What was found
EN ROUTE FROM KWI TO AVB, THE FLIGHT CREW HEARD CREW HEARD A BANG FROM THE TURBO COMPRESSOR BAY ARE FOLLOWED BY LOSS OF CABIN PRESSURIZATION. THE FLIGHT CREW FOLLOWED COMPANY EMERGENCY PROCEDURES AND DESCENTED TO A SAFE ALTITUDE. THE FLIGHT CONTINUED TO AVB FOR AN UNEVENTFUL LANDING. MAINTENANCE INSPECTED THE AIRCRAFT LOCATING AN UNSECURED DUCT AT THE NUMBER FOUR TURBO COMPRESSOR CHECK VALVE. MAINTENANCE SECURED THE DUCT AND PERFORMED A SUCCESSFUL OPERATIONAL TEST. THE AIRCRAFT WAS RETURNED TO SERVICE. (M)