What was found
WHILE AT CRUISE, HEARD A LOUD BANG FROM REAR BAY. CREW FELT LARGE PRESSURE BUMP AND CABIN WAS CLIMBING AT 2500+ FPM. CABIN ALTITUDE WARNING AND HORN CAME ON. INSPECTED REAR BAY BLEED AIR AND DUCT SYSTEMS. FOUND DUCT SEPARATED UPSTREAM FROM WATER SEPARATOR. INSPECTED CLAMP AND FOUND WORN AREA ON CLAMP. REMOVED AND REPLACED DUCT CLAMP AND INSTALLED ON SLEEVE. PERFORMED SYSTEM OPS & LEAK CHECKS, AS WELL AS PRESSURIZATION CHECKS. ALL CHECKED NORMAL. ALL INDICATIONS ARE NORMAL IAW AMM 21-10-15, 21-10-95, AND 21-30-16.