Hamilton, MT, USA
N504WD
AIRBUS AS-350
The flight instructor, in the left seat reported that he was providing flight instruction to the commercial pilot, in the right seat, which included a series of hovering autorotations. According to the instructor, as the commercial pilot hovered the helicopter about 3 or 4 ft above the ground, the instructor initiated the hovering autorotation by reducing the floor-mounted throttle (fuel flow control lever) to about 70% N1, and the helicopter descended to about 1 ft above the ground. As the commercial pilot tried to cushion the touchdown, he inadvertently applied too much collective pitch, and the helicopter ballooned to a higher altitude. During the second descent, the main rotor rpm continued to decay, and the helicopter’s skids struck the ground. The instructor did not take control of the helicopter during this sequence. A postflight inspection revealed substantial damage to the tailboom.
On May 4, 2015, about 1045 mountain daylight time, an Airbus AS-350 BA helicopter, N504WD, sustained substantial damage as a result of a hard landing during a practice hovering autorotation at the Ravalli County Airport in Hamilton, Montana. The helicopter was being operated as a visual flight rules local area proficiency/instructional flight under Title 14 Code of Federal Regulations Part 91 when the accident occurred. The helicopter was registered to Hat Creek Helicopters LLC, Hamilton, Montana. The flight instructor and commercial pilot were not injured. Visual meteorological conditions prevailed at the time of the accident and no flight plan was filed. The flight originated from the Ravalli County Airport. In the flight instructor’s written statement, dated June 1, 2015, he reported that the purpose of the flight was to provide flight instruction to the commercial pilot, which included hovering autorotations. The flight instructor related that before starting the first hovering autorotation maneuver, he had the pilot hover the helicopter about 3 or 4 ft above the ground. The flight instructor then initiated the hovering autorotation by reducing the floor-mounted throttle (fuel flow control lever) to about 70% N1, and the helicopter descended to about 1 ft above the ground. He said that as the pilot tried to cushion the touchdown, he inadvertently applied too much collective pitch, and the helicopter ballooned to a higher altitude. The main rotor rpm decayed as the helicopter descended, and the skids subsequently struck the ground hard. The flight instructor characterized the landing as “firm” but both pilots were unaware of any damage sustained to the helicopter. The flight instructor reported that they performed several additional training maneuvers and then landed without further incident. A postflight inspection revealed substantial damage to the tailboom. The flight instructor reported that it was difficult to control the throttle due to its location, mounted on the pedestal between the front seats, necessitating the release of either the cyclic or collective control to manipulate the throttle. Further, not having an idle detent made the pilot/instructor vulnerable to inadvertently shutting down the engine while trying to manipulate the throttle for training or emergency purposes. The flight instructor verified that there were no preimpact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.
The pilot's excessive collective application during an autorotation. Contributing to the accident was the flight instructor's inadequate supervision of the training flight.
Source: NTSB Aviation Accident Database
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