What happened
The accident occurred during a flight training session involving a practice demonstration of an autorotation landing. The certified flight instructor (CFI) was initially controlling the aircraft while the student pilot monitored and prepared to take over. As the helicopter approached the ground for the simulated landing, the student pilot took control of the cyclic stick.
According to the instructor's account, the student applied excessive forward or lateral cyclic input just prior to touchdown. This abrupt control input caused the helicopter to roll sharply to the right. The tail rotor blade struck tall grass on the ground, which arrested its rotation and contributed to the loss of directional control. The force of the impact with the vegetation caused the main rotor system to contact the ground, resulting in the helicopter rolling over completely onto its side.
The investigation
Examination of the site revealed that the terrain consisted of high grass, which played a critical role in the final moments of the accident sequence. The tail rotor struck this vegetation, preventing normal yaw control and facilitating the rollover. No mechanical failures were reported as contributing factors; the event was attributed entirely to pilot input during the landing phase.
Findings
The primary factor leading to the accident was the student pilot's excessive cyclic control input during the critical low-altitude phase of the autorotation landing. The timing of this input, just before touchdown, left insufficient altitude or time for recovery. The presence of high grass at the landing site exacerbated the situation by striking the tail rotor, which prevented corrective action and ensured the helicopter rolled onto its side.
Safety message
Student pilots must be closely monitored during autorotation practice to ensure smooth control inputs. Excessive cyclic movement near the ground can lead to loss of control, especially when combined with environmental factors like tall grass that may interfere with tail rotor effectiveness.