As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING DESCENT MAIN CARGO FIRE WARNING CAME ON. CONDUCTED A VISUAL INSPECTION, NO EVIDENCE OF SMOKE NOR FIRE NOTICED. TRANSFERRED TO DMI 22720 'B' LOOP NR 21 IN ACCORDING WITH MEL 26-16-2. PLACARD INSTALLED. REMOVED AND REPLACED NR 5 SMOKE DETECTOR CAGE IN ACCORDING WITH MAINTENANCE MANUAL 26-16-01 AND OPERATION CHECKED OK IN ACCORDING WITH MAINTENANCE MANUAL 26-10-00. CLEARED DMI 22720 AND PLACARD REMOVED.