Incident Overview
A pilot conducting a pipeline patrol flight reported a loss of engine power during a routine maneuver, leading to an autorotation and subsequent landing. The pilot was marking pipeline valve positions using a GPS receiver at the time.
Flight Details
The pilot described the weather as clear but windy. Approximately one hour into the flight, the pilot initiated a turn to the west to overfly a location, then continued the turn back to the east on a downwind leg. After rolling out of the turn, the pilot began to increase power for a right turn to rejoin the pipeline route. At that moment, the helicopter yawed to the right and began losing engine power.
Autorotation and Landing
In response, the pilot immediately lowered the collective, added throttle, and turned left to the north. The helicopter was approximately 100 feet above ground level at an airspeed of about 60 miles per hour. The pilot stated that with the bank and autorotation, forward motion and ground speed were arrested. After flaring the helicopter and pulling pitch, the aircraft made a flat landing. The engine was shut down following the impact. The pilot reported that engine power did not return during the autorotation.
Post-Incident Examination
An examination of the helicopter's fuel system revealed the presence of water in both the left and right fuel tanks. No other anomalies or malfunctions were identified during the inspection.