As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE FLIGHT CREW REPORTED AFTER TAKEOFF PRESSURIZATION FAILS WITH CABIN RAT CLIMB ABOVE 1000 FT/MIN UNTIL POWER IS REDUCED BELOW 65% N2. THE MAINTENANCE PROVIDER TROUBLESHOT AND FOUND THE NO2 ENGINE MIXING VALVE NOT OPERATING PROPERLY. THE MIXING VALVE WAS REMOVED AND AN OVERHAULED VALVE INSTALLED OPS CHECKS WERE SATISFACTORY AND THE AIRCRAFT WAS RETURNED TO SERVICE.