What happened
On August 21, 2009, an instructional flight involving a Robinson R-22, registration PT-YFV, was conducting maneuvers at Jacarepaguá Aerodrome (SBJR) in Rio de Janeiro. The flight, operated by Nacional Escola de Pilotagem, included an instructor and a student pilot performing autorotation exercises.
During the second autorotation attempt, the air traffic control tower notified the crew that operations might soon be suspended due to deteriorating weather conditions. The instructor decided to proceed with one final autorotation to land. During the flare phase of this maneuver, the aircraft encountered a sudden wind gust of 21 knots. This gust caused the helicopter to experience a sudden rightward yaw, a left rolling motion, and a significant loss of altitude. The resulting movement caused the main rotor to strike the tail boom, severing the tail cone. Despite the severe damage, the instructor maintained control and successfully landed the aircraft. Both the instructor and the student were uninjured.
The investigation
CENIPA's investigation focused on the meteorological conditions, the flight maneuvers, and the mechanical state of the aircraft. Investigators examined the wind data from the aerodrome's automated station, which confirmed that while the wind was generally within limits, a rapid shift in direction and intensity occurred just prior to the accident.
Technical experts from the Flight Test Special Group (GEEV) also inspected the aircraft's flight controls. They specifically examined a knot found on the longitudinal elastic trim cord. The analysis concluded that this knot did not restrict control movement and did not contribute to the accident. The investigation also looked into the student's previous flight records, noting documented difficulties with autorotation exercises.
Findings
- Abrupt control inputs: The pilot's sudden application of flight controls in an attempt to correct the loss of control and the heavy sink rate near the ground contributed to exceeding the main rotor blade's clearance limits.
- Adverse weather: A 21-knot wind gust placed the helicopter in a state where recovery was impossible.
- Pilot judgment: The instructor chose to attempt another training maneuver despite being notified of deteriorating weather conditions.
- Instructional oversight: The instructor did not sufficiently account for the student's documented difficulties with autorotation maneuvers, especially given the forecast for high winds.
- Air Traffic Services (ATS) communication: The lack of real-time updates from the tower regarding significant wind shifts reduced the crew's situational awareness.
- Training requirements: The investigation noted that the adoption of specialized training requirements, similar to the US SFAR 73-1, might have prevented the occurrence.