Showplanes FB rear seatback

Question for those that built the Showplanes FB conversion.
Pretty sure I am on the right track but just making sure.
Regarding the Showplanes supplied composite top to the aft cockpit seatback, I can see where I will need to trim it narrower (roughly at the black line) so that it fits behind the F-833B seatback sides.


My main question is the connection to the seat structure. Once the composite piece is narrowed it will pick up the four rivet holes in the sides but only one of the rivets in the actual seatback.


Also, just assuming that I have it placed correctly on the seat structure I will need to trim the flange all the way around in order to clear the shoulder harness openings in the bulkhead.

Yes, trimming is definitely required. One rivet into the frame and throught the fiberglass, into the seat back is fine. You'll be putting rivets along the full width of the seat back top also, into the fiberglass seat top. Under this interface - along the top, I also used a West System structural adhesive and a little flox, or chopped cotton to help stiffen the plastic to prevent cracking of the fiberglass under the rivets. No cracks so far (5+ years). Roughen up the aluminum to help with adhesion.

This is how I did it. I was happy enough with the results, seems quite stiff when riveted.
I believe the earlier kits had the glass top as standard (mine is a -1, ally top). So there may be some tips or plans around.
The doubler strip in the bottom pics has slightly rolled edges to help it sit better.
The glass is captured between ally all round.
As Scott mentioned you will have to trim plenty. I also prep'd this before riveting, for pinholes and prime.
Paul.

Scott, Paul. Thanks for the info. Just making sure I wasn't headed down the rabbit hole of mistakes.

I have a friend who is quite good with composite work. He is storing a piece of equipment in my hangar. I told him his storage payment was to teach me how to work with composites. I figure this will be a good piece to learn the first steps on.