Fatal stall and impact involving Zenair CH601 in New Caledonia

Casualties unknown • l’Île des Pins Moué, FR

A pilot was killed when a microlight experienced a progressive engine power loss during takeoff, leading to a stall and collision during a turn at Île des Pins Moué.

What happened

On October 25, 2018, a Zenair CH601 (registration 988AC) departed from the Île des Pins Moué aerodrome in New Caledonia for local circuit flights. The flight was intended to verify the aircraft's performance following recent maintenance and repairs, which included a vertical stabilizer replacement and a 100-hour inspection.

During the takeoff roll on runway 10, the engine RPM began to decrease gradually. While the pilot continued the takeoff, the engine power dropped from an initial 5,200 RPM to approximately 3,300 RPM. About one minute after liftoff, while the aircraft was at an altitude of roughly 40 meters, the pilot initiated a right-hand turn. During this maneuver, the aircraft entered a stall and collided with the ground near the aerodrome, resulting in the death of the pilot and the destruction of the aircraft.

The investigation

The BEA investigation utilized radio communications, an onboard camera, and witness testimonies to reconstruct the flight sequence. The investigation focused on the engine's performance and the aircraft's flight parameters. Analysis of the onboard camera allowed investigators to evaluate the aircraft's pitch and roll angles, while spectral analysis of the audio provided engine RPM data.

Investigators examined the wreckage and found that the flight controls were intact prior to impact and the propeller was rotating upon hitting the trees. Components including the carburetors, fuel filter, mechanical fuel pump, and fuel lines were analyzed, but no specific abnormalities were found in the fuel system. The investigation could not definitively determine the cause of the engine's power reduction.

Findings

  • The primary cause of the accident was a progressive loss of engine power during the takeoff roll, which went undetected by the pilot because the reduction in RPM was too gradual to be easily noticed by ear.
  • The pilot attempted a turnaround with a 30-degree bank angle while maintaining a high pitch attitude, a maneuver that was incompatible with the aircraft's reduced airspeed.
  • The aircraft was not equipped with a stall warning system.
  • The difficulty in managing a partial power loss, rather than a total engine failure, contributed to the loss of control.

Probable cause

A gradual and subtle reduction in engine power during the takeoff roll led to the aircraft operating at a much lower power setting than required for climb. This loss of performance, combined with a high-pitch turn maneuver, resulted in an aerodynamic stall and subsequent ground impact.

Frequently asked questions

What happened in the 2018-10-25 l’ULM ZENAIR - CH601 accident near l’Île des Pins Moué, FR?

A pilot was killed when a microlight experienced a progressive engine power loss during takeoff, leading to a stall and collision during a turn at Île des Pins Moué.

What aircraft was involved and where did it happen?

The accident on 2018-10-25 involved a l’ULM ZENAIR - CH601, registration 988AC, at l’Île des Pins Moué, FR.

What was the probable cause of the accident?

A gradual and subtle reduction in engine power during the takeoff roll led to the aircraft operating at a much lower power setting than required for climb. This loss of performance, combined with a high-pitch turn maneuver, resulted in an aerodynamic stall and subsequent ground impact.

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