Accident to the Robin DR400-120 registered F-GSBN on 04/04/2019 at Chavenay Villepreux aerodrome (Yvelines)

Note: The following information is primarily based on the pilot's statement. This information has not been independently validated by the BEA.

This is a courtesy translation by the BEA of the Final Report on the Safety Investigation. As accurate as the translation may be, the original text in French is the work of reference.

1 - History of the flight

At the end of a dual-command flight on a runway circuit with his instructor, the student pilot dropped the instructor off at the foot of the control tower and resumed taxiing to holding point 23 in order to undertake a solo flight. Once cleared by the controller, the student pilot lined up at the end of the runway[1] and then took off, gradually applying power. After around a hundred metres, the plane started gradually veering to the left. The student pilot was unable to control this yaw movement and decided to abort take-off by reducing power and then braking. When the aircraft was nearly at a complete stop, the pilot felt an impact on reaching the runway edge at taxiway A4 (see figure 2). He interpreted this as the left main landing gear wheel running over a hole in the grass surface of the runway. As a precaution, he decided to abort the flight and went back to the aero club parking area. Taxiing was not a problem. The nose wheel's response to the rudder pedal inputs was satisfactory. Once he had stopped in the parking area, the student pilot noticed that the left wing was damaged at rib 8 (see figure 1). This deformation was caused by an impact with a frangible sign on the edge of taxiway A4.

2 - Additional information

2.1 Pilot information

The student pilot had logged 45 flight hours and was making his second solo flight (1^st solo flight in July 2018 after 30 flight hours with an instructor). His last dual-command flight was three days earlier.

2.2 Meteorological information

Wind 190/06 kt, CAVOK, temperature 11°C, QNH 1009.

2.3 Aircraft information

The DR400 was examined by the aero club’s mechanic at the end of the flight. No anomalies were found. The pressure measurement of the nose gear shock absorber was in accordance with the manufacturer's recommendations.

The yaw control design includes a device that makes rudder pedal inputs on the nose gear ineffective once the aircraft is airborne. This lock is activated when the nose gear shock absorber is not compressed.

To take account of this, the flight manual states:

• Do not take weight off the nose wheel to make it easier to stay on the centreline,
• Take off positively at 90 - 100 km/h.

2.4 Video sequence

For this flight, the student pilot had installed a digital camera high up inside the aircraft. It was in operation at the time of take-off. Alignment and application of power were carried out without hurrying.

However, the film shows that rotation was performed prematurely. It can also be seen that the student pilot applied very little input on the right rudder pedal when the aircraft veered to the left.

3 - Lessons and conclusion

When taking off from a grass runway, the pilot may be tempted to take weight off the nose gear to reduce vibrations.

If rotation occurs too early, the pilot may lose the ability to steer the nose gear wheel. Because it is still subject to the secondary effects of the engine (helical slipstream and torque effect from propeller), the aircraft will have a tendency to veer left. However, the pilot can still operate the rudder, but the deflection has to be greater than normal.

The 4 kt crosswind component, not sufficient to cause a significant wind-vane effect (orientation into the wind), helped to accentuate this phenomenon, though it did not on its own play a decisive role in the runway veer-off.