What happened
On May 18, 2012, a Robinson R22 Beta, registration PT-YLN, was conducting a flight instruction mission departing from Campo de Marte Aerodrome (SBMT) in São Paulo, Brazil. The flight involved an instructor and a student pilot.
Approximately fifty minutes into the flight, while operating in the traffic pattern, the instructor directed the student to perform an autorotation exercise. During the fifth attempt at this maneuver, the aircraft experienced a drop in main rotor RPM. The instructor took control of the aircraft and initiated procedures for a running landing. Upon touchdown, one of the main rotor blades struck the tail boom, causing it to separate completely from the fuselage. Despite the substantial damage to the aircraft, both occupants escaped the incident without injury.
The investigation
The investigation focused on the sequence of events during the autorotation maneuver and the subsequent impact. Investigators confirmed that the aircraft was airworthy, within weight and balance limits, and that all maintenance records were up to be date. The crew members held valid medical certificates and the instructor held a valid flight instructor rating.
Analysis of the flight dynamics revealed that the instructor failed to adequately assess certain operational parameters during the maneuver. The investigation established that the instructor did not recognize the developing risks in time to adopt a conservative approach, which might have prevented the student's errors from reaching a point of irreversibility.
Findings
- Inadequate application of flight controls during the landing phase.
- Errors in pilot judgment regarding the management of the autorotation maneuver.
- A failure to maintain a conservative instructional posture when student errors began to compromise flight stability.
Safety action
A recommendation was issued to the National Civil Aviation Agency (ANAC) to disseminate the lessons learned from this investigation to alert rotary-wing pilots and operators to the inherent risks associated with autorotation training.