What happened
On March 22, 2003, a Robinson R2/2 Beta helicopter, registration PH-JGS, was conducting a training flight at Lelystad Airport. The flight crew, consisting of an instructor and a student, were performing specialized maneuvers designed to simulate a tail rotor control failure, commonly known as "pedalless" landings. During these exercises, the instructor intentionally locks the pedals to prevent the student from using the anti-torque controls, forcing the pilot to manage the aircraft using only the cyclic and collective.
After the instructor had demonstrated the maneuver twice on a flat grass strip, the student attempted the landing. The landing was executed roughly, causing the left skid to strike the ground first. Although the instructor attempted to intervene, the aircraft's longitudinal axis was not aligned with its direction of travel. This misalignment, combined with the resistance of the grass surface, triggered a rapid roll to the left. The helicopter came to a halt on its left side, resulting in heavy damage to the aircraft. The instructor sustained light injuries, while the student remained uninjured.
The investigation
The investigation, which utilized internal reports from the flight school, focused on the mechanics of the "pedalless" landing and the environmental factors involved. Investigators examined the physics of the maneuver, noting that as power is reduced during the final approach, the aerodynamic effects of the vertical stabilizer decrease, causing the nose to yaw. The investigation also reviewed the suitability of using a grass surface for such high-risk maneuvers.
Findings
- The primary cause of the accident was a dynamic rollover caused by the aircraft's longitudinal axis not being aligned with its direction of movement during touchdown.
- The use of a grass surface increased the risk, as the uneven and soft terrain contributed to the sudden engagement of the left skid.
- The instructor's intervention occurred too late to prevent the rolling motion once the left skid made contact with the ground.
- The maneuver itself, while valuable for training emergency procedures, carries inherent risks when performed on non-paved surfaces.
Safety action
While the investigation concluded that practicing pedalless landings is beneficial for pilot proficiency, it suggested that the risks could be mitigated by performing these maneuvers on hard, flat surfaces. If a paved surface is unavailable, the exercise should ideally be terminated approximately one meter above the ground to avoid the physical risks associated with ground contact on soft or uneven terrain.