SALINA, KS, USA
N9177F
Hughes 500C
The pilot reported losing directional control while maneuvering backwards and turning into the prevailing wind, which he reported as a "little gusty". Recorded weather reported a wind speed of 11 knots 12 nm east of the accident site. The pilot then performed a hovering autorotation during which the helicopter contacted the terrain with a left drift. The Rotorcraft Flying Handbook describes the characteristics associated with a loss of tail rotor effectiveness resulting from certain combinations of wind azimuth and helicopter airspeeds. Metallurgical examination of the helicopter's tail rotor assembly revealed no preexisting anomalies.
On April 24, 2000, at 1730 central daylight time, a Hughes 500C, N9177F, piloted by a commercial pilot, received substantial damage on impact with terrain 12 miles west of Salina, Kansas during a search for a buffalo. Visual meteorological conditions prevailed at the time of the accident. The 14 CFR Part 91 business flight was not operating on a flight plan. The pilot and passenger reported no injuries. The flight originated from the Salina Municipal Airport, Salina, Kansas, at 1630. The pilot reported, "...I flew a race track type pattern downwind at approximately 100 ft AGL and 70-80 knots. When turning back into the wind and backward...I noticed the nose veer left since it was a little gusty in the hills and first I didn't think much of it (I was at approx. 50 ft, 50-60 knots). I lowered the nose and increased power but the nose kept rotating to the left in ever tightening turns, using collective and cyclic I regained some altitude, we were running west toward higher terrain. Realizing I had some type of anti torque malfunction I began to try to neutralize the spin by increasing collective and slowly retarding throttle. I got the spin stopped at approximately 15 feet AGL over uneven and rocky terrain. Realizing I could not set down there I attempted to make controlled flight with cyclic, collective and throttle to a more suitable landing area. Each change of collective and throttle resulted in this aircraft turning left or right and ultimately resulted in this aircraft starting to spin to the right in ever tightening turns and as we were moving to flatter terrain at approx. 5 ft I attempted a hovering autorotation, which again stopped the spin but we started drifting left and touched down with some left drift resulting in the helicopter contacting the ground left skid 1st. The left skid apparently struck the ground 1st and as we were either sliding or spinning left of this point, the skid broke from the fuselage which continued left for approximately 15 ft. I assume the tail rotor or tail skid contacted the ground next, the main rotor contacted the tail boom and disintegrated, the tail boom came to rest on the right side of the aircraft..." The National Transportation Safety Board's Materials Laboratory examined the tail rotor assembly. The Material's Laboratory report stated that the inside of the blade root fitting contained the tubular portion of the hub trunion that was fractured. The fracture face displayed 45-degree shear lips consistent with tensile overload. The inside diameter of the blade root fitting exhibited mechanical damage. The pitch control arm revealed features typical of an overstress separation. Federal Aviation Administration publication, FAA-H-8083-21, Rotorcraft Flying Handbook, describes unanticipated yaw/loss of tail rotor effectiveness (LTE) as, "...LTE is not related to an equipment or maintenance malfunction and may occur in all single-rotor helicopters at airspeeds less than 30 knots. It is the result of the tail rotor not providing adequate thrust to maintain directional control, and is usually caused by either certain wind azimuths (directions) while hovering, or by an insufficient tail rotor thrust for a given power setting at higher altitudes..." The publication further states, "...Be especially aware of wind direction and velocity when hovering in winds of about 8-12 knots. There are no strong indicators that transnational lift has been reduced. A loss of translational lift results in an unexpected high power demand and an increased antitorque requirement..."
the loss of tail rotor effectiveness and the autorotation performed by the pilot. The unfavorable wind was a contributing factor.
Source: NTSB Aviation Accident Database
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