On July 16, 2001, at 0952 eastern standard time, an amateur-built Druine Turbulent D-31, N4697T, piloted by a commercial pilot, sustained substantial damage during an in-flight collision with the terrain during initial climb from runway 18 (3,600 feet by 60 feet, dry/concrete) at the Boone County Airport, Lebanon, Indiana. Visual meteorological conditions prevailed at the time of the accident. The personal flight was operating under the provisions of 14 CFR Part 91 and was not on a flight plan. The pilot, the sole occupant, reported minor injuries. The flight was originating at the time of the accident and had the intended destination of Owosso, Michigan. According to the pilot's written statement, he was having difficulties obtaining the recommended static engine rpm and had the propeller blade pitch adjusted prior to the accident flight. The pilot reported that, "After refueling the aircraft, I performed the preflight check, then I followed the engine start checklist, no defects noted, then the Before Takeoff checks, with all temps, pressures and RPM well within limits. On Takeoff roll at 65 kts. [knots] I lifted off maintaining 65 kts. on climb out at aprox. [approximately] 40-50 foot altitude, I gently lowered the nose to continue the climbout at 70 kts. At about the same time the aircraft experienced a sudden loss of forward thrust, with the engine continuing to run. I tried to maintain aircraft control to attempted to glide the aircraft back to the runway. The aircraft struck the ground about 20-25 feet right of the runway, turning about 180 degrees counter-clockwise, after impact." The pilot reported that a new ground adjustable propeller was installed and adjusted by an airframe and powerplant mechanic at the Boone County Airport. The piloted stated, "Suspect prop as cause of forward thrust loss." An inspector with the Federal Aviation Administration (FAA) performed the post-accident inspection of the airplane. No anomalies were found with the airframe or engine that could be associated with any pre-impact condition. The propeller was inspected and the adjustment screw was found with 18 threads showing, or an adjustment of about 5 full turns. According to the FAA inspector's statement, "This propeller is factory preset to a 35 [inches of helix advancement] pitch or "relaxed" position, the adjustment procedures call for five and one-half turns from neutral to get 18 [inches of helix advancement] pitch (minimum pitch) to 52 [inches of helix advancement] pitch (maximum pitch)."