Prepped and primed all the center bulkhead parts. It was 100% humidity this morning but the forecast said it was going to burn off. It didn't. It was still very humid when I sprayed and the primer just would not dry. Finally did and started assembly in the afternoon once the sun had finally come out. Really just need to avoid priming on humid days. Assembled the foreword and aft seat support brackets and installed the nut plates for the seat supports and uprights. Installed the screws for the bulkheads and seat supports but have started riveting yet. Most will need to be bucked. 2/27: worked on aft center bulkhead a little. Primed the countersunk holes in the spar and installed the nut plates. Then installed and torqued all the AN bolts through the spar. Inserted the -4 rivets in their holes just to make sure alignment was still good. 2/28: riveted all the -4s on the aft bulkhead and then fabricated the wear strip, carefully measured the centerlines, clamped and drilled it. Riveted in place and I think it good. Aft bulkhead done. Riveted forward bulkhead. It's done too. Good night in the garage.