What was found
(CAN)DURING CLIMB AT 4,000 FT RIGHT ENGINE FIRE WARNING ILLUMINATED WITH BELL AND BOTH LOOP LIGHTS ON. ENGINE SHUT DOWN, FIRE CEASED AFTER AGENT 1 DISCHARGED. MAINTENANCE INVESTIGATION REVEALED ENGINE TO P YLON 13TH STAGE DUCT FAILURE AT CLAMP CONNECTION POINT. NEW DUCT AND CLAMP INSTALLED, #1 FIRE EXTINGUISHER BOTTLE REPLACED AND ENGINE GROUND RUN CARRIED OUT.