What was found
DURING HEAVY CHECK, REPORTED RT WING RIB 10 EXTENSION IS CRACKED GOING FWD AND AFT FROM UPPER SKIN HI-LOCK HOLE, THIRD FROM AFT SIDE, CRACK LENGTH .320 FROM AFT EDGE OF HOLE,.480 FROM FWD EDGE OF HOLE. MX R & R RIB 10 EXTENSION IAW SRM 51-43-02, SRM 51-43-03. PERFORMED FCBS 57-10-00-005 NO ADDITIONAL INSPECTIONS REQUIRED. PN 170-32161-612/RIB 10. MAJOR REPAIR, ACFT REMAINS FOR COMPLETION OF HEAVY CHECK.