What happened
On May 3, 2004, a Robinson R2 22 Beta (registration F-GJBE) was involved in an accident at the La Nouvelle helisurface in the Mafate cirque, La Possession, Reunion Island. The flight was a local private mission. After arriving from mainland France and performing a successful check flight the previous day, the pilot landed at the helisurface to refuel.
After replenishing both the main and auxiliary fuel tanks, the pilot attempted to depart for Pierrefonds aerodrome. The pilot established a hover at approximately two meters above the ground in ground effect before initiating forward translation for takeoff. During this phase, the main rotor RPM decreased, triggering the power limit warning light and an audible alarm. In response to the loss of power, the pilot attempted a right-hand turn to land back on the helisurface. During this maneuver, the aircraft could not be maintained in flight and descended into a patch of grass and small shrubs surrounding the landing area. During the touchdown, the tail rotor struck vegetation.
The investigation
Investigators examined the aircraft's performance capabilities relative to the environmental conditions at the time of the accident. The aircraft was operating at an altitude of 4,750 feet with temperatures between 10 and 15 °C. The takeoff mass was 570 kg, well within the maximum allowable mass of 622 kg. However, the investigators determined that at this altitude and temperature, the intake pressure was at or near the operational limit.
Analysis of the flight dynamics showed that as the pilot attempted to transition from a hover to forward flight, the natural slight sink of the helicopter required an increase in collective pitch. Because the engine was already operating at its performance limit, the requested increase in power could not be met, leading to the decay in rotor RPM.
Findings
- The primary cause of the accident was the insufficient consideration of the takeoff conditions regarding the aircraft's performance limits at high altitude.
- The pilot's attempt to execute a turning maneuver during the aborted takeoff required additional power that the engine could not provide under the existing atmospheric conditions.
- The tail rotor sustained damage due to contact with branches and vegetation during the uncontrolled descent.