What happened
On 27 November 1999, an AS365N2 helicopter, registration G-MLTY, was performing a public transport flight near Burnley. After completing two short shuttle flights involving various passengers, the aircraft departed for a return journey to Leeds. During the final approach to Leeds Bradford Airport, approximately 11 miles from the runway, the left middle cabin door suddenly detached and fell into the Leeds/Liverpool canal.
The pilot immediately notified Air Traffic Control of the incident. To prevent objects from being sucked out of the cabin, the pilot maintained a speed of 70 knots while applying significant yaw. Despite the loss of the door, the remainder of the approach and the landing were completed safely with no injuries to the crew.
The investigation
Investigators examined the door mechanism and the cockpit environment. The middle doors on this aircraft model are hinged at the front and latched at the rear, controlled by jettison handles located on the door posts. In a standard configuration, these handles are protected by clear, breakable plastic covers and secured with snap wires.
On G-MLTY, which featured a VIP internal trim, the plastic covers were held in place by screws. It was noted that the instructional labels for the jettison handles were missing from the door posts, likely omitted during a previous interior refurbishment.
Upon inspecting the left middle door's jettison handle, investigators found that the snap wire had been broken, even though the plastic cover remained intact. Further inquiries revealed that as the pilot was exiting the helicopter to open the passenger doors for the previous group of passengers, he had accidentally operated the jettison lever.