Cranston, RI, USA
N90013
Bell 206B
The pilot was performing a series of passes for a ground camera, at an altitude of about 350 feet AGL, and an indicated airspeed of 20 to 25 knots. Three passes were completed into the wind with no problems. On the fourth pass, the pilot noticed the wind had changed from a headwind to a 90 degree left crosswind of about 10 to 15 knots. At the same time, the nose of the helicopter drifted right and he was unable to regain control prior to ground impact. A check of the FAA Advisory Circular on Unanticipated Right Yaw revealed the wind change placed the helicopter in situation where he was susceptible to loss of tail rotor effectiveness (LTE).
On November 26, 2003, about 1600 eastern standard time, a Bell 206B, N90013, operated by Horsham Valley Airways, Horsham, Pennsylvania, was substantially damaged after the pilot experienced a loss of control in-flight, and performed an uncontrolled descent to the ground in Cranston, Rhode Island. The certificated airline transport pilot and camera operator received minor injuries. Visual meteorological conditions prevailed for the corporate flight which departed from Theodore F. Green Airport (PVD), Providence, Rhode Island, about 1545. No flight plan had been filed for the local flight that was conducted under 14 CFR Part 91. According to the pilot, the helicopter was under contract to television station WJAR, Providence, Rhode Island. The purpose of the flight was to perform low level fly-bys, while being photographed from the ground. The pilot reported that he talked with the ground cameraman, and discussed flight paths to be flown and camera positions on the ground, based upon the wind direction. The fly-bys were to be conducted at an altitude of about 350 feet above ground level, at an indicated airspeed of 20 to 25 knots. The pilot reported that he was using a flag on a pole as a wind check for the passes. The first three passes were conducted without incident, and the wind was aligned with the ground track. The inbound heading on each pass was about 230 degrees magnetic. The pilot said that on his fourth pass, the helicopter was stabilized, with the torque about 65 to 70 percent, and the left pedal depressed about 50 percent forward of the neutral position. He looked down at the flag, and saw that it was extended straight out to the right, with an estimated velocity of 10 to 15 knots. At the same time, with no advanced warning, he felt the nose of the helicopter drift right. He initially corrected with left pedal; however, the nose continued to drift right. He followed the nose right turn with cyclic control, and lowered the collective. While descending, he momentarily raised the collective; however, that increased the rate of rotation. He lowered the collective again which increased the rate of descent. One more time, he raised the collective to arrest the descent. The rate of turn increased, and he again lowered the collective, which increased the rate of descent. He performed a forced landing in a parking lot between parked semi-trailers, and a building. According to an inspector from the Federal Aviation Administration (FAA), the helicopter's rear cross tube was spread, and had driven up into the fuselage, which ruptured the fuel cell. The vertical fin, 90 degree gear box, and tail rotor were separated from the tail boom. The engine mounts were also fractured. In addition, the main rotor was separated from the mast, and laying nearby. Multiple, horizontal slash marks were found on the end of a trailer that was adjacent to the accident site. In addition, a computed weight and balance revealed the helicopter weighed about 3,000 lbs at the time of the accident. The 1451, 1551, and 1651 weather observations at Providence recorded the wind direction and velocity as 200 degrees at 8 knots; 210 degrees at 7 knots; and 220 degrees at 7 knots, respectively. According to FAA Advisory Circular 90-95 - UNANTICIPATED RIGHT YAW IN HELICOPTERS: "...LTE is a critical, low-speed aerodynamic flight characteristic which can result in an uncommanded rapid yaw rate which does not subside of its own accord and, if not corrected, can result in the loss of aircraft control...LTE is not related to a maintenance malfunction and may occur in varying degrees in all single main rotor helicopters at airspeeds less than 30 knots...Any maneuver which requires the pilot to operate in a high-power, low-airspeed environment with a left crosswind or tailwind creates an environment where unanticipated right yaw may occur...Avoiding LTE may best be accomplished by pilots being knowledgeable and avoiding conditions which are conducive to LTE. Appropriate and timely response is essential and critical...." A check of the FAA Advisory Circular on Unanticipated Right Yaw revealed the wind change placed the helicopter in situation where he was susceptible to loss of tail rotor effectiveness (LTE).
The pilot's inadvertent encounter with loss of tail rotor effectiveness. A factor was the wind change.
Source: NTSB Aviation Accident Database
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