What happened
On September 24, 2012, a Robinson R22 Beta helicopter, registration PR-JRG, was conducting a local flight instruction mission for a Commercial Pilot (Helicopter) certificate. The flight originated from Campo de Marte (SBMT) with an instructor and a student on board. The flight was being conducted in favorable visual meteorological conditions.
During the execution of an autorotation training maneuver, the instructor observed that the aircraft's airspeed had dropped below 60 knots. To recover the aircraft, the instructor took control and applied rapid inputs to the collective, cyclic, and power lever to accelerate the helicopter and initiate a climb. However, the instructor reported that the engine did not respond promptly to these rapid commands. Due to the low altitude, the pilot attempted an emergency landing.
The aircraft struck the ground with high energy in the Parque Ecológico do Tietê, near Guarulhos, SP. The impact caused the helicopter to roll along its longitudinal axis and tip to the left. The collision resulted in substantial damage to the aircraft, including damage to the main transmission, rotor blade fractures, and damage to the tail boom, stabilizers, and tail rotor.
The investigation
CENIPA's investigation focused on the sequence of events during the autorotation maneuver and the effectiveness of the recovery attempt. The investigation confirmed that both pilots were qualified and possessed sufficient experience for the intended flight. While the aircraft held a valid Certificate of Airworthiness, investigators noted that the engine and airframe logbooks were not up to date.
The analysis examined the aerodynamic requirements of the R22 autorotation maneuver, noting that maintaining airspeed between 60 and 70 knots is ideal for the transition to the flare. The investigation also reviewed manufacturer safety guidelines, specifically Robinson Helicopter Company's Safety Notice SN-38, which emphasizes the importance of maintaining airspeed, RPM, and a safe decision height during such maneuvers.
Findings
- Improper application of flight controls during the recovery attempt.
- Pilot judgment regarding the timing and execution of the maneuver.
- Instructional techniques related to the management of the autorotation sequence.