What was found
DURING CRUISE, ENGINE FIRE ANNUNCIATOR ILLUMINATED FOR APPROX 3 SECONDS WITH WARNING HORN THEN EXTINGUISHED. THEN APPROX 10 SECONDS LATER IT OCCURRED AGAIN AND REPEATED THIS ABOUT EVERY 10-15 SECONDS. AFTER THE THIRD EVENT THE ANNUNCIATOR REMAINED ON. ALL ENGINE PARAMETERS WERE NORMAL AND THERE WAS NO SIGN OF FIRE OR THE SMELL OF SMOKE. DUE TO BEING HALFWAY BETWEEN THE DEPARTURE CITY AND ARRIVAL CITY THE DECISION WAS MADE TO DIVERT AND LAND. WHEN MAINTENANCE ARRIVED, THEY DISCOVERED THE LH AFT ENGINE FIRE DETECTION LOOP WAS BROKEN. LOOP WAS REPLACED AND OPS CHECKED GOOD