As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT, MASTER CAUTION FIRE WARNING AND BELL ACTIVATED INTERMITTENTLY. MAINTENANCE TESTED THE MAIN DECK SMOKE DETECTOR, LOWER CARGO FIRE DETECTOR, APU FIRE TEST, AND ENGINE A AND B LOOPS, ALL TESTED NORMAL. PROBLEM WAS NOT DUPLICATED. OKAY FOR SERVICE.