What happened
On March 23, 2001, a Schleicher ASK-16 motor glider, registration HB-2038, departed from Samedan Airport for a flight toward Mollis. Shortly after takeoff, at an altitude of approximately 20 meters, the aircraft experienced a significant loss of engine power. Although the air traffic controller queried the pilot regarding engine difficulties, the pilot initially reported no problems. Minutes later, the engine ceased operation entirely, causing the aircraft to enter a spin. The motor glider crashed into a wooded area near the Celerina bobsleigh run, striking a rock that forced the engine into the cockpit. The impact resulted in one fatality (the passenger) and one serious injury (the pilot).
The investigation
Investigators examined the wreckage and the engine components to determine the cause of the power loss. The investigation revealed that the engine had stopped at the moment of impact. Mechanical analysis of the Limbach L2-00 EB1 engine identified significant issues within the fuel system. Specifically, the fuel filter contained heavy deposits of dirt and contaminants. Furthermore, the mechanical fuel pump was found to be malfunctioning; the pump's connecting rod was not operating in its correct position, leading to abnormal wear on the camshaft. The engine's combustion chamber showed signs of a lean fuel mixture, consistent with insufficient fuel delivery.
Findings
- The primary cause of the accident was the loss of control of the aircraft following an engine failure.
- The engine failure was likely caused by a malfunction of the mechanical fuel pump and significant contamination within the fuel filter.
- The aircraft was flying in difficult meteorological conditions, characterized by a strong southwest wind that produced turbulence and downdrafts.
- The choice of flight path contributed to the accident, as the pilot's route through the area was not appropriate for the prevailing weather conditions.
- The aircraft's low rate of climb during the initial ascent, exacerbated by the high density altitude and wind conditions, left little margin for recovery once the engine failed.