What was found
(CAN) ON A FLIGHT DURING CLIMB OUT AT FL 110 AND CLEARED FOR FL150 A (CABIN ALT) EICAS MESSAGE POSTED. THE CREW OBSERVED THAT CABIN ALTITUDE WAS CLIMBING IN AN UNUSUAL HIGH RATE. WHEN CABIN ALTITUDE REACHED 10000 FEET CREW DECIDED TO CONTROL IN MANUAL MODE. NO RESPONSED WAS NOTED. NOW GOR A MASTER WARNING DUE TO CABIN ALTITUDE HIGHER THAN 10000 FEET AND O2 MASKS DROPPED AND CREW PUT THEIR OWN MASKS ON. CREW DECIDED TO LEVEL OFF AT 15000 FEET AND FERRY FLOWN THE AIRCRAFT AT LOW LEVEL. ALSO OUTFLOW VALVE P/N 103664-2 WAS REPLACED AS BOTH VALVES FAILED THE TO PASS THE AMM TESTING. (TC NR 20060403003)