What was found
A RIVET HEAD WAS FOUND MISSING ON THE DOUBLER ON THE RT SIDE OF THE VERTICAL FIN AT THE TAILBOOM/ VERTICAL FIN TRANSITION. FURTHER INSP REVEALED A CRACK IN THE VERTICAL FIN FWD BULKHEAD/ SPAR STRUCTURE, STARTING FROM THE TOP RT AFT RECEPTACLE HOLE FOR THE TRANSITION COVER, RUNNING TO THE EDGE OF THE FLANGE. ANOTHER CRACK WAS FOUND, STARTING ON THE OTHER SIDE OF THE HOLE, RUNNING TOWARDS THE FLANGE RADIUS. DYE PENETRANT VERIFIED THE CRACKS. THE RIVET WAS REPLACED AND A REQUEST WAS SUBMITTED TO AEC FOR REPAIR INSTRUCTIONS.