ERA17LA046

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.

On November 15, 2016, about 1500 eastern standard time, a Robinson R22, N306RL, was substantially damaged during a practice autorotation landing at Brandywine Airport (OQN), West Chester, Pennsylvania. The flight instructor and a student pilot were not injured. The helicopter was privately owned and operated under the provisions of 14 Code of Federal Regulations Part 91 as an instructional flight. Day, visual meteorological conditions prevailed at the time, and no flight plan was filed. The local flight departed OQN about 1430.The flight instructor reported that he was demonstrating straight-in autorotation landings to a power recovery using the runway. The wind was generally from the north, but shearing from the northeast to the northwest, horizontally. During an autorotation to runway 9/27, he began to flare about 40 feet above the ground. At 20 feet, a large gust with a horizontal wind shear caused the helicopter to drift to the right and lose tail rotor effectiveness. He corrected the drift and heading with flight control inputs, returned to the runway, and continued the flare. During the last portion of the flare, a vertical wind shear was encountered, and the helicopter climbed, uncommanded, about 20 feet. At that point, "all wind stopped," and the helicopter descended. He attempted a power recovery; however, the helicopter landed hard on the skids, with some sideward motion. The helicopter bounced, the left skid broke, and the aircraft rolled and came to rest on its left side. The two pilots egressed the helicopter and were met by first responders. An inspector with the Federal Aviation Administration responded to the accident site and examined the wreckage. Structural damage to the airframe was confirmed The main rotor blades were deformed from impact forces and the tail boom was partially separated. He determined that the helicopter was operated within the aircraft's weight and balance limitations at the time of the accident; however, it was operated at the forward center of gravity limit. The pilots weighed about 200 pounds each, which placed the helicopter near the upper weight limit. His examination of the wreckage did not reveal evidence of a mechanical failure or malfunction. He reported that the surface wind at the time of the accident varied between 330 and 350 degrees at 11 to 14 knots. The flight instructor did not report any preaccident mechanical malfunction or failures with the helicopter that would have precluded normal operation.