On Thursday, March 17, 1994, at 0100 eastern standard time, a Piper PA-28R-200, N4465T, a personal flight, lost partial engine power and collided with a house during approach to runway 27 at the Washington County Regional Airport, Hagerstown, Maryland. The pilot received minor injuries and the airplane was substantially damaged. Visual meteorological conditions prevailed. The departure point was Louisville, Kentucky. The flight was conducted under 14 CFR Part 91. The pilot reported the flight from Louisville to Hagerstown was uneventful. He stated that there was some "...moderate turbulence in the clouds, and light to moderate turbulence coming over the mountains to the west of [Hagerstown] as I was descending." The pilot wrote, "I entered downwind leg of the traffic pattern for runway 27, I put my gear down, then I put the prop lever and mixture lever full forward and I noticed my RPM's went to 1000." He stated that he tried to regain the engine's power but was unsuccessful. He said he changed the airplane's flight path to try to land on a closer runway but could not maintain altitude. The pilot reported, "...A few seconds after this I was on the ground." According to a Federal Aviation Administration Safety Inspector, the airplane came to rest on the ground about one half of a mile west of the airport. Examination of the accident site revealed that there were marks and slashes on a homes' rooftop near where the airplane came to rest. The airplane came to rest about 90 feet from the house. Examination of the airframe revealed no anomalies. The airplane was removed from the accident site and put into storage by Alphin Aircraft of Hagerstown, Maryland. The engine was inspected at the storage facility under the supervision of a FAA Safety Inspector. The examination revealed the presence of fuel throughout the engine and fuel system. Alphin personnel reported there was a total of about 10 to 15 gallons of fuel in the tanks. Ignition and control continuity were verified. The linkage from the throttle, propeller, and mixture controls to the engine were examined and no anomalies were noted. The last annual inspection was done November, 1993 and the airplane was operated 43 hours since then.