What was found
AIRCRAFT RETURNED TO ORD DUE TO A CABIN PRESSURE PROBLEM. *S/D* THE AIRFLOW CONTROL VALVES WERE INOPERATIVE. REPLACED LEFT AND RIGHT VALVES.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
AIRCRAFT RETURNED TO ORD DUE TO A CABIN PRESSURE PROBLEM. *S/D* THE AIRFLOW CONTROL VALVES WERE INOPERATIVE. REPLACED LEFT AND RIGHT VALVES.