Accident Details
A helicopter experienced an accident while practicing autorotative landings with power recovery. The certified flight instructor (CFI) reported that the student had completed 11 previous such maneuvers on the same flight, with the accident occurring on the 12th. The student initiated the autorotation from approximately 500 feet above ground level (agl) at an indicated airspeed between 65 and 75 knots, maintaining 65 knots during descent. At about 75 feet agl, the student flared the helicopter. The descent continued, and at approximately 20 feet agl with an indicated airspeed of about 20 knots, the student added power. The helicopter then yawed to the left. The CFI took control and, at roughly 10 feet agl and an indicated airspeed between 10 and 20 knots, pulled collective. The helicopter impacted the grass with the right skid low, pivoted 90 degrees to the right, and rolled onto its right side.
Pilot Accounts
The student pilot provided a slightly different account. He reported that after departing for another practice autorotation, he flew the downwind leg abeam runway 36, applied carburetor heat, checked for annunciation lights, and noted the intended touchdown area. He announced his intentions on the common traffic advisory frequency (CTAF), turned base and final, slowed to approximately 70 knots, confirmed the CFI was ready, counted to three, and entered the maneuver at about 500 feet. He applied right anti-torque pedal input and aft cyclic control, maintaining 65 to 70 knots during descent while keeping main rotor rpm at approximately 100%. He flared at 50 to 60 feet agl, slowed to a walking speed, continued descending, leveled the helicopter, and applied throttle to recover to a hover. He then looked back into the cockpit and observed the CFI grabbing the controls. The helicopter subsequently contacted the grass and rolled onto its right side. The student stated he did not hear the low rotor warning horn, could not recall if the helicopter yawed when he applied power, and was surprised to see the CFI take control.
Postaccident Investigation
After the accident, the engine was operated on a test stand with a test club installed. No discrepancies were noted.