What happened
On November 1, 2007, a Bell 206B helicopter, registration PT-HTJ, was performing a training flight from the ABC-Helicópteros helipad in Ribeirão Preto, Brazil. The aircraft was carrying two pilots and two passengers. During the takeoff phase, the helicopter experienced a sudden loss of control, characterized by several right-hand yawing motions. The aircraft subsequently struck the ground in a median strip between two highways, approximately 100 meters from the takeoff point. The impact was followed by a fire that completely destroyed the airframe. All four occupants sustained minor injuries and successfully evacuated the wreckage.
The investigation
CENIPA's investigation focused on the aerodynamic conditions and the qualifications of the crew. Investigators examined the engine, which was analyzed by technicians from Rolls-Royce; no engine failure was identified as a contributing factor. Meteorological data revealed a high temperature of 35°C and a tailwind of approximately 13 knots at the time of the accident.
The investigation also scrutinized the crew's credentials. It was established that the pilot in the right seat, who was performing the takeoff, lacked the specific type rating for the Bell 206B. Furthermore, the pilot in the left seat was not qualified as a flight instructor and had been flying with an expired type rating since 2006. The investigation also noted that while the aircraft was within its maximum takeoff weight limits, the combination of high temperature, altitude, and tailwind created a high-risk environment for the loss of tail rotor effectiveness.
Findings
- The primary cause of the accident was the loss of tail rotor effectiveness, which triggered an uncommanded rightward yaw.
- The pilots lacked the necessary experience and type-specific training to identify the phenomenon and apply the required immediate corrective inputs, such as full left pedal application.
- The crew was operating the aircraft without the required legal qualifications or valid type ratings.
- Inadequate flight planning regarding the impact of wind direction, temperature, and density altitude on tail rotor performance.
- Poor cockpit coordination and task management due to the lack of qualified personnel in the cockpit.
- The pilot in the left seat was not authorized to provide instruction on this specific aircraft type.