What happened
On July 31, 2013, at approximately 16:30 UTC, a Robinson R44 Raven I, registration OK-KLK, was performing a recreational flight from Bohuňovice Airport (LKBO) to Kroměříž (LKKM) and back. The flight involved the pilot and two passengers.
Following pre-flight preparations, the pilot initiated a vertical takeoff from the asphalt apron in front of a hangar. Rather than utilizing the available runway space to establish forward airspeed, the pilot attempted to climb directly over obstacles. At an altitude of approximately 8 meters AGL, the aircraft was struck by a sudden wind gust, causing it to yaw to the left.
In an attempt to correct the deviation and avoid obstacles, the pilot applied right pedal and increased collective pitch. This maneuver caused the helicopter to enter a right-hand rotation. As the aircraft continued to spin, the pilot applied forward cyclic to move away from the obstacles, which inadvertently contributed to a loss of rotor RPM and diminished tail rotor effectiveness. The helicopter completed approximately three rotations in a descending spiral before impacting the grass of runway 07 with significant force. The impact resulted in the destruction of the aircraft.
The investigation
The ÚZPLN investigation examined the aircraft's technical condition, the pilot's experience, meteorological data, and video evidence from industrial cameras on the airfield. The cameras captured the entire sequence, from the initial vertical climb to the uncontrolled rotation and final impact.
Technical inspections of the Robinson R44 Raven I confirmed that all control mechanisms, including the engine and transmission, were fully functional prior to the crash. The investigation established that the damage to the airframe, including the separation of the tail boom and destruction of the rotor blades, was solely the result of the high-impact ground contact. Meteorological reports confirmed the presence of wind gusts of up to 22 knots in the area.