Bell 206 N134VG accident near Rome, New York

Probable cause

The pilot's improper termination of a practice autorotation with power recovery, which resulted in low rotor rpm, an unstable landing, and a rollover. Contributing to the accident was the evaluator's inadequate oversight.

NTSB analysis

The accident occurred during a Part 135 competency check ride for the pilot. On board were two Federal Aviation Administration (FAA) aviation safety inspectors, one seated in the left seat performing the check ride and another in the left rear seat providing oversight and on-the-job training to the other inspector.

After performing maneuvers, the flight returned to the airport where the pilot was to perform a straight-in autorotation with power recovery. As the recovery began, the pilot recalled that he advanced the throttle to the full open position, which the FAA inspector confirmed by attempting to rotate the throttle to the open position, and noted the power turbine and rotor RPM needles were in the green arc. As the pilot raised the collective for recovery, the low rotor warning light and low rotor warning horn both activated. The helicopter impacted the runway hard, rotated right and rolled over on its left side with the engine still operating. The engine continued to run until the inspector in the left seat was able to reach and rotate the right throttle grip “several times” until the engine stopped. The helicopter’s fuselage was substantially damaged. Examination of the helicopter after the accident did not reveal any preaccident malfunctions or failures that would have precluded normal operation.

According to the inspector in the left seat, as the pilot began the recovery and rotated the throttle, the inspector checked the throttle position, attempting to rotate the (left side) throttle grip towards the open position, and it did not move. In retrospect, the inspector considered, when he attempted to rotate the throttle grip and it did not move, that it may not have been in the fully open position and the resistance he felt in the (left) grip may have been a result of the pilot holding his (right) throttle grip tightly. The pilot had been holding the controls somewhat tightly during the flight.

If the throttle were not in the fully open position during the recovery from the autorotation, the governor would not automatically maintain the rotor RPM. As the pilot raised to collective to flare, this could result in a reduction of rotor RPM and apparent partial loss of power.

Text from the NTSB. Open the NTSB docket for ERA21LA275 for the full record.