What happened
On March 8, 2015, a Robinson R44 RAVEN I, registration OK-ADT, was performing a landing on a private, paved area at the edge of the village of Prasek, near Nový Bydžov. The pilot had previously obtained permission from the landowner to use the site for landing.
During the approach from the north, the pilot had to clear a fence surrounding the facility. As the aircraft approached the landing spot, the pilot applied forward cyclic to compensate for a higher fuel load, causing the helicopter to land in a slightly aft-tilted attitude. The rear of the skid landing gear made initial contact with the ground. In response to the aircraft's movement, the pilot applied an instinctive and improper input to the cyclic control. This maneuver caused the rotor disk to tilt, resulting in the main rotor blade striking the tailboom.
The investigation
The ÚZPLN investigation examined the aircraft's maintenance history, the pilot's qualifications, and the sequence of the landing maneuver. The investigation confirmed that the aircraft was within its permitted weight and center of gravity limits and that all mechanical systems, including the engine and flight controls, were fully functional prior to the strike. The investigation also noted that the pilot did not report the accident to the authorities at the time of the occurrence.
Findings
- The pilot was fully qualified and medically fit for the flight.
- The aircraft was airworthy and had undergone all required maintenance.
- The primary cause of the accident was an inappropriate control input following the initial contact of the landing gear with the ground.
- The pilot's reaction to the unusual movement of the helicopter caused the rotor disk to deflect into the tailboom structure.
- The impact caused extensive damage to the tailboom, the tail rotor transmission, the tail rotor control rod, and the tail rotor protection, necessitating the replacement of these components.