What was found
HAD FIRE WARNING NR 4 ENGINE WHEN SETTING CLIMB POWER. COMPLETED QRH EMERG FIRE PROCEDURE. FIRED INBOARD AGENT. ATTEMPTED TO FIRE OUTBOARD BUT NO INDICATION OF DISCHARGE NR 3 LIGHT TESTS, NR 4 LIGHT NO-TEST. REMOVED AND REPLACED NR 4 ENGINE AFT UPPER, FORWARD UPPER, AND LOWER FIRE SENSING ELEMENTS. ALSO, REPAIRED BROKEN WIRE ON AT CONNECTOR OF LOW PRESSURE SWITCH. REPLACED BOTH INBOARD AND OUTBOARD FIRE BOTTLES.