On June 17, 2005, approximately 1530 Pacific daylight time, an MBB BO-105 helicopter, N314MS, landed hard during a simulated autorotation in an area north of Logan International Airport, Billings, Montana. The certified flight instructor, who was flying at the time, as well as his pilot-rated passenger, were not injured, but the aircraft, which is owned and operated by Metro Aviation, Inc., sustained substantial damage. The 14 CFR part 91 proficiency flight, which departed Logan International about 60 minutes prior to the accident, was being operated in visual meteorological conditions. No flight plan had been filed. According to the instructor pilot, he had just finished giving the other pilot a proficiency check, and had then taken control of the aircraft so that he could perform some maneuvers for his own proficiency. He performed one simulated engine-out autorotation to a touchdown, and was completing his second when the accident occurred. He said that he initiated the autorotation from about 1,000 feet above the ground (agl), and began establishing a flare attitude at an altitude of 100 feet agl. At that time he noticed that the descent rate of the helicopter was excessive, but instead of adding power along with the increase in collective, he decided to continue the simulation of the power loss. Just prior to touchdown, the pilot established a landing attitude and used all of the available collective to cushion the landing. When the helicopter touched down, the descent rate was still greater than the pilot desired, and immediately after contacting the ground, the main rotor flexed downward and contacted the top of the tail boom. According to the pilot, there were no problems with the aircraft's flight controls or engine. He further stated that he felt that the variable wind had changed directions during his descent from 1,000 feet agl, and that he was therefore inadvertently landing downwind. In addition, he felt that the high density altitude (approximately 5,700 feet) left little room for error. In his discussion with the NTSB, the pilot stated that under the conditions, he should have initiated a go-around when he sensed the excessive descent rate at 100 feet agl.