What was found
(CAN) DURING CRUISE, CREW NOTED CABIN ALTITUDE WARNING. UNABLE TO CLOSE OUTFLOW VALVE EITHER ELECTRICALLY OR MANUALLY. EMERGENCY DESCENT PERFORMED, OXYGEN MASKS DROPPED. OUTFLOW VALVE WOULD CLOSE TO THE .2500 POSITION ON GAUGE. ATTEMPTED TO CLOSE VALVE MANUALLY AT 10000FT (OAT +13 DEG C), NO RESPONSE. VALVE CLOSED SUCCESSFULLY AFTER 10 MIN. ON INSP FOUND PORTABLE WATER LEAKING AT FITTING AND FITTING PARTLY SEPARATED WITH WIGGENS COUPLING OPEN. UPON INSP OF REMOVED COUPLING FOUND CRACKED. (TC NR 20080305004)