What was found
DURING CLIMBOUT, THE NR 1 ENGINE FIRE WARNING ACTIVATED WITH EPR GOING FROM 1.94 TO 1.8 AND EGT AT RED LINE. CREW DECLARED A YELLOW EMERGENCY, NR 1 ENGINE WAS SHUT DOWN, AND THE FLIGHT WAS RETURNED TO DTW. AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND 13TH STAGE SADDLE DUCT BLOWN WITH HOLE IN ENGINE COWL. REPLACED DUCT AND UPPER COWLING ASSEMBLY, OPERATIONAL CHECK NORMAL ON ENGINE RUN.