On December 8, 2014, at 1115 mountain standard time, an Enstrom Helicopter, N409LH; experienced a total loss of engine power during cruise flight. The student pilot performed an autorotation to a field. The helicopter sustained substantial damage. The student pilot was uninjured. The helicopter was operated by Mountain One Helicopters under 14 Code of Federal Regulations Part 91 as an instructional flight that was operating on a flight plan. The flight last departed from Greeley-Weld County Airport, Greeley, Colorado, and was destined to Platte Valley Airpark, Hudson, Colorado. During a solo cross country flight flown by a student pilot, the helicopter experienced a total loss of engine power during cruise flight. The pilot performed an autorotation to a field. During landing flare, the helicopter tail struck the ground resulting in the main rotor blades flexing downwards, which severed the tail rotor boom. The helicopter sustained substantial damage to the fuselage and rotor blades. The pilot was uninjured. The engine was test run by the operator without the knowledge and permission of the National Transportation Safety Board Investigator-In-Charge or the Federal Aviation Administration Inspector assigned to the accident investigation. The operator stated the engine was run without any anomalies.