Eurocopter AS 350 BA Accident During Recurrent Training

Accident Overview and Flight History On the day of the accident, a Eurocopter AS 350 BA helicopter, registration C-FHHH and serial number 1421, departed a company base located just south of St. John’s International Airport in Newfoundland and Labrador. The flight was intended for annual recurrent training, with two pilots on board. At 1428 Newfoundland and Labrador standard time, the helicopter took off and climbed to 1,200 feet above sea level on a south-westerly heading. At 1433, while approaching a bog at approximately 600 feet above ground level, the training pilot retarded the fuel flow control lever to simulate an engine failure, reducing engine power to 70 percent engine speed. The pilot receiving training commenced an autorotation, flying the helicopter into a wind estimated at 25 knots. A warning horn sounded intermittently throughout the exercise, indicating rotor speed was at or below 360 rpm, lower than the expected 405 rpm. As the helicopter descended through approximately 150 feet above ground level, the training pilot advanced the fuel flow control lever to the flight detent position to restore power for an overshoot. The engine, a Turbomeca Arriel 1B with serial number 4193, did not spool up as expected. The pilot continued the autorotation, but the helicopter overshot the bog and was above a wooded area facing a power line and a congested highway. A steep left turn was executed to return toward the bog, and collective pitch was increased to extend the glide. The helicopter struck the ground with a high vertical rate of descent in a nose-down, right-skid-low attitude. Both pilots sustained serious injuries, and the helicopter was destroyed. The emergency locator transmitter activated on impact, and fire rescue services arrived within fifteen minutes. The company helicopter transported the pilots to a hospital. ## Contributing Factors and Investigation Findings GPS data indicated that airspeed at the top of the autorotation was approximately 100 knots, decreasing to 90 knots when collective pitch was increased for the go-around. The recommended speed for autorotations on the AS 350 is 65 knots; higher speeds induce higher rates of descent. The low rotor speed was attributed to rotor speed flying controls being out of adjustment, the application of collective pitch before confirming engine power was restored, and the application of collective pitch to extend the range during the final phase of the autorotation. Although examination of the engine at Turbomeca facilities in Mirabel, Quebec, revealed no discrepancies, it could not be determined with certainty why the engine did not respond when the fuel flow control lever was advanced. Three plausible scenarios for the lack of power were identified: lack of crew coordination, a low setting of the fuel flow control lever, and an unidentified malfunction. The training pilot had 10,700 hours of total time with 750 hours on type, while the pilot receiving training had 10,270 hours with 475 hours on type. Both held valid commercial pilot licenses and type ratings. Neither pilot was wearing a shoulder harness, which likely contributed to the severity of their injuries. The training pilot was also not wearing a helmet and sustained severe facial and head injuries, whereas the other pilot, who was wearing a helmet, did not incur head injuries. The company operations manual did not explicitly state that pilots should wear shoulder harnesses, and it was common practice for company pilots to not use them for certain operations.