Incident Overview
A helicopter conducting a stage check for a Commercial Pilot certificate experienced a hard landing following a simulated emergency. The flight was under the supervision of a Certified Flight Instructor (CFI) in preparation for the commercial practical test. The scenario involved illumination of the low fuel light, prompting the pilot to select a landing spot and land promptly.
Sequence of Events
The pilot identified a flat area and noted obstructions, including high power lines. At approximately 300 feet above ground level (agl), the pilot began to slow the helicopter and checked the gauges. The airspeed was about 50 knots, with a rate of descent between 400 and 500 feet per minute (fpm). The pilot applied carburetor heat and noted that manifold pressure was below 18 inches of mercury.
About 30 to 45 seconds later, the low rotor revolutions per minute (rpm) warning light illuminated, accompanied by the corresponding warning horn. The pilot observed a very high vertical descent and entered an autorotation by applying down collective and aft cyclic. The low rotor rpm warning light and horn extinguished.
The CFI recalled that the helicopter was about 200 feet agl and 40 to 43 knots on final during the maneuver. The CFI heard a reduction in noise, followed by the low rotor rpm horn and light. He then lowered the collective and rolled on the throttle. When there were no immediate effects, he lowered the collective fully and applied aft cyclic aggressively. The rotor rpm was between 94 and 97 percent. The aft cyclic allowed the rotor rpm to increase, but little to no forward speed was achieved.
As the ground approached rapidly, the CFI pulled up on the collective. The helicopter fell straight down, impacted the ground hard, and rolled to the left. The helicopter sustained substantial damage. The instructor sustained serious injuries. The engine remained operating, so the pilot turned off the ignition. The pilot reported no mechanical irregularities prior to beginning the maneuver.