What happened
On Wednesday, May 15, 2002, at approximately 15:00 local time, a Bell 47 G2 helicopter, registration F-GLID, was conducting a flight test at an unpaved runway near Chartres, France. The flight was part of a private helicopter pilot license examination involving an instructor and a student pilot.
After one hour of flight time, the instructor directed the student to perform an autorotation maneuver with the engine at idle power. The student pilot initiated a stabilized descent and began the flare. Observing that the student was initiating the maneuver at too high an altitude, the instructor physically blocked the collective pitch lever with his hand to prevent the student from applying premature upward support.
While the student successfully leveled the aircraft, they subsequently applied the collective to execute the second flare. During this phase of the autorotation, the helicopter made a hard landing on the ground in a level attitude without sliding. Upon inspection, the instructor discovered that the main rotor blades had struck the tail boom, resulting in the tail boom being severed near the tail rotor.
The investigation
The investigation focused on the sequence of the autorotation maneuver and the physical intervention of the instructor. Investigators examined the flight parameters, though the exact altitude at which the first flare began and the aircraft's velocity during the maneuver could not be precisely determined. The investigation also reviewed the experience levels of the crew, noting the instructor was highly experienced with over 1,280 flight hours, while the student pilot had 96 hours on type.
Findings
- The primary cause of the accident was the incomplete intervention of the instructor during the flight maneuver.
- The physical blocking of the collective lever by the instructor, intended to correct the student's altitude management, contributed to the subsequent improper execution of the second flare phase.