LAX03CA279

The pilot lost directional control of the helicopter while maneuvering and the helicopter impacted water and sank. The pilot was manuevering over a boat race and was flying over the start line about 400 feet agl, on a magnetic heading between 235 to 240. He felt the helicopter drifting north and east. A turn was initiated; however, simultaneously, the helicopter "shuddered and snapped into a rapid right yaw." Left antitorque pedal was applied but the helicopter continued to turn 360 degrees repeatedly while losing altitude. Just prior to impact, the pilot pulled up on the collective and pushed the cyclic into a forward right position intending to assist the main rotor blades in stopping. The Rotorcraft Flying Handbook states that a loss of tail rotor effectiveness (LTE) is the occurrence of an uncommanded yaw rate that does not subside on its own accord, which can result in the loss of helicopter control. The recovery technique for LTE is full left pedal while simultaneously moving cyclic control forward to increase airspeed. If altitude permits, reduce power.

On September 6, 2003, about 1240 Pacific daylight time, a Bell 206B helicopter, N59506, lost control while maneuvering over a harbor near Long Beach, California. The helicopter, registered to and owned by a private individual, was being operated under the provisions of 14 CFR part 91. The private pilot and three passengers were not injured; the helicopter sustained substantial damage. The flight departed from Corona Airport, Corona, California, at 1135 for the local area personal flight. Visual meteorological conditions prevailed and no flight plan had been filed.

In a written statement, the pilot reported that the purpose of the flight was to view a boat race at Long Beach Harbor. He received a standard weather briefing via telephone, and then preflighted the helicopter, which included a passenger briefing. After arriving at the harbor, he maneuvered over the race course about 450 to 500 feet above ground level (agl). The helicopter's airspeed fluctuated between 25 and 40 miles per hour (mph). While over the start line of the race, the helicopter's heading was between 235 and 240 degrees magnetic. After completing the first flight over the race course, he flew back to the start line again about 400 to 450 feet agl. While over the start line, he felt the helicopter drifting to the north and east. A attempted turn to the south was made; however, the helicopter "shuddered and snapped into a rapid right yaw." Left antitorque pedal was applied but the helicopter continued to turn 360 degrees repeatedly while losing altitude. Just prior to impacting the water, the rotation ceased and the helicopter gained altitude momentarily. It then entered a rapid right yaw. When the pilot felt he was getting close to the water, he pulled up on the collective and pushed the cyclic into a forward right position intending to assist the main rotor blades in stopping. The pilot could not remember if he lowered the collective at the initial onset of the rotation.

The Rotorcraft Flying Handbook (FAA-H-8083-21) states that unanticipated yaw or loss of tail rotor effectiveness (LTE) is the occurrence of an uncommanded yaw rate that does not subside of its own accord and, which, if not corrected, can result in the loss of helicopter control. It further states, that LTE is not related to an equipment or maintenance malfunction and may occur in all single rotor helicopters at airspeeds less than 30 knots. The recovery technique for LTE is full left pedal while simultaneously moving cyclic control forward to increase airspeed. If altitude permits, reduce power.