What happened
On September 15, 2003, at 17:30, a Bell 47 G2 helicopter, registered F-GGLB, was conducting a training flight near Aubérive, France. The flight was part of a preparation session for a student pilot's private helicopter pilot license test. During the flight, the instructor initiated a series of exercises over a clear field of alfalfa, simulating an engine failure while the aircraft was in a low-altitude hover, approximately one meter above the ground. To simulate the failure, the instructor reduced power toward idle.
As the power decreased, the student pilot reacted by lowering the collective pitch lever. This action was consistent with procedures for entering autorotation from an altitude above ground effect, rather than maintaining control during a low-altitude hover failure. The aircraft made contact with the ground, landing on its left skid, which subsequently failed. The main rotor blades struck the ground, causing the helicopter to come to rest on its left side, resulting in heavy damage to the aircraft. No injuries were reported among the two occupants.
The investigation
The investigation focused on the sequence of control inputs during the simulated engine failure. The instructor had placed a hand on the collective lever to assist in maintaining aircraft stability during the maneuver. Investigators examined the flight conditions, which were noted as CAVOK with an 8-knot wind, and the experience levels of the crew, which included an experienced instructor and a student pilot with 113 total flight hours.
Findings
- The primary cause of the accident was student pilot confusion regarding the correct control inputs required for the specific flight phase.
- The student applied the procedure intended for an engine failure occurring above ground effect, which involved lowering the collective pitch.
- The extremely low altitude at the start of the exercise left the instructor with insufficient time or margin to intervene and prevent the impact with the terrain.