What happened
On 5 January 1999, a Robinson R22 Beta, registration G-INTC, was conducting a private training flight at Halfpenny Green Airport. The flight involved a student pilot and an instructor performing engine-off landing practice. After several successful maneuvers, the student was tasked with managing a simulated engine failure at an altitude of 150 feet.
During the recovery phase of the maneuver, the rotor RPM decreased to 90%. Because the aircraft was experiencing a 25-knot headwind, the student anticipated that the rotor speed would stabilize during the landing flare. However, as the flare was initiated, the wind speed dropped abruptly. This caused the helicopter to descend rapidly. In an instinctive attempt to arrest the descent, the student increased the collective input, which further reduced the rotor RPM. Although the instructor took control of the aircraft, the high descent rate resulted in a heavy landing.
The investigation
The investigation examined the sequence of events leading to the impact and the mechanical response of the aircraft. It was established that the high landing forces, combined with the low rotor speed at the moment of impact, caused the main rotor to droop. This movement resulted in the rotor blades severing the tail boom. Following the impact, the helicopter yawed left and rolled onto its right side. The two crew members escaped through the broken windshield and sustained no injuries.
Findings
- The primary cause of the accident was the sudden reduction in headwind speed, which prevented the pilot from maintaining sufficient altitude to execute a go-around or transition to a hover.
- The instinctive application of the collective lever during the rapid descent contributed to the further decay of rotor RPM.