LINVILLE, NC, USA
N9333F
HUGHES 269B
THE HELICOPTER TOOK OFF FROM A PRIVATE GOLF COURSE IN MOUNTAINOUS TERRAIN. THE ELEVATION WAS AT THE UPPER LIMIT OF THE HELICOPTER'S CAPABILITY TO HOVER IN GROUND EFFECT. AFTER DEPARTURE, A CLIMBING TURN WAS MADE TO THE NORTHEAST. ABOUT 300 FEET AT 40-45 MPH, THE TAIL PITCHED UP, ROTOR RPM DECAYED, AND THE HELICOPTER BEGAN LOSING ALTITUDE. THE PILOT REPORTED THAT THE HELICOPTER ROTATED CLOCKWISE ABOUT ITS VERTICAL AXIS. THE WIND WAS FROM THE WEST ABOUT THREE TO SIX KNOTS. AN AUTOROTATION WAS INITIATED. AFTER TURNING 180 DEGREES, TO THE WEST, TREES WERE OVERFLOWN WHICH THE TAIL ROTOR CONTACTED. AFTER TURNING BACK INTO THE WIND, DIRECTIONAL CONTROL WAS REGAINED AND THE HELICOPTER TOUCHED DOWN, HARD, ON THE GOLF COURSE. MANUFACTURER'S PERSONNEL STATED THAT THE CIRCUMSTANCES WERE CONSISTENT WITH PREVIOUS ACCIDENTS THAT INVOLVED A LOSS OF TAIL ROTOR EFFECTIVENESS (LTE). AN OWNER'S MANUAL FOR THE ACFT WAS CONSULTED. NO INFORMATION WAS PROVIDED REGARDING THE CONDITIONS CONDUCIVE TO LTE.
On October 5, 1993, at about 0955 eastern daylight time a Hughes 269B helicopter, N9333F, landed hard, following a loss of control, during the intial climb after takeoff from the Linville Golf Course, Linville, North Carolina. The helicopter was registered to Hylton Helicopters. It was rented by the commercial pilot and operated by him under 14 CFR Part 91, and visual flight rules. Visual meteorological conditions prevailed. A flight plan was not filed for the personal flight. There were no injuries to the pilot nor his passenger. The flight was originating at the time of the accident. The pilot reported that he departed from the golf fairway and climbed above the trees. About 75 feet above the trees, 200-300 feet above the ground, at about 45 knots forward speed the wind shifted to a tailwind. Main rotor speed began to decrease and the fuselage yawed right. Full throttle was applied and the collective "milked" in an attempt to restore main rotor speed. The helicopter rotated 360 degrees about the vertical axis at least once as the pilot attempted to fly over a tree line to execute an autorotation to the fairway. The tail rotor clipped a tree limb and the helicopter landed hard bending the aft crossover tube. The density altitude, at the time of the accident, was calculated as approximately 5500 feet Mean Sea Level. The FAA Approved Rotorcraft Flight Manual for the Huges 269B contained a chart that depicts the Hover Ceiling vs Temperature, Skid Height 3 Feet (attached). The chart depicts the maximum hover ceiling, at helicopter maximum weight of 1670 pounds, as 4700 feet. The elevation of the accident site, as listed by the pilot on the 6120.1/2, Pilot/Operator's Aircraft Accident Report, was 4700 feet. The weight of the helicopter was not determined. The elevation of the golf course is shown on an Atlanta Sectional Aeronautical Chart as between 4500 and 5000 feet. A second chart in the Flight Manual, the Height Velocity Diagram (attached), depicts that at an airspeed of 46-51 mph the helicopter is at the edge of the operational avoidance area. During a telephone conversation, the helicopter manufacturer's representative stated that the circumstances described by the pilot, coupled with the ambient conditions, were consistent with other accidents that involved a loss of tail rotor effectiveness. The flight manual used for the calculations in the preceding paragraph did not contain any information regarding the conditions under which a loss of tail rotor effectiveness may occur.
THE PILOT'S FAILURE TO MAINTAIN AIRSPEED THAT WOULD HAVE AVOIDED A LOSS OF TAIL ROTOR EFFECTIVENESS (LTE), AND HIS IMPROPER COMPENSATION FOR TAILWIND CONDITION. A FACTOR WAS THE LACK OF INFORMATION IN THE PILOT'S OPERATING HANDBOOK REGARDING THE CONDITIONS UNDER WHICH LTE MAY OCCUR.
Source: NTSB Aviation Accident Database
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