As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ACFT OPERATING ON A MAINTENANCE CHECK FLIGHT FOR PRESSURIZATION CHECK. THE ACFT FAILED THE MAINTENANCE CHECK AND A PAN PAN WAS DECLARED WITH ATC. CPCS CONTROLLER REPLACED IAW AMM 21-31-01, AC PACKS AND DUCTS INSPECTED AND LEAK CHECKED, CABIN PRESSURIZATION FUNCTION CHECK CARRIED OUT IAW AMM 21-31-00. PRESSURIZED TO 4.5 NO FAULTS.