What happened
On February 28, 2004, at approximately 13:00 UTC, a Rotorway Exec 162F helicopter, registration CS-XHC, was conducting a training flight at Benavente aerodrome. The flight was intended as a transition/refresher mission for the pilot, who had not operated this specific type of single-rotor aircraft in recent months. An instructor was on board to supervise the maneuvers.
During the second takeoff attempt of the session, the aircraft was positioned on runway 36. Due to the lateral slope of the runway for water drainage, the helicopter was resting with a slight leftward tilt. To compensate for this inclination, the pilot applied right cyclic control. At the same time, a 10-knot wind was blowing from the west (left side of the aircraft).
As the pilot increased collective power, the left skid lifted from the ground while the right skid remained in contact with the runway. The combination of the pilot's rightward cyclic input and the wind pushing against the aircraft's large lateral surface area caused the helicopter to pivot around the right skid. Before the crew could react, the main rotor blades struck the ground, causing the engine to stall and the aircraft to slide approximately three meters before coming to rest on its right side. Both occupants escaped the aircraft without injury.
The investigation
The GPIAAF investigation examined the aircraft, the flight history, and the environmental conditions at the time of the accident. The investigators reviewed the pilot's experience, noting that while the pilot had extensive fixed-wing experience, he had only 88 hours of experience in single-rotor helicopters, with very little time flown in the 90 days prior to the accident.
The investigation also analyzed the physical evidence at the scene, including the deformation of the main rotor blades and the damage to the cabin and tail stabilizer. The investigators concluded that the aircraft was airworthy and that the maintenance program was being correctly followed. The meteorological conditions were found to be within VFR limits, with good visibility and light winds.
Findings
- The primary cause of the accident was the inadequate compensation for the terrain slope and the crosswind effect during the takeoff maneuver.
- The pilot's decision to apply right cyclic to correct for the leftward tilt of the aircraft on the sloped runway, combined with the wind from the left, created a pivot point on the right skid.
- The Rotorway Exec 162F has a large lateral surface area and a wide skid width, making it highly sensitive to crosswinds.
- The suddenness of the aircraft's roll prevented the crew from implementing corrective actions.
- The impact of the rotor blades with the ground caused the engine to stop and resulted in structural damage to the main rotor, cabin, and tail boom.