As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW REPORTED THAT THE AIRCRAFT WOULD NOT MAINTAIN PRESSURIZATION DURING FLIGHT. THE CREW RETURNED TO FIELD AND LANDED WITHOUT FURTHER INCIDENT. MAINTENANCE VERIFIED THAT THE MANUAL PRESSURIZATION SYSTEM WAS OPERATIVE AND DEFERRED THE AUTO PRESSURIZATION SYSTEM. THE DEFERRAL WAS CLEARED LATER THAT DAY WHEN THE PRESSURIZATION DIGITAL CONTROLLER WAS REPLACED. OPERATIONAL CHECKS WERE GOOD WITH NO FURTHER DEFECTS NOTED.