Robinson Helicopter Company R22 N306RL accident near West Chester, Pennsylvania

Probable cause

The flight instructor's decision to continue the practice autorotation in known gusting wind conditions, which resulted in a hard landing and roll over.

NTSB analysis

The flight instructor was demonstrating straight-in autorotations to a power recovery over the runway. He stated that the wind during the flight was generally from the north, but shearing horizontally to the northeast/northwest. He began to flare the helicopter about 40 ft above the ground. About 20 ft above the ground, a large wind gust with a horizontal wind shear resulted in a drift to the right and loss of tail rotor effectiveness. He corrected the drift and heading with flight control inputs, returned to the runway area, and continued the flare. During the last portion of the flare, the helicopter encountered a vertical wind shear and climbed about 20 ft. At that point, "all wind stopped," and the helicopter descended. The instructor attempted a power recovery; however, the helicopter landed hard on the skids with some lateral motion. The helicopter bounced, the left skid broke, and the helicopter rolled and came to rest on its left side. The flight instructor did not report any preaccident mechanical malfunctions or failures with the helicopter that would have precluded normal operation. Postaccident examination of the wreckage confirmed substantial damage to the airframe and main rotor blades; there was no evidence of a preimpact mechanical failure or malfunction. Additionally, the flight instructor reported that there were no preaccident mechanical malfunction or failures that would have precluded normal operation.

Text from the NTSB. Open the NTSB docket for ERA17LA046 for the full record.