What happened
On July 10, 1999, a Brändly-Cherry BX-2, registration HB-YCV, departed from the Ecuvillens aerodrome in Switzerland for a flight to Clermont-Ferrand. After completing pre-flight checks and refueling, the pilot and a passenger began their takeoff roll on runway 10. Witnesses observed the aircraft accelerating with a flat attitude, but shortly after leaving the runway, the aircraft pitched up without gaining significant altitude. During this maneuver, the aircraft appeared to lose lift on the right wing, followed by a sudden right-hand turn that led to a crash approximately 300 meters east of the airfield.
Upon impact, the aircraft was destroyed, and the two occupants sustained one fatality and one serious injury. The wreckage was found scattered across a field, with the occupants positioned inverted within the fuselage. Despite the rupture of the fuel tank and subsequent minor fuel pollution, no fire occurred.
The investigation
Investigators examined the wreckage of the HB-YCV and the mechanical components of the Continental TCM A-65 engine. Tests on the magnetos and spark plugs revealed no functional defects, and the carburetor was found in the full-power position. The aircraft's weight at takeoff was approximately 540 kg, which was within the maximum allowable limit of 550 kg.
Technical inspections of the aileron linkages, control cables, and pulleys showed no evidence of prior failure or improper maintenance. The investigation also noted that the landing gear remained extended and locked, and the flaps were retracted at the time of the accident. Meteorological data indicated a prevailing bise wind, with gusts reaching up so high as to potentially affect the aircraft's stability.
Findings
- The aircraft was operating near its maximum allowable weight, which limits the rate of climb.
- The pilot's initial pitch-up maneuver increased aerodynamic drag, hindering the aircraft's ability to accelerate.
- The failure to retract the landing gear further increased drag, preventing the aircraft from reaching a stabilized climb speed.
- A gust of bise wind likely caused an asymmetric increase in lift, increasing the angle of attack on the windward side while causing the leeward wing to stall.
- The low altitude and low airspeed prevented the pilot from recovering control before ground impact.