Eurocopter AS350BA N617LH accident near Globe, Arizona

Probable cause

The pilot receiving instruction’s failure to maintain adequate airspeed or control of the helicopter during a simulated hydraulic failure maneuver, which resulted in a hard landing. Contributing to the accident was the flight instructor’s delayed remedial actions and the lack of a positive exchange of control.

NTSB analysis

During a night vision goggle (NVG) training flight, the flight instructor initiated a simulated hydraulic failure on the downwind leg for landing. The flight instructor stated that during this maneuver, the pilot receiving instruction did not properly adjust the trim and did not maintain sufficient air speed. The helicopter slowed to about 20 knots, which was half the speed the flight instructor expected. When the flight instructor heard what he believed to be the low rotor horn and heard the pilot exclaim “uh-oh,” the flight instructor tried to regain control of the helicopter; however, the helicopter impacted the ground hard. Interviews with the pilot and instructor established that both were manipulating the controls after the initial loss of control and that no positive exchange of control had occurred. The pilot reported that the last time he had performed a simulated hydraulic failure was almost 1 year before the accident and that he had never performed such a procedure or had one demonstrated while operating with NVGs. The pilot and instructor reported no in-flight abnormalities with the helicopter before the initiation of the simulated hydraulic failure, and postaccident examination of the hydraulic system components revealed no abnormalities that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for WPR10LA046 for the full record.