What happened
On April 22, 2013, a Robinson R22 Beta, registration PT-YST, was conducting a proficiency check for a commercial helicopter pilot license. The flight departed from Aeródromo Campo de Marte in São Paulo. Following the completion of the evaluation, the examiner requested a move to a plateau near the Anhanguera Highway in Cajamar, SP, to demonstrate a maneuver.
While performing a 360-degree autorotation, the examiner assumed control of the aircraft. During the execution of the turn, the aircraft encountered a tailwind component, causing the airspeed to drop below recommended levels and the rotor RPM to decrease. The low RPM warning horn sounded, indicating the rotor speed had fallen below 97%. In an attempt to recover, the pilot applied forward cyclic and increased power, but the aircraft continued to descend rapidly, eventually striking the ground with substantial damage. Both occupants survived the impact without injury.
The investigation
CENIPA's investigation focused on the technical execution of the maneuver and the regulatory environment. Investigators found that the Robinson Flight Training Guide does not include a 3-60 degree autorotation with power recovery, only recommending 180-degree maneuvers. Furthermore, the investigation highlighted a discrepancy in Brazilian regulatory instructions (IS 00-02); a previous revision had explicitly required that manufacturer operating manuals take precedence over instructional maneuvers, but this restriction was removed in a later revision, potentially leading examiners to perform unauthorized maneuvers.
The investigation also examined the organizational culture of the flight school, noting a lack of standardized manuals and a failure to provide evidence of instructor training programs. The investigation found no mechanical failures in the engine, rotor, or flight controls.
Findings
- The pilot attempted a 360-degree autorotation, a maneuver not prescribed by the manufacturer's training guide.
- The aircraft experienced a drop in rotor RPM below the safe operating threshold.
- The examiner's decision-making and flight judgment contributed to the loss of control.
- Inadequate organizational oversight and a lack of standardized training procedures within the operator's management system.
- Regulatory ambiguity regarding the precedence of manufacturer manuals over instructional guidelines.