What was found
DURING CLIMBOUT, GOT LEFT ENGINE FIRE INDICATIONS. BELL, SHUT OFF SW, T-HANDLE, MASTER WARNING, EICAS MSG. SHUT DOWN AND SECURED ENGINE. CREW PERFORMED AN AIR TURN BACK TO OAK WHERE THE AIRCRAFT LANDED AT APPROXIMATELY 285,000 LBS AS A RESULT OF AN EMERGENCY RETURN. AIRCRAFT LANDED WITH A LOW SINK RATE. AIRCRAFT LANDED WITH OUT INCIDENT. REPLACED NR 1 ENGINE LOOP 2 FIRE DETECT CARD M682 AND FIRE/OVERHEAT CARD IAW B767 AMM 26-10-01-4. OVERWEIGHT LANDING INSP. COMPLIED WITH PER B767 MM 05-51-35-2. NO DEFECTS NOTED. TROUBLESHOOTING STILL IN PROGRESS AT THIS TIME. REMOVED AND REPLACED BROKEN SPRING ON RECOUP DUCT IAW CF6MM 71-00-02. NO DEFECTS NOTED ON ENGINE RUN.