What was found
EXECUTED AN AIR TURN BACK DUE TO THE LOSS OF CABIN PRESSURIZATION AT FL 320 WITH CABIN OXYGEN MASKS AUTOMATICALLY ACTIVATED, DROPPED. EMERGENCY RETURN TO DEPARTURE WAS DECLARED AND LANDED UNEVENTFULLY. REPLACED ENGINE-2 BLEED, SYS OVER PRESSURE VALVE, PRESSURE REGULATOR VALVE AND TEMP LIMIT THERMOSTAT. CLEARED PREVIOUS MEL ON AIR PACK-1, THE REPLACEMENT OF THE PACK-1 FCV, FLOW CONTROL VALVE.