Accident to the Robin DR401 Ecoflyer registered F-HVAN on 22/06/2017 at Darois

The three persons on board the aircraft were two ACPV instructors and a member of the flying club who was also an independent sales representative for Robin Aircraft. The flights out of Dijon-Darois aerodrome were to finalize the purchase of the aircraft before ferrying it to Vannes-Meucon aerodrome where the flying club was based.

The two pilots accompanied by the passenger boarded the DR401, with the passenger taking the rear seat, in order to familiarize themselves with the diesel engine that they had little knowledge of and to validate the check-list procedures and parameters drawn up by the club based on the supplement to the manufacturer’s flight manual.

They decided to carry out several aerodrome circuits on runway 20, making a full-stop landing each time. At the end of the first runway circuit, the two pilots changed roles: the pilot in the left seat became the pilot-in-command and the pilot in the right seat was responsible for reading and validating the check-list.

During the second runway circuit, at the beginning of the downwind leg, they observed a slight variation in the engine rpm before it returned to the nominal value. After making the full-stop landing, the pilot-in-command decided to carry out a new runway circuit. During the third take-off, at around 400 ft, the engine suddenly shut down. No warning was activated. The pilot in the right seat, who had more experience, took the controls and indicated that he was going to carry out a forced landing in a field with high crops to the left of the flight path. At the same time, the pilot in the left seat tried to identify the cause of the failure.

On touching down, the pilot considered that he would not be able to bring the aircraft to a halt before a row of trees situated at the end of the field. He pushed on the right pedal with force to try and stop the aeroplane more quickly, which violently yawed to the right. The passenger, who had released his seatbelt, was projected through the rear left window. The aeroplane came to a halt around 20 m further on. The two pilots quickly evacuated the aircraft after having shut down the systems and took care of the passenger.

While assembling the aeroplane and engine and in particular, the electrical wiring, the power supply lines of the two engine computer channels (ECU A and B) were not connected in accordance with the engine manufacturer’s latest instructions: the connection made resulted in a 5 A circuit breaker being mounted in series on the power line of each channel.

In normal operation, each of the ECU channels uses between 5 and 7 A. The circuit breaker’s threshold and time to tripping depend on the intensity of the current and the ambient temperature.

The day of the accident, the outside air temperature was high and this threshold had decreased. It was exceeded on the power line of ECU A after the second take-off. Due to the erroneous connection, ECU A was no longer powered by the main battery or the alternator, or the back-up battery and the FADEC A light on the warning panel could not light up.

ECU B took over control of the engine and the change in channel generated a temporary variation in engine rpm without activating the warning. The pilot who had the controls, the second pilot in the right seat and the passenger attributed this variation to an aerological phenomenon and decided to continue the flight.

On the third take-off, during the climb, the power supply to the second channel of the engine computer (ECU B) was cut off for the same reasons as for channel A and the engine shut down.

The pilot in the right seat, who was more experienced, took the controls and carried out a forced landing in a field of high crops.