On October 31, 2002, at 1700 eastern standard time, a Hughes 369A, N817SC, was substantially damaged when it impacted the Susquehanna River while practicing confined area maneuvers, and subsequently sank near Marietta, Pennsylvania. The certificated flight instructor, the certificated private pilot and the passenger were seriously injured. Visual meteorological conditions prevailed for the flight that departed Lancaster Airport (LNS), Lancaster, Pennsylvania, about1630. No flight plan was filed for the local instructional flight conducted under 14 CFR Part 91. Each of the three occupants was interviewed in the hospital on the evening of the accident by an officer with the Susquehanna Police Department. According to the police report, the flight instructor said he was at the controls of the helicopter when the accident occurred. He said that he misjudged the helicopter's height above the river, and one of the skids penetrated the water. In a written statement, the flight instructor wrote, "...misjudged the helicopter height above the river. One of the helicopter skids dipped into the water which caused the helicopter to pull nose down into the water." The pilot and the passenger provided similar accounts of the accident. A Federal Aviation Administration (FAA) inspector examined the helicopter after it was recovered from the water. According to the inspector, the tail boom was severed from the fuselage, but remained partially attached by the tail rotor drive shaft, cables, and electrical wiring. Both tail rotor blades were intact. The main rotor blades were fractured, and a 6-foot section of one blade was found on the river bank about 300 yards from where the helicopter sank in the river. A smaller section of main rotor blade was also found on the river bank about 100 yards away. No mechanical deficiencies were noted. The flight instructor held a commercial pilot certificate for rotorcraft-helicopter, and a certified flight instructor rating for rotorcraft-helicopter. He reported a total of 1,917 hours in helicopters, of which, 338 hours were in make and model. The flight instructor also reported that there were no mechanical deficiencies with the helicopter. Weather reported at Lancaster Airport, about 15 miles to the east, at 1653, included wind from 310 degrees at 6 knots, 10 statute miles visibility, and clear skies.