Engine Failure
The pilot reported that the engine failed while the helicopter was on final approach at an altitude of 25–30 feet above ground level. The failure occurred unexpectedly, prompting the pilot to initiate an autorotation.
Autorotation and Landing
The pilot executed an autorotation to the asphalt surface of the helicopter parking ramp. Steel plates had been placed on the parking spots to prevent ramp erosion. During the landing, the left front skid tube collided with one of these steel plates, causing the front cross tube to fracture.
Subsequent Impact and Damage
As a result of the fractured cross tube, the nose of the helicopter pitched downward. The main rotor disc then flexed and struck the tail boom, severing it aft of the horizontal stabilizer.
Engine Examination
Post-accident examination of the engine revealed that the No. 1 turbine wheel had failed. The failure was determined to be the result of previous cycles of high temperature, specifically 2300 degrees Fahrenheit.