Clecoed and riveted left and right bulkhead flanges to bulkhead. Clecoed left and right stub receptacles and stub spar receptacle supports to the bulkhead, as directed. Removed protective vinyl, deburred, and prepared bulkhead doublers, as directed. Clecoed and riveted bulkhead doublers to both ends of the bulkhead, the stub spar receptacles, and stub spar supports. Riveted flanges of the bulkhead doublers to each other. Clecoed and riveted the control column mount assemblies and their associated one leg nutplates to the bulkhead. Clecoed and riveted four nutplates to sloped flanges of each control column mount assembly. Rmoved protective vinyl, deburred, and prepared bulkhead doublers, as directed. Riveted 17 nutplates to the bulkhead.