As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AFTER TAKE OFF, THE AIRCRAFT WAS CLIMBING THROUGH 3000 FEET THE CREW NOTICED A LOSS OF PRESSURIZATION FOLLOWED BY A DOOR LIGHT AND VIBRATION IN THE RUDDER PEDALS. THE CREW CONTACTED ATC AND RETURNED TO PIT. MAINTENANCE INSPECTED AND FOUND THAT THE CARGO DOOR HAD COME OPEN, WITH NO DAMAGE TO THE DOOR OR AIRFRAME. MAINTENANCE RESECURED THE DOOR AND THE REPOSITION FLIGHT CONTINUED TO TYS.