As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) ACFT RETURNED AFTER TAKEOFF WITH THE UPPER CABIN DOOR OPEN. NO FAULTS FOUND WITH DOOR LOCKING MECHANISM. DOOR UPPER FWD HINGE FOUND DAMAGED AND PULLED DUE TO BEING OPEN IN FLIGHT. SUSPECT THAT THE DOOR NOT LOCKED PROPERLY PRIOR TO TAKEOFF. UPPER DOOR ASSY REPLACED WITH SERVICEABLE DOOR AND ACFT RELEASED FOR SERVICE.