What happened
On May 1, 2014, a Robinson R44 Raven II helicopter, registration OK-SPW, was conducting a recreational flight near Sulice, Czech Republic. The flight, operated by HELITOM, s.r. and involving the pilot and three passengers, included a planned stop at a private landing site.
During the climb following the stop, the pilot noticed unusual resistance in the cyclic control. The pilot mistakenly identified this as a hydraulic system failure and, attempting to troubleshoot, toggled the hydraulic switch on the cyclic lever. The pilot then decided to perform an immediate emergency landing in a nearby field.
As the aircraft transitioned from forward flight to a hover over a field covered in approximately 50 cm of tall grain, the pilot struggled to maintain stability. The uneven terrain and the lack of visual reference points caused the right skid to strike the ground. In an attempt to correct the resulting pitch, the pilot applied excessive force to the controls, causing the helicopter to roll onto its right side. The impact of the main rotor blades with the tail boom and the ground resulted in the total destruction of the aircraft.
The investigation
An investigation by the ÚZPLN established that the hydraulic system had not suffered a technical failure. Instead, the system had been inadvertently deactivated, likely when the pilot accidentally bumped the switch while interacting with passengers during the previous stop.
The investigation examined the pilot's actions, noting that the pilot did not follow the flight manual's procedures for verifying the hydraulic system or managing the emergency. The investigation also reviewed the aircraft's condition, finding that the engine and mechanical components were functional prior to the impact, and that the damage to the airframe and rotor system was a direct result of the collision with the ground.
Findings
- The pilot misidentified the cause of the control resistance as a hydraulic failure.
- The hydraulic system was accidentally deactivated by the pilot during the flight.
- The pilot chose an unsuitable landing site characterized by a significant slope and tall crops that obscured ground references.
- The pilot's reaction to the aircraft's movement during the landing attempt was uncoordinated and involved excessive control inputs.
- The pilot failed to follow established procedures for handling a hydraulic system deactivation or an emergency landing.
- The aircraft was within its maximum takeoff weight and all mechanical systems were operational before the impact.