What happened
On December 9, 2010, a Robinson R22 helicopter, registration G-CBVL, crashed in a wooded area near Tourrettes-sur-Loup, France. The aircraft was performing a private ferry flight, traveling from a private platform near Cuneo, Italy, toward the United Kingdom. The flight included the pilot and one passenger.
During the flight, the aircraft was operating north of the Nice Côte d’Azur control zone. At approximately 07:40 UTC, the pilot established contact with the Nice Information service, reporting a position north of Escérène at 4,300 feet. However, by 07:51 UTC, air traffic controllers lost both radio and radar contact with the helicopter. A witness on the ground observed the aircraft diving toward the terrain, and the wreckage was later recovered on a steep, wooded hillside.
The investigation
The investigation focused on the mechanical integrity of the rotor system and the environmental conditions at the time of the accident. Investigators examined the wreckage at the CEPr laboratory, where they found the helicopter was completely destroyed.
Technical analysis of the wreckage revealed that the main rotor blade's low bearing had ruptured. Evidence showed that one of the main rotor blades had struck the cockpit and the left landing skid, causing the left door and part of the skid to be torn away. The investigation also noted that the engine was functional at the time of the accident and that the flight controls were intact. Meteorological data indicated that the region was experiencing strong winds and severe turbulence due to the Foehn effect, with wind speeds reaching up to 59 knots at 1,500 meters altitude.
Findings
- The primary cause of the accident was an inappropriate control input by the pilot while operating in turbulent conditions.
- This action triggered a mast bumping event, leading to the failure of the main rotor blade low bearing and a subsequent divergence of the main rotor's plane of rotation.
- The resulting contact between the rotor blade and the helicopter's structure led to the loss of lift and the subsequent crash.
- A contributing factor was the "destination objective" phenomenon, where the pilot likely felt pressured to complete the ferry flight despite deteriorating meteorological conditions.
- The pilot's lack of familiarity with the specific aerological characteristics of the region north of Nice also contributed to the accident.