Aviation Accident Summaries

Aviation Accident Summary ANC12CA111

Anchorage, AK, USA

Aircraft #1

N4171J

ROBINSON HELICOPTER R22 BETA II

Analysis

The flight instructor was providing primary helicopter flight instruction to a student pilot. The instructor reported that while practicing a series of hovering autorotations, he inadvertently allowed the student pilot to drift to the left during the descent. The instructor then took control of the helicopter, applied right cyclic, and raised the collective slightly to level the helicopter and arrest the descent, but the helicopter started to descend with the right skid low. The instructor then added left cyclic and raised the collective further in an attempt to cushion the landing. The helicopter then drifted to the right as the right skid subsequently struck the ground. After touchdown, the helicopter’s skids slid over the asphalt surface before the right skid “caught,” the helicopter rolled to the right, and the main rotor blades struck the ground. The helicopter came to rest on its right side, sustaining substantial damage to the fuselage, tail boom, and main rotor drive system. The instructor reported that there were no preaccident mechanical problems with the helicopter that would have precluded normal operation. He also stated that the accident might have been avoided if he had taken corrective action sooner and with less input on the cyclic.

Factual Information

The certificated flight instructor (CFI) was providing primary helicopter flight instruction to a student pilot. The CFI reported that while practicing a series of hovering autorotations, he inadvertently allowed the student pilot to drift to the left during the descent. The CFI then took control of the helicopter, applied right cyclic and raised the collective slightly to level the helicopter and arrest the descent, but the helicopter started to descend with the right skid low. He then added left cyclic, and raised the collective further in an attempt to cushion the landing. The helicopter then drifted to the right as the right skid subsequently struck the ground. After touchdown, the helicopter’s skids slid over the asphalt surface before the right skid “caught” and the helicopter rolled to the right, and the main rotor blades struck the ground. The helicopter came to rest on its right side, sustaining substantial damage to the fuselage, tail boom and main rotor drive system. In his written statement to the NTSB, the pilot reported that there were no preaccident mechanical problems with the helicopter, and in the recommendations section of the NTSB 6120.1 form he reported that the accident might have been avoided if he had taken corrective action sooner, and with less input on the cyclic.

Probable Cause and Findings

The flight instructor's inadequate supervision of the student pilot during a hovering autorotation, which resulted in a dynamic rollover.

 

Source: NTSB Aviation Accident Database

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