What was found
FLIGHT 5152 AIRCRAFT FAILED TO PRESSURIZE DURING CLIMBOUT OF CVG, AIRCRAFT RETURNED TO THE FIELD. REPLACED THE PRIMARY OUTFLOW VALVE.
As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
FLIGHT 5152 AIRCRAFT FAILED TO PRESSURIZE DURING CLIMBOUT OF CVG, AIRCRAFT RETURNED TO THE FIELD. REPLACED THE PRIMARY OUTFLOW VALVE.