As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKEOFF LEFT PACK CONTROL VALVE WOULD NOT MAINTAIN CABIN ALTITUDE OF 10000 FEET WITH AIRCRAFT AT FL250 AND RIGHT PACK OFF. RIGHT PACK CONTROL VALVE WILL NOT MAINTAIN CABIN ALTITUDE OF 10000 FEET WITH AIRCRAFT AT FL 250 AND LEFT PACK OFF. CREW RETURNED AIRCRAFT TO PHIK AND LANDED WITHOUT INCIDENT. AN INSPECTION IS ON GOING AND INFORMATION WILL BE PROVIDED AS SOON AS IT IS AVAILABLE.