What happened
On 8 August 2007, a DA40D Diamond Star, registration G-JKMG, was conducting a sales demonstration flight at Chichester Goodwood Airfield. During the taxi phase of the flight, the front canopy had been left unlatched to improve ventilation, which triggered a red DOOR OPEN warning on the Garmin G1000 avionics panel. Although the canopy was closed before takeoff, the crew failed to notice that the warning message remained active.
While the aircraft was at approximately 700 ft, the pilot attempted to reach for the door to address the warning. This action caused the rear passenger door to swing open. As the door moved, the hinges retaining it to the airframe failed, causing the door to detach from the aircraft. The detached component moved over the fuselage and struck the right horizontal stabiliser, causing significant damage. Despite the impact, the crew continued the circuit and landed the aircraft safely. There were no injuries to the pilot or the passenger.
The investigation
The investigation examined the mechanical operation of the DA40 passenger door, which is a composite, upward-opening design. The door is held in place by two hinges and a gas spring strut, and is secured in the closed position by two locking bolts. The investigation established that the forward locking bolt interacts with a microswitch to clear the cockpit warning message. The investigation also reviewed the pilot's actions regarding the unlatched canopy and the failure to monitor the avionics warning panel during the pre-takeoff phase.