What happened
On April 9, 2003, a Robinson R44 helicopter, registration C-GRDI, was conducting a local familiarization flight near Peace River, Alberta. The flight, operated by Trek Enterprises, included the pilot-in-command and the company's incoming chief pilot designate. While the flight was not officially designated as training, the crew performed several practice autorotations with power-on recoveries.
During these maneuvers, the engine RPM exceeded prescribed limits on at least two occasions. During the fourth autorotation, the pilot-in-command was flying the aircraft when the airspeed and rotor RPM dropped significantly. As the helicopter entered a right-hand turn toward the practice field, the rotor RPM reached a critical low, causing the controls to move erratically. The helicopter subsequently lost flight capability and struck a wooded area. The impact caused substantial damage to the aircraft, though no fire occurred. Both pilots sustained severe injuries to their lower extremities.
The investigation
The investigation examined the qualifications of the crew, the flight's objectives, and the mechanical performance of the aircraft. It was established that the pilot-in-command had not flown the Robinson R44 since the previous flying season and had recently been training on a Bell 206, which features a high-inertia rotor system. This differs significantly from the low-inertia system of the Robinson R44, where rotor RPM can decay rapidly.
Investigators also looked into the role of the passenger, the chief pilot designate, who was not type-rated for the Robinson R44. While the pilot-in-command was aware of the engine overspeed and the resulting inspection requirements, he chose to proceed with the exercises despite initial misgivings. Furthermore, the investigation noted that no pre-flight briefing was conducted to establish command authority or review emergency procedures for the maneuvers.
Findings
- The primary cause of the accident was that the aircraft's airspeed and rotor RPM decreased to a level where the helicopter became uncontrollable.
- The pilot-in-command failed to recognize the onset of a critical flight condition and did not implement corrective actions in time.
- The passenger, while highly experienced in other aircraft, was not qualified on the Robinson R44 and did not intervene when the aircraft became unstable.
- The pilot's recent training on a high-inertia rotor system (BH06) was not directly transferable to the low-inertia characteristics of the Robinson R44.
- Both crew members operated under the assumption that the other possessed sufficient proficiency to maintain safety during the maneuvers.