What happened
On September 24, 2004, an AS-350 B2 helicopter, registration PP-EDS, was participating in a joint operation involving the Federal Police, Military Police, and Fire Department of Pernambuco. While performing a mission near Orocó, the crew attempted to board passengers while the aircraft was in a hover due to the irregular terrain preventing a landing.
During the boarding of the third passenger, the aircraft's tail rotor collided with a rock. The impact caused intense vibrations throughout the airframe. The pilot attempted an emergency landing near the banks of the São Francisco River, but the severe vibrations hindered control. During the landing attempt, the aircraft touched down with a forward movement and a nose-down attitude, causing the main rotor blades to strike the ground. The impact severed the tail boom and resulted in the aircraft overturning. While the two pilots and two passengers escaped without injury, a systems operator and one passenger sustained minor injuries. The aircraft was a total loss.
The investigation
CENIPA's investigation focused on the sequence of events leading to the tail rotor strike and the subsequent loss of control. Investigators examined the operational procedures of the CITAER unit, the training levels of the crew, and the physical configuration of the cockpit. The investigation revealed that the maneuver of boarding passengers during a hover was not covered in the aircraft's manual and had not been specifically trained for by the crew.
Furthermore, investigators looked into the cockpit ergonomics, noting that the pilot's seat harnesses were exposed to the passengers, allowing for accidental interference. The investigation also evaluated the organizational structure of the operating unit, specifically regarding flight safety supervision and the adequacy of mission briefings.