Incident Overview
A helicopter conducting a flight test after fuel system maintenance experienced a rollover during an auto-rotation maneuver. The accident occurred while the pilot was performing a hovering auto-rotation to check rotor RPM. The helicopter had executed a normal takeoff and two right-hand traffic patterns to runway 18, including one go-around, before the test.
Pilot Account
According to the pilot, after flaring at 25 feet above ground and leveling at 5 feet with power off, both skids touched down with zero forward airspeed and the heading was maintained. He then noticed engine RPM rapidly increasing, so he rolled the throttle completely off and lowered the collective. The left skid began to lift off the ground, prompting the pilot to apply full left cyclic and full down collective. The helicopter teetered with the left skid approximately four to six inches above the ground before continuing to roll to the right. The pilot believed the maneuver had been performed successfully and suggested that either a strong wind gust or a mechanical defect caused the rollover. He noted that the helicopter was equipped with an articulated landing gear system and that if only one side's strut retracts, it creates a rolling moment.
Weather and Examination
Approximately 22 minutes before the accident, recorded winds at a location about seven nautical miles and 155 degrees from the accident site were from 200 degrees at 14 knots with gusts to 32 knots. An examination of the helicopter's controls and landing gear revealed no anomalies.