Robinson Helicopter Company R22 N90764 accident near Prescott, Arizona

Probable cause

The pilot's failure to maintain adequate main rotor rpm while maneuvering at a low altitude.

NTSB analysis

The pilot was circling over a residential structure to allow his passenger to take photographs. He descended to 50 feet above ground level and slowed to about 40 to 50 knots indicated airspeed. The pilot said that near the completion of the second circle, he "felt and heard something," then observed the engine rpm and rotor rpm decaying along with the activation of the low rotor rpm horn and warning light. The pilot stated that "it may have been that what I felt and heard was a reaction to the downwind heading." The pilot lowered the collective and added power; however, due to his low operating altitude, the corrections did not have time to take effect before the helicopter impacted the terrain. The pilot reported the wind from 210 degrees at 10 knots gusting to 15 knots. The closest airport reported wind from 180 degrees at 7 knots, variable from 150 to 210 degrees. Robinson Safety Notice SN-34, "PHOTO FLIGHTS – VERY HIGH RISK," states, in part: "While maneuvering, the pilot may lose track of airspeed and wind conditions. The helicopter can rapidly lose translational lift and begin to settle." A postaccident engine run was conducted and the engine ran normally with no mechanical problems.

Text from the NTSB. Open the NTSB docket for WPR09LA160 for the full record.