FAIRBANKS, AK, USA
N8367F
Robinson R-22
The helicopter pilot turned downwind at 30 feet above the ground. The winds were between 15 knots and 30 knots. The main rotor rpm decayed, and the pilot was unable to regain rpm by lowering the collective, disengaging the engine speed governor, and increasing the throttle. During the ensuing forced landing, the helicopter bounced and rolled onto its side. The pilot stated that he did not have tail rotor authority at the low rotor rpm when the helicopter bounced. The engine was operated on a test stand, and exceeded the minimum power requirements for a serviceable engine. No anomalies were noted with the engine, governor, or governor controller.
On April 1, 1999, about 1030 Alaska standard time, a Robinson R-22 helicopter, N8367F, sustained substantial damage during a forced landing about 38 miles south of Fairbanks, Alaska. The commercial pilot and sole passenger were not injured. The helicopter was operated by Chena River Aviation under 14 CFR Part 135, conducting wolf captures for the State of Alaska, Department of Fish and Game. The flight departed the Chena Marina Airport in Fairbanks at 0930. Visual meteorological conditions prevailed at the time of the accident, and a company VFR flight plan was filed. The pilot told the NTSB investigator-in-charge (IIC) during a telephone interview on April 1, that he turned downwind in 15 knots to 30 knots of wind, at 30 feet above the ground to capture a wolf. He noticed the rotor and engine rpm decaying. He attempted to lower the collective, disengage the engine speed governor, and increase the throttle, but the rotor speed continued to decay. The pilot said the low rotor speed warning horn activated during his descent, and he made a forced landing to a clearing. The helicopter bounced, and rolled onto its side. He stated that he did not have tail rotor authority at the low rotor rpm when the helicopter bounced. The pilot estimated seven to ten gallons of fuel remained in the fuel tanks at the time of the accident. The engine was examined and operated on a test stand at the Robinson Helicopter facility on May 3, 1999. The testing was observed by an NTSB investigator. No anomalies were noted with the governor motor, the governor controller, or the engine. The power level produced throughout the test exceeded the minimum specified by the manufacturer.
The failure of the pilot to maintain rotor rpm during a downwind turn. A factor in the accident was the inadequate altitude to recover from the loss of rotor rpm.
Source: NTSB Aviation Accident Database
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