What happened
On December 20, 2004, a Robinson R44 II, registration EC-ITD, was conducting a private flight near Marbella, Spain. The flight began at La Axarquía Aerodrome, later stopping at an Estepona golf course to pick up two passengers for a sightseeing tour and transport to Mijas-Costa.
While flying near the summit of Cerro de Lastonar, the aircraft was operating at a low altitude and slow airspeed. The flight encountered strong, gusty winds and moderate to severe turbulence. During this phase, the helicopter began to rotate around its vertical axis, entering an erratic flight path. The aircraft struck a holm oak tree on the northern slope, which caused the loss of a tail rotor blade and a tail rotor guard. Following this impact, the helicopter fell vertically approximately 60 meters before striking the terrain and sliding down a steep slope.
The investigation
The CIAIAC investigation examined the flight conditions, the aircraft's performance, and the crew's qualifications. Investigators analyzed the meteorological conditions, noting that while visual flight rules (VFR) were applicable, the wind was highly gusty. The investigation also reviewed the aircraft's weight and power margins, noting that the helicopter was flying near its maximum takeoff weight at an altitude where it was operating out of ground effect (OGE). Additionally, the investigation looked into the pilot's credentials, finding that the pilot in command's license had expired and he lacked a specific type rating for the R44.
Findings
- The primary cause of the accident was the occurrence of Loss of Tail Rotor Effectiveness (LTE).
- The phenomenon occurred during slow flight in conditions characterized by strong, gusty winds and significant turbulence.
- The aircraft was operating at a high power demand due to its high weight and high altitude (out of ground effect).
- The pilot in command was operating with an expired flight license and lacked the required type rating for the Robinson R44 II.
- The presence of strong gusts and the abrupt topography contributed to the loss of control.