What happened
On November 12, 2011, a Hughes 369E helicopter, registration G-WOOW, was conducting a private sightseeing flight over the island of Mallorca. The flight, which included the pilot and one passenger, initially proceeded normally through the island's northern regions. The occupants were specifically interested in viewing a property located near the valley of Es Ratjoli.
As the aircraft reached the Comellar de Sa Guixeria valley, the pilot transitioned into a hover at an altitude of approximately 80 meters above the ground. During this maneuver, the aircraft suddenly became unstable. The helicopter began a rapid descent, performing two complete right-hand turns about its vertical axis. Within approximately seven seconds of the initial instability, the aircraft struck a mountainside in the La Trapa wooded area. The impact triggered a fire that destroyed the aircraft and burned approximately 450 m2 of vegetation. Both occupants sustained fatal injuries.
The investigation
The CIAIAC investigation examined the aircraft's maintenance records, flight data from a recovered GPS unit, and video footage provided by an eyewitness. The investigation also included a spectral analysis of the engine and rotor sounds recorded by a nearby film crew.
Investigators analyzed the aircraft's weight and balance, confirming it was within manufacturer limits. Maintenance records showed that a 50-hour inspection had been missed by 16 hours, though this was not considered a contributing factor. The investigation also reviewed the meteorological conditions, noting moderate winds with gusts up entailing a significant relative wind angle against the tail rotor. Toxicological analysis of the pilot's blood showed an alcohol content of 0.76 g/l, though investigators noted that post-mortem decomposition could not rule out that this was not present at the time of the accident.
Findings
- The primary cause of the accident was the loss of tail rotor effectiveness (LTE), which induced a sharp rightward yaw.
- This yaw, combined with the high power demand of the hover, led the aircraft into a vortex ring state (VRS), causing a rapid loss of lift and a vertical descent.
- The pilot was hovering at a low altitude, which provided insufficient margin to execute an emergency recovery maneuver.
- The wind direction relative to the aircraft'ended up contributing to the reduction of tail rotor thrust.
- The pilot's limited flight experience hindered the ability to effectively manage the sudden emergency.