What happened
On 19 February 2022, a Robinson R44 Cadet, registration F-HOHE, was conducting a local flight near the Étangs de Valojoulx in France. The pilot, accompanied by one passenger, departed from Saint-Crépin et Carlucet aerodrome. Approximately 45 minutes into the flight, the pilot observed variations in engine speed and, suspecting an engine malfunction, decided to perform an immediate landing.
The pilot identified a dyke separating two aquaculture lakes as a suitable landing site, a location previously used for training exercises. Upon landing on the dyke, the engine parameters appeared to return to normal. However, after roughly ten seconds of stability, the right skid of the helicopter sank into the loose, peaty soil, causing the aircraft to slide backward. In an attempt to regain a hover, the pilot applied a significant input to the collective pitch. This maneuver failed to overcome the resistance of the stuck skid, resulting in a loss of control. The helicopter tipped to the right and forward, striking the water at the edge of the lake. The impact resulted in two injuries (the pilot and passenger) and the destruction of the aircraft.
The investigation
The BEA examined the wreckage, the landing site, and the pilot's statements. The investigation focused on the ground conditions of the dyke, which consisted of a 25-meter-wide area of loose peat and grass. Investigators noted a 50 cm deep depression in the ground, consistent with the heel of the skid sinking into the soft substrate. The investigation also reviewed the pilot's flight history and the mechanical state of the Robinson R44 prior to the accident.
Findings
- The pilot's decision to land was driven by perceived engine speed fluctuations, which the pilot associated with a previous occurrence on the same aircraft.
- The landing site consisted of loose, unstable soil that allowed the right skid to sink.
- The right skid became stuck in the soft soil due to a suction effect, which prevented the pilot from successfully re-establishing a hover.
- An excessive collective pitch input during the attempt to lift off contributed to the loss of control and the subsequent impact with the water.