On May 11, 1998, at 2030 eastern daylight time, N8045H, a Hughes 269-A, was substantially damaged when it landed hard during a practice autorotation at the Maxon Field, Alexandria Bay, New York. Visual meteorological conditions prevailed and a flight plan was not filed. The certificated flight instructor and commercial pilot were not injured. The local instructional flight was conducted under 14 CFR Part 91. According to the commercial pilot, the purpose of the flight was to practice touchdown autorotations toward attaining his instructor certificate. He said that during the autorotation, the helicopter touched down hard on the left main landing gear. The left skid then separated and the helicopter rolled over to the left. The pilot said there was no discussion how the autorotation should be done. He said, "...entered auto at 60 mph, 1,000 feet. [I] allowed the airspeed to drop to 55 without maintaining rotor rpm. Flare was entered at 50 ft...helicopter fell through possibly to excessive flare resulting in too much of a vertical drop." The pilot said there was no mechanical malfunction with the helicopter, and the accident could have been prevented if the instructor had taken the controls. He said the instructor was a relatively new instructor. He also stated that the flight instructor might have been hesitant to correct a more experienced pilot. The pilot reported over 3,420 hours of rotorcraft flight experience, including 63 hours in make and model. The flight instructor reported over 440 hours of rotorcraft flight experience, including 41 hours in make and model. Several attempts were made to contact the instructor including mailing the pilot/operator report. The report was returned to the NTSB with a note that he was no longer at the address on file with the FAA. There was no forwarding address available.