What happened
On March 24, 2009, a Piper PA-28-161 was conducting a VFR training flight near Bellechasse, Switzerland. The flight, part of a pilot training course, involved several simulated emergency landing exercises. During one such maneuver, the crew performed a power-idle approach followed by a go-around.
Approximately 20 to 3-0 seconds after applying full power during the climb, the engine experienced a sudden and significant power loss accompanied by heavy vibrations and a mechanical rattling sound. The instructor took control of the aircraft to navigate around obstacles, including trees and high-voltage power lines. While the instructor managed to execute a steep left turn to reach the Bellechasse airfield, the aircraft could not maintain sufficient altitude to clear the perimeter. The aircraft struck a pasture fence just before the runway threshold and slid approximately 400 meters into a field. There were no fatalities among the two occupants, though the aircraft sustained damage to the wing and spinner.
The investigation
SUST examined the technical condition of the Piper PA-28-161, the engine, and the meteorological conditions at the time of the accident. The investigation included a review of maintenance records, which showed that recent inspections had specifically checked the carburetor heat system, yet the defect remained undetected. Investigators also analyzed the weather, noting that temperatures and humidity levels were highly conducive to ice formation in the carburetor.
Findings
- The engine power loss was most likely caused by carburetor icing.
- The effectiveness of the carburetor heat system was significantly reduced due to the poor mechanical condition of the heat air door and box.
- Meteorological conditions, specifically a descent at idle power in moist air, favored the formation of ice.
- The instructor's decision to perform a steep, high-bank turn to avoid obstacles was a challenging maneuver that, while avoiding power lines, ultimately led to the collision with the fence.
Safety action
No specific safety recommendations were recorded in the provided report text.