What was found
ENROUTE FROM LAX TO TOL, DURING CRUISE THE NUMBER FOUR FIRE WARNING LIGHT ILLUMINATED ACCOMPANIED BY THE WARNING BELL. THE FLIGHT CREW FOLLOWED COMPANY EMERGENCY PROCEDURES, SECURED THE ENGINE AND DISCHARGED BOTH BOTTLES. THE FLIGHT RETURNED TO LAX FOR AN UNEVENTFUL LANDING. MAINTENANCE INSPECTED THE ENGINE WITH NO EVIDENCE OF A FIRE. FURTHER INSPECTION REVEALED THREE FIRE SENSEING ELEMENTS DEFECTIVE AND A ELECTRICAL CONNECTOR. MAINTENANCE REPLACED THE ELEMENTS AND ELECTRICAL CONNECTOR AND PERFORMED A SUCCESSFUL OPERATIONAL CHECK. THE AIRCRAFT WAS RETURNED TO SERVICE.