What happened
On July 16, 2017, an I.C.P. Savannah VG ultralight, registration 2AEQ, was performing aerial work involving banner towing near Propriano, France. The pilot departed from the private Capo di Feno airfield at approximately 15:15 local time.
During the flight, the pilot notified air traffic control that they were experiencing control issues and intended to return to the base to release the banner. The pilot reported difficulty with roll control, noting a sensation that the central control mechanism had failed, though pitch and yaw remained functional. After successfully releasing the banner, the pilot attempted a landing circuit. However, a second failure occurred during the final turn, resulting in a total loss of both roll and pitch control. The aircraft struck the ground approximately 100 meters short of the runway threshold with high horizontal speed and a nose-down, left-wing-low attitude, resulting in the death of the pilot and the destruction of the aircraft.
The investigation
The investigation focused on the structural integrity of the flight control system, specifically the optional dual-control setup installed on 2AEQ. Investigators examined the wreckage and found that while the rudder controls remained continuous, there were significant discontinuities in the roll axis. Specifically, the flaperon control actuator was broken, and the rivets connecting the control linkage to the surfaces had been torn away.
Crucially, the investigation identified that both attachments for the optional dual-control system on the airframe had failed due to fatigue. To confirm this, the BEA performed a metallurgical examination on a similar inter-stick tube taken from another aircraft. This examination revealed transgranular cracks at the weld toes, proving that the fatigue failure was not an isolated incident but a systemic issue with the SC155 attachment design.
Findings
- The primary cause of the accident was the fatigue failure of both attachments of the optional dual-control system.
- The initial failure of one attachment allowed the pilot to maintain pitch control but introduced significant play in the roll axis. The pilot's decision to return to base was likely influenced by the temporary stability provided by the remaining attachment.
- The subsequent failure of the second attachment during the landing circuit rendered the aircraft uncontrollable.
- The aircraft was not equipped with a ballistic parachute at the time of the accident, as it had been removed for scheduled maintenance, which prevented the pilot from mitigating the impact.