What was found
(DUCT SEAL BOOT) ENROUTE, THE CABIN ALTITUDE WARNING HORN SOUNDED ALERTING THE CREW THAT CABIN ALTITUDE WAS AT 10,000 FEET. WITH OUTFLOW VALVE CLOSED, CREW WAS UNABLE TO CONTROL CABIN ALTITUDE. CREW DESCENDED FLIGHT AND DIVERTED, WHERE THE FLIGHT LANDED WITHOUT FURTHER INCIDENT. NO EMERGENCY WAS DECLARED AND NO OXYGEN MASKS WERE DEPLOYED. MAINTENANCE RESECURED DUCT SEAL BOOT IN KEEL BEAM AREA. LEAK CHECK GOOD. ALSO, REPLACED FORWARD ENTRY DOOR LOWER HINGE FLAP SEAL. LEAK CHECK GOOD. PERFORMED LEAK DOWN RATE TEST PER MM. OPERATIONAL TEST SATISFACTORY.