What happened
On November 18, 2003, an Ecureuil AS 350 B3, registration F-GODJ, was conducting an off-line flight check near Albertville. The flight was being supervised by an examiner who was evaluating a pilot from Héliand SA. As part of the training, the examiner instructed the pilot to simulate a fuel regulation failure by transitioning the FADEC system to manual mode.
While the aircraft was in level flight at approximately 2,500 feet, the crew experienced intense vertical vibrations. The examiner took control of the aircraft and initiated an autorotation procedure. During the descent, the heavy vibrations persisted. As the helicopter approached the ground in a field, it touched down with a low vertical rate but high horizontal speed. The skids dug into the soft, moist soil, causing the aircraft to skid and eventually flip onto its back, resulting in the total destruction of the airframe.
The investigation
Investigators examined the wreckage and the onboard monitoring systems, including the FADEC and the Vehicle and Engine Monitoring System (VEMD). The analysis of the wreckage showed that the main rotor blades and the STARFLEX starhead were subjected to high energy, indicating the rotor was still rotating at high speed at the moment of impact. The investigation also focused on the sequence of engine malfunctions recorded by the aircraft's electronic systems.
Findings
- The flight crew initiated a simulated engine failure by switching the fuel regulation from "Auto" to "Man".
- The aircraft experienced multiple simultaneous failures, including collective pitch failure, loss of turbine speed (NF) data, and engine oil pressure warnings.
- The failure to return the "Auto - Man" selector to the "Auto" position contributed to the inability to maintain stable engine regulation.
- The heavy vibrations were a direct result of the engine's inability to maintain stable parameters following the manual mode activation and subsequent system errors.
- The high horizontal speed during touchdown and the soft ground conditions led to the skids digging in, causing the aircraft to capsize.