What happened
On February 10, 2022, a Schweizer 269C-1 helicopter, registered as PR-CEU, was conducting a flight training mission at Capão da Canoa Airfield (SSKK) in Rio Grande do Sul, Brazil. The flight was part of a practical instructor training course operated by the Military Brigade of the State of Rio Grande do Sul. The crew consisted of two pilots: an instructor and a student.
During the mission, the crew was practicing various emergency maneuvers, including engine failure simulations during hovering, taxiing, and takeoff. During the third takeoff-related exercise, the student pilot initiated a climb, reaching approximately 50 feet of altitude at an indicated airspeed of 45 knots, at which point an engine failure was simulated to practice autorotation.
As the aircraft performed a running landing, it experienced an abrupt rolling motion. The right skid broke upon impact with the ground, and the main rotor blades struck the terrain. Despite the substantial damage to the aircraft, both pilots emerged uninjured.
The investigation
CENIPA investigators examined the flight parameters against the manufacturer's performance data. The investigation focused on the aircraft's flight profile relative to the Height-Velocity (H-V) diagram provided in the Pilot's Flight Manual. The analysis revealed that the flight profile—specifically the combination of 50 feet of altitude and 45 knots of airspeed—placed the helicopter within the "shaded area" of the diagram, a zone where the manufacturer does not guarantee a safe landing following an engine failure.
The investigation also reviewed the operator's training program, noting that the curriculum being used was outdated and did not comply with the updated requirements established by ANAC Resolution No. 512. Furthermore, investigators analyzed the mechanics of the crash, determining that the aircraft's descent rate and landing technique led to a dynamic rollover. This occurred when the skids became misaligned with the flight path, creating a pivot point that caused the aircraft to roll beyond the critical angle of control.
Findings
- The flight profile was initiated within the unsafe shaded area of the Height-Velocity diagram, increasing the complexity of the maneuver.
- Improper application of flight controls during the running landing contributed to the loss of control.
- The pilot's attitude and execution of the maneuver contributed to the occurrence of a dynamic rollover.
- The operator's training program was non-compliant with current regulatory requirements.