NYC84LA070

The plt flew to greensburg, where he brought the helicopter to a 2 ft hover and departed with a max performance climb. He stated the helicopter began to exhibit control irregularities which he described as 'a dutch roll wobble type of shuffle.' He continued the flt & said the 'shuffle' subsided as pwr was reduced during apch to mt Pleasant. However, he experienced directional control problems during the apch which were proportional to changes in collective & throttle applications. Initially, he thought the problem was associated with the wind. The plt increased throttle, collective, rtpedal & began a climb. Then as a precaution, he cut the throttle to stop an increasing vibration & keep the eng from overrevving. Collective was reduced to maintain rotor RPM, then was increased on descent thru 20 ft AGL, but the acft landed hard, collapsing a skid. According to witnesses, it had insufficient pwr & made a 360 deg rotation before impact. Two main rotor blades separated and were found within proximity of the helicopter with impact damage.