Swiss Investigation of Jodel D 140 R Accident at Croix de Cœur (HB-SFR)

Incident Overview and Flight Details On July 19, 2016, a privately owned Jodel D 140 R, registration HB-SFR, was involved in an accident at the Croix de Cœur mountain landing site in the commune of Riddes, Valais, Switzerland. The aircraft, a single-engine, four-seat, low-wing monoplane with fixed landing gear and a tailwheel, was constructed in 1967 by Société Aéronautique Normande (S.A.N.) in France. It was imported to Switzerland in 1985 and returned to service in 2005. The aircraft was powered by a Lycoming IO-360-A1B6 engine. The flight originated from La Côte aerodrome (LSGP) at 09:50 local time. The pilot, a Swiss citizen born in 1944 holding an EASA Airline Transport Pilot Licence (ATPL(A)), was accompanied by one passenger. After 38 minutes of flight, the aircraft arrived at Croix de Cœur and completed two uneventful landings. Following a break, the aircraft took off again at approximately 11:40 for a third landing before returning to La Côte. ## Accident Sequence and Wreckage Findings At 11:43, the aircraft touched down at the very beginning of the landing site. The pilot described the initial contact with the ground as normal. Suddenly, the left main landing gear collapsed. The aircraft gradually turned to the left and completed a 120-degree rotation around its yaw axis. During this rotation, the main landing gear folded under the wing and fuselage. The aircraft traveled a total distance of 54 meters from the initial touchdown to its final position on the left side of the landing site. No fire occurred, and both occupants exited the aircraft under their own power without injury. Wreckage examination revealed damage to the propeller, wing undersides, and flaps. The left landing gear wheel axle fractured at the weld of the brake caliper mounting bracket. The left wheel was found approximately ten meters from the aircraft's final position. The left landing gear leg and sleeve folded backward, while the right landing gear folded toward the fuselage. The flaps were extended to approximately 50 degrees. The emergency locator transmitter did not activate, though the manual switch was in the 'ARM' position. ## Meteorological Conditions and Investigation The weather at the time of the accident was sunny with light winds. A north-easterly valley wind was present near the ground. Visibility was 10 km or more, with a wind from 035 degrees at 5 knots, gusting to 10 knots. The temperature was 17 °C with a dew point of 6 °C, and the QNH was 1021 hPa. The landing site is located at an altitude of 2180 m, with an average slope of 11 degrees. ## Probable Cause The accident was attributed to the embrittlement of the wheel axle, which led to the fracture of the left landing gear upon touchdown and an uncontrolled skid of the aircraft.