As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ON TAKEOFF, THE AIRCRAFT WOULD NOT PRESSURIZE ACCOMPANIED BY A LOUD BANG AND THE NR 3 TURBO COMPRESSOR STALLING. THE FLIGHT RETURNED TO LPLA. MAINTENANCE FOUND THE FORWARD ACCESSORY COMPARTMENT DOOR AJAR. THE DOOR WAS RESEATED AND A GROUND PRESSURIZATION CHECK WAS ACCOMPLISHED. THE TURBO COMPRESSOR DUCTING WAS CHECKED WITH NO DEFECTS FOUND.