As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON CLIMBOUT FROM CVG, ACFT WOULD NOT PRESSURIZE. EMERGENCY DECLARED, ACFT RETURNED TO CVG LANDED SAFELY. INSPECTED BOTH OUTFLOW VALVES, PERFORMED BITE TEST OF CPAN 1 AND 2 NO DEFECTS NOTED. PRESSURIZED ACFT ON GROUND WITH NO DEFECTS NOTED.