What was found
PRESSURIZATION SAFETY VALVE SHOWED OPEN & AMBER ON ECAM. ACFT WOULD NOT PRESSURIZE MORE THAN 2.1 DIFFERENTIAL, CABIN CLIMBED TO 10,000 RETURNED. PRESSURIZED ACFT AGAIN AND FOUND NR 1 SAFETY VALVE FAULTY, REMOVED AND REPLACED THE SAFETY VALVE IAW MM 21-31-15-04. SAFETY VALVE OPERATES NORMAL, ACFT PRESSURIZATION OPERATES NORMAL IAW MM 21-31-00-05.