What was found
DURING CRUISE FLIGHT, PILOT NOTICED THE RT FIRE PULL, HANDLE ILLUMINATED, THE PILOT FOLLOWED THE CHECKLIST PROCEDURES IN THE FLIGHT MANUAL & PERFORMED AN INFLIGHT SHUT DOWN OF THE RT ENG. THE PILOT DECLARED AN EMER, RETURNED & LANDED WITHOUT INCIDENT. INSPECTED THE RT ENG & FOUND NO EVIDENCE OF A FIRE. TROUBLESHOOTING REVEALED AN EXHAUST LEAK FROM THE RT INBD EXHAUST STACK MOUNTING FLANGE THAT WAS DIRECTING HOT EXHAUST ON THE FIRE LOOP. REMOVED STACK & REINSTALLED WITH NEW HARDWARE. GND RUNS & AN OPERATIONAL CHECK FLIGHT WERE PERFORMED. FIRE DETECTION INDICATION ON THE RT ENG WAS NORMAL.