Background
The purpose of the air medical flight was to pick up a patient who had been involved in a motor vehicle accident in a rural area and transport him to a hospital. The helicopter landed to the north on the front lawn of a private residence.
Departure and Loss of Control
After the patient was boarded, the commercial pilot attempted to determine the wind direction but found no visual cues. He estimated the winds were about 10-15 knots from between 330 and 030 degrees. He had encountered similar winds while en route to the landing zone. A second EMS pilot who arrived at the scene after the accident reported winds from 030 to 050 degrees at 10 knots.
The pilot brought the helicopter to a hover and maneuvered to the right to avoid power lines crossing the residential property. When departing, he began a vertical ascent but was trying not to increase the collective above the available torque. He was concerned about clearing the power lines and losing tail rotor effectiveness.
When the helicopter reached an altitude abeam of the power lines, it began an uninitiated spin to the right. The pilot reported that torque was near 100 percent. He applied full left torque pedal and attempted to gain forward airspeed, also using the cyclic to follow the nose of the aircraft in an attempt to fly out of the turn. The pilot was unable to gain airspeed, and the helicopter continued to spin to the right and descend.
Autorotation and Landing
The pilot initiated an autorotation by lowering the collective and placing the throttle in the idle position, which stopped the spinning. When the helicopter was about 10 to 20 feet above ground, the pilot placed the collective in the full-up position to cushion the landing. However, there was not sufficient main rotor rpm to stop the high rate of descent, and the helicopter landed hard in a field adjacent to the private residence.
Findings
Examination of the helicopter revealed no preimpact structural, system, or other mechanical anomalies. The Bell 206-L1 flight manual indicates a critical wind azimuth with an increased risk of loss of tail rotor effectiveness when winds are encountered between 050 and 210 degrees.