What was found
CREW REPORTED LOSING CABIN PRESSURE ON DESCENT. FAULTS INDICATE CABIN PRESSURE SAFETY VALVE HAS FAILED OPEN, ECAM 21-31, CABIN PRESSURE LOW DIFFERENTIAL PRESSURE, ECAM 21-31 CABIN PRESSURE SAFETY VALVE, REFER TO TSM 21-31-00-810-808, TSM 21-31-00-810-810. ACCOMPLISHED FAULT ISOLATION IAW TSM 21-31-00-801-808-A. FOUND SAFETY VALVE SYMBOL CLOSED. REPLACED SAFETY VALVE 7-HL PRECAUTIONARY. OPS CHECKED GOOD.