Lawrenceville, GA, USA
N5189K
MD HELICOPTER 369
During the approach to line up with a helipad, the commercial pilot noted that the helipad was not set up for landing into the wind, so he discontinued the approach and decided to land on a nearby wash rack, into the wind. As he turned right, the helicopter encountered a wind gust, or the wind was blocked by a nearby outbuilding, which can cause a turbulent effect. The helicopter suddenly and violently yawed right and pitched up. He attempted to correct the condition with pedal and cyclic inputs; however, a right spin ensued, and the helicopter spun to the ground and then came to rest on its right side. The pilot reported that there were no preimpact mechanical malfunctions or anomalies with the helicopter that would have precluded normal operation. It is likely that the pilot did not adequately compensate for wind conditions, and when he added power to compensate, the helicopter yawed right and pitched up. The pilot was unable to stop the yaw and lost helicopter control due to a loss of tail rotor effectiveness.
On September 1, 2017, at 1058 eastern daylight time, a MD Helicopters 369FF, N5189K, was substantially damaged while maneuvering to land at Gwinnett County Airport (LZU), Lawrenceville, Georgia. The commercial pilot and a pilot-rated crewmember were seriously injured. The helicopter was operated by the Gwinnett County Police Department as a local, public-use flight. Day, visual meteorological conditions prevailed at the time, and no flight plan was filed. The flight originated at LZU about 1000. The pilot reported the following that the preflight inspection of the helicopter and en route portions of the flight were uneventful. After about 1 hour on station performing law enforcement duties, the pilot returned to LZU to get ahead of deteriorating weather conditions. The flight was cleared to land on taxiway whiskey, then perform a side-step maneuver to the police helipad. The pilot recalled winds from 220° at 10 knots. He performed a normal approach to a 10-foot hover to taxiway whiskey. As he made a left turn to line up with the helipad, he noted that the cart on the helipad was not set up for a landing into the wind. He elected to discontinue the approach and make a right turn to land on a wash rack, into the wind. As the pilot was about to initiate the turn to the wash rack, the pilot noted a "strong wind gust" followed by a "sudden, uncommanded, violent, right yaw" and "what seemed to be an uncommanded climb." He applied cyclic and pedal inputs; however, the helicopter continued in a right spin for at least two full rotations until it impacted the ground. The pilot and crewmember were met by first responders and transported to a local hospital for treatment of their injuries. The pilot later reported that a small, county-owned outbuilding near the police pad can mask or block the wind, creating a turbulent effect. He stated that the perceived wind gust could also have been the tail rotor becoming "unmasked" from behind the outbuilding. The pilot further reported there were no preimpact mechanical malfunctions or anomalies that would have precluded normal operation of the helicopter. An inspector with the Federal Aviation Administration responded to the accident site and examined the wreckage. He reported that the helicopter came to rest on its right side in the grass, adjacent to a taxiway. There was no fire. Structural damage to the fuselage, tail rotor, and main rotor were confirmed. The main rotor blades were severed during the impact and were scattered up to 220 feet from the main wreckage. His examination of the wreckage did not reveal evidence of a mechanical malfunction or anomaly.
The pilot's inadequate compensation for wind conditions during the approach to landing, which resulted in a loss of helicopter control due to a loss of tail rotor effectiveness.
Source: NTSB Aviation Accident Database
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