On January 4, 2002, at 1505 eastern standard time, a Hughes OH-6A helicopter, N46TP, registered to, owned, and operated by the City of Tampa Police Department, collided with terrain during training maneuvers in a field near Tampa International Airport in Tampa, Florida. The public use instructional flight was conducted under the provisions of Title 14 CFR Part 91 with no flight plan filed. Visual meteorological conditions prevailed at the time of the accident. The certificated flight instructor and the commercial pilot received minor injuries, and the helicopter sustained substantial damage. The flight departed the Tampa Police Aviation hangar in Tampa, Florida, at 1400. The flight instructor was acting as check airman for the commercial pilot's annual airman competency/proficiency check. The commercial pilot completed several maneuvers before a full-touchdown autorotation was initiated in a dry, unmowed, grassy practice area west of the approach end of runway 27 at Tampa International Airport. The maneuver, from entry at 500 feet above ground level to touchdown, was actively monitored by the flight instructor and was performed correctly with the rotor RPM, airspeed, attitude, and sink rate within parameters. The pilot initiated a flare at 100 feet above ground level, and, through final descent to the ground, lifted the collective to cushion the landing. The helicopter touched down in a slight nose-down attitude and began a slow ground run for three to five feet. The flight instructor and commercial pilot then reported a very hard "hop" that threw both upward against their shoulder harnesses, and the commercial pilot's helmet struck the upper doorjamb. The commercial pilot stated, "the helicopter then rose up left side low, then slammed into the ground, with the right side taking the brunt of the force." The helicopter then began gyrating violently, and both the flight instructor and commercial pilot shut it down. Examination of the helicopter revealed the main rotor blade severed the tail boom, separating the tail rotor and vertical/horizontal assembly from the airframe. One main rotor blade was separated, and the other main rotor blade displayed deformation. The pilots reported no mechanical failures.