What happened
On May 27, 2020, an EC-120B helicopter, registration PR-FPM, operated by the Federal Highway Police Department, was performing a transfer flight between a helipad at the Federal Highway Police Superintendence Headquarters and the Jacarepaguá Aerodrome (SBJR) in Rio de Janeiro.
As the aircraft was approaching the M2 position of the apron, the pilot in command (the second in command was operating the controls) initiated a 90-degree right turn to align the aircraft with the required heading. During this maneuver, the helicopter entered an uncontrolled turn to the right. The aircraft subsequently touched the ground abruptly, dragging its skids across the apron surface for approximately 365 degrees of rotation. The incident resulted in minor damage to the aircraft's skids, but all four crewmembers remained unharmed.
The investigation
CENIPA's investigation focused on the aerodynamic conditions and pilot inputs during the maneuver. Investigators analyzed meteorological data, which showed that while general weather conditions were favorable for VFR flight, there were significant variations in wind speed and direction at the aerodrome. Specifically, at the time of the incident, the wind was recorded at an azimuth that placed the aircraft in a region of directional instability.
Technical inspections of the EC-120B revealed no mechanical malfunctions or system failures that contributed to the event. The investigation also reviewed the aircraft's weight and balance, finding it was within manufacturer limits. The analysis centered on the interaction between the wind direction and the pilot's pedal inputs during the turn.
Findings
- The aircraft was operating in a region of directional instability caused by the wind azimuth.
- The pilot did not sufficiently reduce or reverse the right pedal input after initiating the turn, which allowed the yaw to accelerate.
- There was a likely reduction in the pilot's situational awareness and responsiveness during the unexpected yaw.
- Inadequate assessment of aerodynamic parameters during the maneuver contributed to the loss of control.