What was found
DURING CRUISE, NR 1 ENGINE FIRE WARNING LIGHT CAME ON CAUSED BY B-LOOP FIRE INDICATION. ENGINE WAS SHUT DOWN IAW FIRE CHECK LIST. 2211 FLT MANUAL, VOL I. BOTH FIRE BOTTLES DISCHARGED. THERE WAS NO VISUAL INDICATION OF FIRE. A-LOOP WAS PREVIOUSLY PLACARDED INOP OUT OF MIAMI. AFTER FURTHER TROUBLESHOOTING, MAINTENANCE REPLACED AFT FIRE WARNING DETECTOR. SYSTEM CHECK NORMAL PER MM 26-21-00. (X)