BRINKLEY, AR, USA
N107CW
Hughes MDL-369HS
The pilot was transporting a television crew to several high school football games. He had removed the left rear door of the aircraft to facilitate aerial photography of the games. The helicopter was in cruise flight at approximately 500 feet agl when the pilot heard a loud bang and the aircraft made a right yaw. The pilot said that movement of the directional control pedals was ineffective. He made a run-on landing, but the helicopter impacted two levees separating the right skid from the aircraft. The aircraft rotated to the right and came to a stop upright. Postcrash examination revealed that the tail rotor drive shaft had separated near its mid point. One of the tail rotor blades had seven small indentations (similar to a zipper) on one eighth inch centers near the tip of the blade. He reported that the 'three outboard marks on the top of the blade also exhibited span-wise streaks with a brass like appearance, which may be transferred metal.' Tests by the aircraft's manufacturer revealed the material transferred to the tail rotor blade leading edge was brass. None of the passengers remembered losing any personal items during the flight.
On September 12, 1997, approximately 1815 central daylight time, a Hughes MDL-369HS helicopter, N107CW, was substantially damaged during an emergency run-on landing following loss of directional control near Brinkley, Arkansas. The airline transport rated pilot and his 3 passengers were not injured. The helicopter was owned by Lance Aviation, Inc. and operated by Mid South Aviation, Inc., as a Title 14 CFR Part 135 air taxi flight. Visual meteorological conditions prevailed for the cross-country aerial photography flight which originated from Brinkley, Arkansas, approximately 15 minutes before the accident. A company VFR flight plan had been filed. The pilot reported to the Investigator-In-Charge (IIC) that he was transporting a television crew to several Friday high school football games. He had removed the left rear door of the aircraft to facilitate the aerial photography of the games. The pilot stated that the helicopter was in cruise flight approximately 500 feet agl when he heard a loud "bang." The pilot reported that "simultaneously, the aircraft experienced a right yaw of approximately 15 to 20 degrees and he noticed that movement of the directional control pedals were not effective in correcting the yaw." At approximately the same time, the pilot observed the tail rotor gearbox chip detector light illuminate and the airframe started to "noticeably vibrate." The pilot reported that he "began an immediate power-on decent to a recently harvested rice field." He performed a run-on landing with the aircraft, but had to "hop" over two 2 foot high levees hitting the right skid on both of them and subsequently separating the right skid from the aircraft. The pilot stated that the aircraft rotated to the right and came to a stop in an upright orientation tilting to the right. The pilot further stated that "during the main rotor coast down, the main rotor blades contacted the ground on the right side of the aircraft." The pilot reported to the IIC that "there were no indications of mechanical problems prior to the event." He further reported that "he believes that something hit the tail rotor." None of the passengers remembered losing any personal items during the flight. Postcrash examination by an FAA inspector revealed that the tail boom had separated near the midpoint and the tail rotor drive shaft had separated. He also found that one of the tail rotor blades had seven small indentations (similar to a zipper) on one eighth inch centers near the tip of the blade (three on the bottom of the leading edge and four on the top of the leading edge). He reported that the "three outboard marks on the top of the blade also exhibited span-wise streaks with a brass like appearance, which may be transferred metal." Testing by the aircraft's manufacturer, using a Scanning Electron Microscope, revealed the material transferred to the tail rotor blade leading edge was brass (see attached manufacturer's report).
The in flight collision of the tail rotor blade with an object that had a brass zipper on it, and the subsequent overload and failure of the tail rotor drive shaft. Factors were the object with the brass zipper on it and the unsuitable terrain for the forced landing.
Source: NTSB Aviation Accident Database
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