What was found
DURING CLIMB OF THE ACFT AS FLIGHT TAI-593, THE PILOT REPORTED THAT THE OUTFLOW VLV BECAME UNCONTROLLABLE. THE SYS WAS RESET BY THE CREW, BUT NOT SUCCESS OBTAINED ON CONTROLLING CABIN V/S & HENCE, THE ACFT WAS RETURNED. AFTER AN UNEVENTFUL LANDING & IAW TSM 21-31-00-810-809-A, THE OUTFLOW VLV & THE CABIN PRESS CONTROLLER OF SYS 1 WERE REPLACED. THE PRESS CONTROL & MONITORING SYS OPERATIONAL TEST WAS PERFORMED IAW AMM 21-31-00-710-002 003 WITHOUT FAILURE MSG. AS A PRECAUTIONARY ACTION, A VERIFICATION FLIGHT WAS CARRIED OUT WITHOUT THE FAILURE REPRODUCTION. AFTER THE DESCRIBED CORRECTIVE ACTIONS WERE TAKEN, THE ACFT WAS RETURNED TO SERVICE.