As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CABIN PRESSURE CONTROL SYSTEM MALFUNCTIONED IN CLIMB. FAILED IN STANDBY MODE TO FULL CABIN DESCENT, SWITCHED TO MANUAL DC FAILED OPS PER AOM VOL 1. REMOVED AND REPLACED OUTFLOW VALVE PER MM. OPS CHECK GOOD PER GROUND OPS PROCEDURE. (M)