Schweizer 269C-1 N61425 accident near Northumberland, Virginia

Probable cause

The pilot's inadequate remedial action after an inadvertent encounter with loss of tail rotor effectiveness.

NTSB analysis

The helicopter was full of fuel and hovering 100 feet above ground level when it encountered "a pretty good headwind" that registered 20 knots on the airspeed indicator. The helicopter shuddered, the nose yawed to the right, and the pilot's application of the left anti-torque pedal "had no effect" as the helicopter began to rotate around the main rotor mast. The pilot initially increased collective pitch to climb up and away from the trees. The pilot then applied forward cyclic, which lowered the nose of the helicopter and increased forward airspeed. This slowed the rate of rotation during the descent, but upon ground contact the landing skid "caught" and the helicopter rolled onto its side. Examination of global positioning system (GPS) track data extracted from the GPS unit on board the helicopter revealed an "S" shaped track that eventually oriented the helicopter into a quartering-tailwind condition above the crash site. The pilot was asked how long the helicopter was in the 100-foot hover before he "ran out of left pedal," and the left pedal input lost effectiveness. He replied, that "I didn't run out of pedal, I just didn't have any left or right." Examination of the wreckage revealed no preimpact mechanical deficiencies. According to Federal Aviation Administration Advisory Circular (AC) 90-95, "When maneuvering between hover and 30 knots: (1) Avoid tailwinds. If loss of translational lift occurs, it will result in an increased high power demand and an additional anti-torque requirement. (2) Avoid out of ground effect (OGE) hover and high power demand situations, such as low-speed downwind turns. (3) Be especially aware of wind direction and velocity when hovering in winds of about 8-12 knots (especially OGE). There are no strong indicators to the pilot of a reduction of translation lift... (6) Stay vigilant to power and wind conditions."

Text from the NTSB. Open the NTSB docket for NYC08LA254 for the full record.