What happened
On January 14, 2023, a Robinson R 22 BETA II helicopter, registration OK-TOM, was conducting flight training near Lanžhot, Czech Republic. The flight was part of an instructor training program, specifically focusing on navigation and practicing emergency procedures. During the session, the crew decided to practice a landing with a simulated tail rotor control failure. To simulate the malfunction, the instructor took control of the pedals, leaving the pilot to manage the aircraft using only the cyclic and collective controls.
After a successful initial landing using this method, the crew attempted a subsequent takeoff using the same procedure. As the helicopter began to lift off in the ground effect, the rear of the left skid made contact with the soft, grassy terrain. As the pilot increased collective to break ground contact, the aircraft began an uncontrolled, rapid rotation around its vertical axis. Despite the instructor's attempts to intervene with the pedals, the rotation could not be stopped. The aircraft completed approximately two rapid rotations before the tail boom and tail rotor struck the ground, leading to the destruction of the transmission shaft and the airframe. The helicopter came to rest on its left side. The crew members were uninjured.
The investigation
The ÚZPLN investigation focused on the sequence of events and the technical state of the aircraft. Investigators examined the wreckage and performed a technical analysis of the transmission and engine. The investigation established that the engine was functioning normally until the impact and that all mechanical components, including the tail rotor control systems, were fully functional prior to the accident. The investigation also reviewed the flight training syllabus and the crew's actions during the maneuver.
Findings
- The primary cause of the accident was an uncontrolled attempt to take off with a simulated tail rotor control failure, which was performed in violation of the flight manual.
- The training procedure used was methodologically inappropriate, as performing a takeoff with simulated control failures is highly dangerous and counterproductive.
- The pilot responded to the sudden, unusual movement of the aircraft with an inappropriate control input, leading to a loss of control.
- The soft terrain caused the left skid to sink, which, combined with the lack of tail rotor control, initiated the uncontrolled rotation.
- The crew's decision to perform this specific maneuver was made during the flight and did not align with established safety protocols for emergency procedure training.