What happened
On August 16, 2015, at 11:13 UTC, a Mi-2 helicopter was participating in the "Heli-race" event during the 15th Helicopter World Championships at the EPZP aerodrome. As the pilot initiated the takeoff for the race, the powerful downwash from the aircraft's rotors caught a PVC start-line marker. The force of the airflow dislodged the marker from the ground, tearing the steel pins used to secure it from the turf.
The displaced PVC material was lifted into the main rotor system, causing fraying and damage. Additionally, one of the metal securing pins was blown into the tail rotor, resulting in five distinct impact points of damage. Following the incident, the competition was temporarily suspended to secure the area. After a 30-minute inspection of the takeoff site for foreign object damage (FOD) and the installation of a new, secured start line, the competition resumed. Following a mechanical inspection, the aircraft was cleared to continue participating in the championships.
The investigation
The PKBWL investigation focused on the interaction between the aircraft's rotor downwash and the ground equipment used for the competition. The investigators examined the stability of the start-line markers and the impact of the aerodynamic forces generated by the specific aircraft type involved in the event.
Findings
- The primary cause of the tail rotor damage was the dislodgement of a securing pin from the start-line marker due to the intense downwash produced during takeoff.
- A contributing factor was the fact that the pins had been driven into soft ground, which allowed the powerful downwash of the Mi-2—which is significantly stronger than that of other participating aircraft types—to lift the marker and its fasteners from the surface.
Safety action
To prevent a recurrence in future competitions, the event organizers committed to using longer, more deeply driven, and more densely spaced pins to secure all ground markings against wind and rotor downwash.