What was found
(CAN) DURING FLIGHT, NR 3 ENGINE FIRE WARNING INDICATION WAS ACTIVATED. BELL WAS INTERMITTENT BUT BECAME A LITTLE MORE STEADY. EMERGENCY PROCEDURES WERE INITIATED AND NR 3 ENGINE WAS SHUTDOWN. FIRE HANDLE WAS PULLED BUT NOT TO RELEASE EXTINGUISHING AGENT. ATC WAS NOTIFIED. AIRCRAFT LANDED WITHOUT INCIDENT WITH EMERGENCY VEHICLES ON SITE. AIRCRAFT WAS SHUTDOWN. MTCE ACCESSED THE SITUATION. AN ELECTRICAL SHORT WAS FOUND IN THE NR 3 ENGINE FIRE LOOP SYSTEM. THE AIRCRAFT WAS RUN UP WITH NO FURTHER PROBLEMS. THE AIRCRAFT WAS RELEASED. NO FAULT DURING SUBSEQUENT FLIGHT.