NTSB Factual Report

On July 25, 2001, about 1840 eastern daylight time, a Bell 206B-III helicopter, N313JP, registered to, and operated by the Jacksonville Sheriff's Office, as a Title 14 CFR Part 91 public-use flight, crashed in a residential area in Jacksonville, Florida. Visual meteorological conditions prevailed, and no flight plan was filed. The pilot and copilot received minor injuries, and the helicopter was destroyed. The flight had originated from Craig Municipal Airport, Jacksonville, Florida, the same day, about 1705.

The pilot stated that he departed from Craig Airport on a routine law enforcement patrol, and responded to a call to look for a submerged car in a small lake. The pilot further stated that he started a descent into the area heading east into the wind, and down to 300 feet. He said he made several passes, and on the last pass he made a left turn, and had started turning to the right when the aircraft developed a fast yaw to the right, indicative of imminent loss of tail rotor effectiveness (LTE). The pilot said he immediately reduced collective and nosed the aircraft forward, and started losing altitude fast with no significant improvement in the yaw rate to the right. He said he pulled power to arrest the descent rate, and the yaw rate got faster, and he made a forced landing between two houses, pulling power at the bottom to arrest the descent rate. During the forced landing, the right skid touched down on the side of the roof, the aircraft then rolled left and came down to the ground. The pilot said that prior to the accident, there had been no mechanical failure or malfunction to the aircraft, or to any of its systems.

FAA Advisory Circular 90-95 describes Unanticipated Right Yaw in Helicopters, or loss of tail rotor effectiveness (LTE) as a critical, low-speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate, which does not subside of its own accord, and if not corrected can result in a loss of aircraft control. AC 90-95 further describes LTE as a condition which is not related to a maintenance malfunction, but one which may occur in varying degrees in all single main rotor helicopters at airspeeds less than 30 knots. For further detail on LTE please refer to FAA Advisory Circular 90-95.

NTSB Probable Cause

the pilot's failure to recognize and correct for unanticipated right yaw/loss of tail rotor effectiveness (LTE) during an approach to hover at a low altitude, which resulted in a loss of control and the helicopter descending and colliding with a house and the ground.