What was found
EN ROUTE TOL TO BFI, THE NR 4 ENGINE FIRE WARNING SOUNDED WITH NUMBER 4 HIGH STAGE BLEED VALVE SELECTED TO HIGH. NR 4 BLEED VALVE WAS SELECTED TO LOW AND FIRE WARNING EXTINGUSHED. FLIGHT CONTINUED TO BFI FOR AN UNEVENTFUL LANDING. MAINTENANCE INSPECTED THE ENGINE BLEED DUCTS AND FOUND A HIGH STAGE BLEED VALVE CLAMP LOOSE. THE CLAMP WAS SECURED. A SUCCESSFUL ENGINE RUN WAS ACCOMPLISHED TO TEST THE SYSTEMS AND THE AIRCRAFT WAS RETURNED TO SERVICE.