As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE CREW DIVERTED THE AIRCRAFT TO CHS AFTER THE NR 1 ENGINE SHOWED A MOMENTARY FIRE INDICATION, WHICH EXTINGUISHED ON IT'S OWN. THE THROTTLE WAS BROUGHT TO IDLE AND NO EXTINGUISHING AGENT BOTTLES WERE DISCHARGED. MAINTENANCE PERFORMED A TEST OF THE FIRE WARNING SYSTEM AND ALL CHECKS WERE GOOD. ALL FIRE WARNING LOOP RESISTANCES ARE WITHIN MM LIMITS. AN ENGINE RUN-UP WAS PERFORMED AND ALL PNEUMATIC DUCTS WERE CHECKED, NO TROUBLE FOUND. THE FDCU WAS REPLACED AND THE FINAL FIRE WARNING TEST WAS SATISFACTORY.