What happened
On 8 April 2019, a Jodel D117A, registration G-AZII, was performing private flight circuits at Full Sutton Airfield, York. The pilot, a left forearm amputee, utilized a bespoke prosthetic adapter to operate the aircraft's ailerons and elevator. This adapter was attached to the control column via an interference push-fit mechanism.
During the fourth circuit, while the aircraft was on final approach and the pilot was attempting to flare, the prosthetic adapter became disconnected from the control column. This caused the aircraft to revert to a shallow, nose-down attitude. The aircraft subsequently struck the ground heavily, causing the landing gear to collapse and resulting in damage to the engine, propeller, and lower engine cowl. The pilot sustained no injuries during the event.
The investigation
The AAIB investigation examined the construction of the prosthetic adapter, which consisted of a carbon fibre/epently tube with a high-tensile bolt and an aviation rose joint. While the pilot had used this interface for over 230 hours, the connection relied solely on an interference fit without any secondary mechanical securing device.
Investigators also reviewed the medical certification process. Although the pilot had successfully passed a medical flight test (MFT) and met the existing requirements for a Light Aircraft Pilot’s Licence with an 'APL' limitation, the investigation found that the robustness of the interface between the prosthesis and the aircraft controls had not been evaluated by a qualified engineer. The investigation noted that the pilot's approach focused on modifying the prosthesis rather than the aircraft, which meant the setup was not subject to standard aircraft modification oversight.
Findings
- The heavy landing occurred because the pilot was unable to regain control of the aircraft after the prosthetic adapter detached during the flare.
- The connection between the adapter and the control column was solely reliant on an interference push-fit.
- There was no formal engineering assessment of the forces or the security of the interface between the prosthesis and the flight controls.
- The pilot had met all existing medical certification requirements at the time of the accident.