Bolted center bearing assembly to rear spar; torqued bolts to 23 in/ft. Riveted HS-810-1 reinforcement angle, HS-814-1 splice angle and HS-00003 spar doublers to front spars. Riveted HS-00005 and HS-00006 ribs to front spars. Some difficulties and mistakes. Drilled out 4 rivets, but did no damage. Mocked up skeleton again, for the last time before disassembly for skinning.