On January 31, 2003, at 1230 central standard time, a Bell 206L-1 helicopter, N27AE, piloted by a commercial pilot, sustained substantial damage when the main rotor severed the tailboom during an intentional autorotation at the West Plains Municipal Airport (UNO), West Plains, Missouri. Visual meteorological conditions prevailed at the time of the accident. The instructional flight was conducted under the provisions of 14 CFR Part 91 on a company flight plan. The check airman and dual student reported no injuries. The flight departed UNO at 1215 for the local area flight. The helicopter operator was Air Evac EMS Inc., an on-demand air ambulance service. According to a written statement provided by the company check airman, he was demonstrating an autorotation maneuver to the dual student when the accident occurred. The check airman stated: "Entered the autorotation, slowed to 60 [knots], rotor was in the green, gas producer stable and aircraft in trim." The check airman reported that at approximately 20 feet agl he "determined the sink rate was excessive" and he decided to perform a "power recovery." The check airman reported that his grip on the throttle did not allow an adjustment of the throttle. The check airman reported, "I repositioned my hand, started opening the throttle while leveling the aircraft and applying a cushioning pitch pull." The helicopter impacted off the left side of the runway with "the skids aligned with the direction of travel slightly aft skid low." The check airman stated, "The aircraft rocked up onto the toes of the skids and I increased collective pitch and applied aft cyclic, when I did the main rotor impacted the tailboom severing it."