As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLT 417 - PIT-MDT - CLIMBING THROUGH 17,000 FEET, CABIN ALTITUDE CONTROL WHEEL WENT FULL CLOSED AND STARTED TO CHATTER AND VIBRATE. SELECTED STANDBY WITH NO CHANGE. WENT TO MANUAL AND REGAINED CONTROL OF CABIN PRESSURE. RETURNED TO PIT. FOUND NR 1 PRESSURIZATION CONTROLLER NOT OPERATING. REPLACED CONTROLLER. (M)