What happened
On February 3, 2013, a Eurocopter AS350 BA, registered C-GPHN, departed from a base near Sept-Îles Airport, Quebec, for a training session. The crew consisted of a flight instructor and two pilots in training. The flight initially involved practicing landings in unprepared areas before moving to the Sept-Îles Airport to perform engine failure and hydraulic failure drills.
During the hydraulic failure simulation, the aircraft was operated without hydraulic pressure assistance. While performing a low-altitude pattern on Runway 31, the aircraft experienced a sudden, sharp movement of the cyclic stick toward the forward and left positions. The flight instructor attempted to recover the aircraft, but the helicopter entered a steep left bank and a nose-down attitude. The main rotor blades struck the runway, causing the aircraft to land heavily on its left side. The impact caused heavy damage to the helicopter, though no fire occurred. The flight instructor sustained serious injuries, while the two trainee pilots suffered minor injuries.
The investigation
The investigation examined the aircraft's hydraulic components and found no mechanical malfunctions or evidence of in-flight system failure. However, investigators noted that the flight instructor's maneuvers deviated from the recommended procedures. Specifically, the instructor conducted multiple patterns and takeoffs without hydraulic pressure assistance, contrary to the warnings in the Rotorcraft Flight Manual (RFM).
Investigators also looked into the cockpit configuration. The center console featured a toggle switch for hydraulic testing that lacked a protection mechanism, making it susceptible to accidental activation. Furthermore, the investigation found that the flight instructor's training methods did not adhere to the specific procedures outlined in the RFM Supplement 7, and the instructor's previous experience with older, lighter-load rotor systems may have led to an underestimation of the control forces present in this model.
Findings
- The flight instructor failed to follow approved procedures by conducting several flight patterns and takeoffs without hydraulic pressure assistance.
- The aircraft's flight profile deviated from the manufacturer's recommendations for depressurized hydraulic systems.
- The sudden change in aerodynamic feedback forces caused the cyclic stick to move unexpectedly, leading to a loss of control.
- The flight instructor was unable to restore hydraulic pressure because the left collective stick lacked a hydraulic cut-off button.
- The aircraft's low altitude at the time of the roll prevented the instructor from recovering before the rotor blades struck the ground.