What happened
During a scheduled annual recurrent training flight near St. John’s International Airport, a Eurocopter AS 350 BA (registration C-FHHH) was performing a simulated engine failure exercise. The training pilot intentionally reduced fuel flow to simulate a loss of power, initiating an autorotation at approximately 600 feet above ground level.
As the aircraft approached the end of the maneuver, the pilot attempted to restore engine power to execute an overshoot. However, the engine failed to spool up as expected. In an attempt to return to a suitable landing area, the crew executed a steep left turn. The helicopter's airspeed was significantly higher than the recommended 65 knots, which, combined with the steep turn, increased the rate of descent. The aircraft ultimately struck the ground in a nose-down attitude, resulting in two serious injuries and the destruction of the helicopter.
The investigation
Investigators examined the wreckage and the engine components at a specialized facility in Quebec. The examination of the Turbomeca Arriel 1B engine revealed no mechanical discrepancies, malfunctions, or evidence of thermal distress. The aircraft's instruments indicated the engine was running at the moment of impact.
Data from the GPS showed the aircraft was flying at approximately 100 knots at the start of the autorotation, later dropping to 90 knots during the attempt to recover power. The investigation also looked into the crew's safety equipment and flight procedures. It was noted that neither pilot was wearing a shoulder harness, and the training pilot was not wearing a helmet. The terrain, while free of obstacles, was a wet, spongy bog that was unsuitable for a controlled run-on landing.
Findings
- The training pilots had adopted a practice of manipulating the fuel flow control lever (FFCL) that was not aligned with the manufacturer's intent, due to a lack of explicit prohibitions in the rotorcraft flight manual.
- The engine did not respond as anticipated when the FFCL was advanced for the overshoot, leading to a high rate of descent.
- The autorotation was conducted at speeds exceeding the recommended limits, which, when paired with a steep turn, prevented the crew from arresting the descent.
- The severity of the pilots' back injuries was likely increased because neither was wearing a shoulder harness.
- The training pilot's facial injuries were likely exacerbated by the lack of a helmet.