What happened
On May 9, 2013, a Robinson R22 Beta helicopter, registration PT-HPK, departed from Campo de Marte Aerodrome in São Paulo for a local flight instruction session. The crew consisted of a flight instructor and a student pilot. During the training session, the aircraft moved to the Parque Ecológico do Tietê in Guarulhos to perform low-altitude maneuvers.
While performing a lateral displacement maneuver, the right skid of the helicopter made contact with the uneven ground, which was covered in tall grass and medium-sized shrubs. This contact triggered a dynamic rollover. The aircraft tilted to the right, rolled along its longitudinal axis, and overturned. During the impact, the main rotor blades struck the ground, and the tail boom was severed. The student pilot remained uninjured, while the instructor sustained minor injuries. The aircraft sustained substantial damage.
The investigation
CENIPA investigators examined the flight history, crew qualifications, and environmental conditions. The investigation confirmed that the instructor was properly rated and the student was undergoing training for a private pilot license. Both crew members held valid medical certificates. The aircraft was airworthy, within weight and balance limits, and had sufficient fuel for the mission.
Investigators analyzed the mechanics of the rollover, identifying that the aircraft exceeded the critical roll angle, where pilot control authority is lost. The investigation also noted that the instructor had taken control of the aircraft shortly before the loss of control occurred, but the intervention was too late to prevent the roll. Furthermore, a failure in the standardized procedure for transferring controls between the instructor and student was identified. The investigation also noted that the terrain at the training site was unsuitable due to surface irregularities and vegetation.
Findings
- The primary cause of the accident was a dynamic rollover initiated by the right skid contacting uneven terrain and tall grass.
- Inadequate pilot judgment and flight instruction regarding low-altitude maneuvers contributed to the event.
- Poor cockpit coordination and a failure to follow standard procedures during the transfer of controls between the instructor and student.
- The presence of obstacles and irregular ground surfaces at the training site increased the risk of skids contacting the terrain.
Safety action
Following the investigation, a safety recommendation was issued to the National Civil Aviation Agency (ANAC) to disseminate the lessons learned from this accident to flight training centers. Consequently, updated guidelines were integrated into supplementary instructions to ensure instructors teach preventive actions against dynamic rollover during theoretical training, as this phenomenon cannot be safely simulated in practical flight training.