As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ABOUT 5 MINUTES INTO CRUISE AT 31,000 FT, CABIN ALTITUDE WARNING SOUNDS CABIN ALTITUDE AT 10,000 FEET AND CLIMBING. CONTROL REQUIRED BY ASE OF AUTO 2 SELECTION. AIRCRAFT RETURNED TO DEPARTURE STATION. REPLACED NR 1 CABIN PRESSURE CONTROLLER. OPS CHECKED SYSTEM GOOD. (M)