Aviation Accident Summaries

Aviation Accident Summary ATL00LA034

DALLAS, NC, USA

Aircraft #1

N303BT

Hughes 369D

Analysis

The pilot was performing an out-of-ground effect (OGE) hover at 500 agl while performing aerial photography for a live news broadcast. While hovering OGE on a heading of 195 degrees with the winds were from 030 degrees at 10 knots, the helicopter experienced several unanticipated right yaw excursions. The pilot made the decision to perform an autorotation landing. He stretched the landing to clear power lines and upon impact with the ground, the helicopter rolled onto its right side. According to the pilot, he previously experienced a tail rotor failure in the same model helicopter, and believed the helicopter was possibly experiencing a similar malfunction. Advisory Circular 90-95 (Unanticipated Right Yaw in Helicopters) instructs the pilot to avoid tailwinds while maneuvering between hover and 30 knots and to be aware of wind direction and velocity when hovering in winds of 8-10 knots, especially OGE. A recommended recovery technique is to adjust the controls for normal forward flight. A postaccident examination of the helicopter revealed no engine or airframe abnormalities.

Factual Information

On March 6, 2000, at 1219 eastern standard time, a Hughes 369D, N303BT, registered to and operated by Jefferson Pilot Broadcasting, was substantially damaged when it collided with terrain during an autorotation landing near Dallas, North Carolina. The airline transport pilot and one passenger were not injured. Visual meteorological conditions prevailed for the business flight being conducted under Title 14 CFR Part 91, and no flight plan was filed. The flight originated from Charlotte, North Carolina, at 1145. According to the pilot, he was hovering out-of-ground effect (OGE) at 500 feet above ground level while performing an aerial photography mission for a live news broadcast. During the hover, a Department of Forestry fire-fighting helicopter arrived on the scene and requested that N303BT move off to the side so that it could drop water. The pilot repositioned the helicopter approximately 2 miles east of the fire area to continue filming live coverage. The pilot hovered the helicopter on an approximate heading of 195 degrees, and the winds were from 030 degrees at 10 knots. After hovering OGE for approximately 3 to 4 minutes, the helicopter experienced an unanticipated yaw to the right approximately 30-45 degrees. The pilot applied full left pedal with no effect. He then lowered the collective and regained directional control. Moments later, the helicopter again yawed 10 to 20 degrees to the right, and the pilot made the decision to perform an autorotation landing. In attempt to clear power lines, he "stretched" the approach, and the helicopter touched down in a plowed field. Upon impact with the ground, the main rotor blades flexed downward, severing the tail boom. The helicopter bounced, became airborne, and impacted the ground a second time, landing on the right skid. The helicopter then rolled over onto its right side. A postaccident examination of the helicopter was conducted on March 8, 2000, at the facilities of Atlanta Air Salvage in Griffin, Georgia, with the assistance of engineering representatives from Rolls-Royce Allison and Boeing. Unobstructed turbine rotation of the engine was established through the gearing to the power output shaft. A vacuum check of the fuel system was performed, and no discrepancies were observed. Fuel was present in the fuel lines to the fuel nozzle. All cyclic, collective main rotor, N2 governor, and N1 control linkage exhibited continuity throughout full range of movement, and the anti-torque flight control linkage exhibited continuity up to where the control tube was severed at the tailboom. No engine or airframe anomalies, which would have effected aircraft performance, were found. The pilot was interviewed by an FAA inspector following the accident. He stated that he had previously experienced a tail rotor failure in the same model helicopter, which was due to bearing failure in the tail rotor drive system. He was also familiar with loss of tail rotor effectiveness, and had experienced this flight condition in the past. He stated that he believed that at the time of the accident, the helicopter might again be experiencing one of these conditions. The passenger, a news cameraman, was filming the flight from inside the cockpit when the accident occurred. According to evidence provided by the recorded film, at no time during the right yawing excursions or the attempted autorotation landing did the helicopter lose directional control. According to FAA Advisory Circular 90-95 (Unanticipated Right Yaw in Helicopters), the pilot is instructed to "avoid tailwinds" while maneuvering between hover and 30 knots. The pilot should "be especially aware of wind direction and velocity when hovering in winds of about 8-10 knots (especially OGE)." A recommended recovery technique should sudden unanticipated right yaw be experienced is for the pilot to "adjust controls for normal forward flight."

Probable Cause and Findings

The pilot's improper use of flight controls during an emergency landing. Factors were an encounter with a loss of tail rotor effectiveness (LTE) during an out-of-ground effect hover, the pilot's inadequate weather evaluation, and his failure to follow proper procedures for LTE.

 

Source: NTSB Aviation Accident Database

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