What happened
On the morning of June 30, 2002, a Spring Bok ultralight, identified as 59-CER, was performing a series of touch-and-go landings at the Saint-Hilaire-sur-Helpe airfield. The pilot was preparing for a series of passenger flights scheduled for an aerial demonstration later that day.
During the first circuit, while flying a downwind leg for runway 09, the pilot received a radio transmission from an individual on the ground requesting that the engine power be reduced and that the aircraft land as soon as possible. As the aircraft continued on the downwind leg, the engine ceased operation. Unable to reach the runway, the pilot attempted an emergency landing in a nearby field approximately fifty meters short of the runway threshold. The aircraft subsequently struck a hedge bordering a pasture, resulting in damage to the aircraft.
The investigation
The investigation focused on the circumstances leading to the engine failure and the fueling process prior to the flight. It was established that before starting the engine, the pilot had replenished the aircraft's fuel using a canister intended for use during the day's aerial event.
At the time of refueling, the individual responsible for preparing the two-stroke fuel mixture had not yet arrived, meaning the oil had not been mixed with the gasoline. Furthermore, the investigators found that the fuel canisters lacked any distinctive markings that would allow the pilot to differentiate between pure gasoline and the required oil-gasoline mixture.