What was found
AIR TURN BACK- CLIMBING THROUGH 4000 FT, NR 4 ENGINE FIRE INDICATION WITH BELL AND MASTER FIRE WARNING; LIGHT ON. NR 4 ENGINE NACELLE TEMP A AND B AT 9.5. ENGINE FIRE CHECKLIST PERFORMED. NR 4 ENGINE SHUTDOWN. ON ARRIVAL, FOUND NR 4 ENGINE NR 4 "C" DUCT BLOWOUT PANEL OPEN, NACELLE STRUT PRESSURE RELIEF DOORS OPEN, NO ACTUAL FIRE NOTED. FOUND HP VALVE DAMAGED, FOUND "C" DUCT WITH SIGN OF OVERHEAT DAMAGE, HIGH STAGE VALVE HARNESS DAMAGE, PRESSURE RELIEF VALVE DAMAGE AND PRV SENSE LINE DISCONNECTED. REPLACED PRV AND CHECKS OK, REPLACED TRANSLATING COWL, REPLACED HIGH STAGE VALVE, HIGH STAGE VALVE HARNESS AND CHECKED OK.