What was found
(CAN) DURING APPROACH TO BASE AT 2,500 THE NR 1 ENGINE INDICATED A FIRE CONDITION. ONCE ENGINE SECURED, (PER IAC) T-HANDLE INDICATION EXTINGUISHED. CONTINUED WITH CHECK LIST (DID NOT FIRE BOTTLES), FIRE INDICATION REAPPEARED (T-HANDLE LIGHT & BELL). FIRED BOTH BOTTLES ACCOMPLISHED SAFE EMERGENCY LANDING WITHOUT INCIDENT. NO ENGINE INSTRUMENT OR OTHER VISUAL INDICATIONS WERE OBSERVED, BUT DUE TO WEATHER COULD NOT VISUALLY OBSERVE NR 1 ENGINE NACELLE. INVESTIGATION FOUND FAILED CLOSED FIRE/OVERHEAT SENSOR SWITCH, INTERNAL WARNING SWITCH CLOSED AS MEASURED ACROSS PINS A & D.1343.0 HOURS/1841 CYCLES.