plans change - add more plies. Here, both wing and center section spar were built by Dennis Oelmann and purchased by the prior builder. I energized a high lumen LED panel inside the spar and was able to see the wood inserts as shadowed areas. I confirmed this with a tap test - tap, tap goes the quarter, and you can "see it with your ears". The rear seat photos below are from another builder - Dennis did the work but failed to provide photos for the log. Dennis put the hard points at 7.25" and 12.75" from the center line. Plans locations are 5.25" and 12.5" from center line, while Aerocad spars use 5.5" and 14". I'll go ahead with the existing hardpoints, and modify if indicated. No nutplate - drill through the hard points and use an AN4 bolt to secure the belt hardware.

Rear lap. The outside attach point are plywood hard points, aluminum angle, then 7 plies of alternate BID and uni, then drilled for bolts through the lower longeron. The rear center attach is a 2" length of 20204 tubing is laid across the heat duct and covered with 7 plies uni and then 2 plies BID. After paint I drilled out the tube. Test fitting AN4 bolts I found AN4-32a was the length that fits the washers, seat belt end and lock nut.

Using auto racing belts. I ordered a set of new-in-box but out-of-date racing belts in a a 6-point configuration. 3" wide shoulder and lap belts, 2" leg loops. Blue that conveniently matches the upholstry fabric.
- The 6 points are lap, shoulder and crotch. After some trial and error, I'm going with 4-point, and not using the cratch straps.
- I'll install the rear belts for the certification, but most flying will be solor or 2-place with significant baggage capacity. I might make the rear lap belts only - lots of space between rear occupant and the back of the front seat. I have the parts ready to install if I change my mind.
- Auto racing belts are good for 24 months from date of maunfacture, while the same material in an aviation belt can be used until it fails to flex. The auto belts are assumed to live on a planet with 24/7 sunshine, while the aviation product lives in a world of perpetual darkness. It makes sense to change seat belts when changing hoses.
- I used a basting stich for the initial fit, then bought and learned how to use a sewing machine. There was a delay as I attempted to restore a Singer 237 (1960's), then a current model made the job doable. The formula for stiching seat belts uses the strength of the webbing, the strength of the thread and number of stiches per inch and inches of stitching. By using a triple stich with "overlock", the webbing is calculated to break (6000 lbs) before the stiches give way.