N701SH

On August 6, 1994, at 1257 hours Pacific daylight time, a Robinson R-22B helicopter, N701SH, collided with level terrain following a loss of control during a landing approach near Agua Dulce, California. The pilot was completing a visual flight rules personal flight. The helicopter, operated by Group 3 Aviation, Van Nuys, California, was destroyed by impact forces; there was no fire. The certificated commercial pilot and passenger received minor injuries. The flight originated at Van Nuys Airport, Van Nuys, California, at 1230 hours.

The accident location was an open field behind a house. The pilot intended to land in the field to visit occupants of the house. Los Angeles County Sheriff's Department deputies assigned to the aero bureau responded to the scene.

The deputies interview two witnesses who were awaiting the helicopter's arrival. The witnesses told the deputies that they observed the helicopter approaching from the west (traveling east). One witness stated that, as it was approaching, the helicopter's descent appeared to stop momentarily and then increase. The witnesses stated that the helicopter dropped to the ground from 10 feet and rolled over.

The pilot told the deputies that everything was normal until the last 100 feet. The pilot said he felt like he was settling with power. At 10 feet, he did not have power available and collided with the ground.

The pilot reported in a written statement that the winds were out of the west at 2 knots and the temperature was 90 degrees. He stated that he was caught in a downdraft while on final approach. The pilot also said that the helicopter did not experience any preimpact mechanical failures or malfunctions.

The deputies reported that the prevailing temperature was 100 degrees, the surface winds were from the west between 15 and 20 knots, and the crash site elevation was 3,200 feet mean sea level (msl). The deputies also reported that the density altitude was estimated at 6,100 feet msl.

According to the Robinson Operator's Handbook, Performance Specifications section, the helicopter can hover out of ground effect at 105 degrees and 3,200 feet msl at its maximum gross weight.

The Federal Aviation Administration (FAA) Basic Helicopter Handbook states the following: "In recovering from a settling-with-power condition, the tendency on the part of the pilot to first try to stop the descent by increasing collective pitch will result in increasing the stalled area of the rotor and increasing the rate of descent. Recovery can be accomplished by increasing forward speed, and/or partially lowering collective pitch."

The manufacturer's representative defined settling-with-power as a vortex ring state. The recovery from a vortex ring state would require a minimum of 100 feet.