What happened
On 4 October 2023, an AS355F1 helicopter, registration G-BOSN, was conducting a commercial sightseeing tour of London with five passengers on board. Approximately 20 minutes after departure, both doors on the right side of the aircraft opened unexpectedly while in flight. The pilot observed that the rear door had swung open and was being held in a fully open position by the airflow, while the forward door had also become ajar.
Fearing that the rear door might detach from the airframe, the pilot decided to perform an immediate landing at the nearest available location, which was Gunnersbury Park. There were no injuries to the crew or passengers during the incident.
The investigation
Following the landing, the pilot inspected the aircraft and identified minor damage to the right rear cabin door, including a crack in the window. The investigation established that the window crack was caused by the door striking the hinge of the baggage compartment as it swung backward.
The pilot noted that the forward door was difficult to secure from a seated position, which may have contributed to it not being properly fastened. Furthermore, the pilot could not confirm that the locking pins on the rear door had been correctly positioned prior to takeoff.