What happened
During the initial climbout phase of flight, the aircraft experienced an in-flight separation of its cabin door. The door opened while the airplane was airborne and subsequently detached from the fuselage. Following separation, the door impacted the empennage section of the aircraft. This impact resulted in substantial damage to the airframe.
The sequence of events began with a passenger closing the cabin door prior to departure or during pre-flight procedures. According to the report signed by the pilot in command, the closure was not verified as secure by the PIC. The official documentation explicitly noted that the door was not verified to be closed properly by the pilot in command.
The investigation
An examination of the incident focused on the status of the cabin door and the actions taken by the crew. The report indicated that no mechanical malfunctions were identified in reference to the flight systems or the door mechanism itself. The investigation highlighted a procedural gap regarding the verification of the door's latching status.
Findings
The primary factor contributing to this incident was the failure to verify the cabin door was securely latched. A passenger performed the action of closing the door, but the pilot in command did not confirm that the closure was complete or secure. This lack of verification allowed the door to open under aerodynamic loads during climbout.
Substantial damage occurred to the aircraft structure due to the impact with the empennage. The incident underscores the critical importance of positive confirmation for all exterior closures, particularly when non-crew members are involved in pre-flight tasks.