What happened
On May 25, 2005, a Robinson R22 helicopter was conducting a flight instruction session at Lelystad Airport. The flight involved an instructor and a student, for whom this was the very first helicopter lesson. After departing the airport, the instructor began transferring control of the aircraft to the student. During this transition, a warning light illuminated and an audible signal sounded, indicating that the rotor RPM was dropping. The instructor observed a rapid decrease in rotor speed on the tachometer and immediately took control to establish an autorotation. After stabilizing the aircraft, the instructor increased the engine RPM and continued the flight, assuming the student had accidentally closed the throttle.
Later in the flight, the crew attempted a hovering exercise. The instructor transferred control of the tail rotor, then the collective, and finally the cyclic to the student. Shortly after the student assumed control, the engine RPM dropped unexpectedly and rapidly. The helicopter entered a 180-degree spin and began to descend. Due to the low altitude, the instructor was unable to fully establish an autorotation. The aircraft struck the ground with excessive lateral velocity, causing the rotor blades to strike the earth and the helicopter to capsize.
The investigation
The investigation into the incident was based on data provided by the involved parties, as investigators did not attend the scene in person. The inquiry focused on the sequence of control transfers and the sudden loss of engine power during the hovering phase of the flight.
Findings
- The primary cause of the accident was that the student unintentionally closed the throttle while manipulating the collective lever.
- The instructor had been holding the throttle firmly during the initial transfer of the collective but may have lost focus after the cyclic controls were also handed over to the student.
- The low altitude at the time of the engine power loss prevented the instructor from successfully correcting the descent.
- There were no injuries to the two occupants, though the Robinson R22 sustained heavy damage.