What happened
On April 16, 2003, a privately owned Jodel D 119 (amateur-built) was performing a return flight from the Col du Palet altisurface to Annecy. During the flight, the pilot attempted to retract the aircraft's skis. While the left main ski retracted successfully, the right main ski remained in the lowered position. Despite several attempts to rectify the situation, the right ski failed to retract.
The crew evaluated alternative landing sites at La Rosière and Megève. However, due to unfavorable wind conditions at La Rosière and the fact that the Megève runway had been cleared of snow, the pilot opted to land at the unpaved runway at Annecy. The pilot performed a precautionary landing at approximately 90 km/h. During the landing roll, the aircraft slid for about 100 meters before the lowered right ski made contact with the dry, uneven ground. This contact caused the aircraft to pitch forward onto its nose, resulting in the aircraft coming to rest on its back. There were no fatalities among the two persons on board, and both occupants evacuated the aircraft without difficulty.
The investigation
The investigation focused on the mechanical failure of the ski control system. Technical examination of the aircraft revealed that the micro-switch responsible for detecting the compressed position of the right actuator was defective. This component is critical to the operation of the system, as it provides the electrical signal to the relay to power the ski retraction process until the ski reaches its fully upright position.
Findings
- The primary cause of the accident was a malfunction of a micro-switch within the ski control system.
- The failure of this micro-switch prevented the right main ski from retracting, forcing the pilot to execute a precautionary landing with the skis in the lowered position.
- The uneven, dry surface of the unpaved runway contributed to the aircraft's nose-over when the extended ski caught the ground.