HISTORY OF FLIGHT On May 11, 2011, at 0947 eastern daylight time, a Hawker Beechcraft Corporation F33A, N17825, was substantially damaged during a runway overrun following an aborted takeoff at Rock Airport (9G1), Tarentum, Pennsylvania. Visual meteorological conditions prevailed and no flight plan was filed for the local orientation flight. The certificated private pilot and one passenger were seriously injured, while the two other passengers received minor injuries. The flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Prior to the accident flight, the airplane departed Butler County Airport/K W Scholter Field (BTP), Butler, Pennsylvania, about 0900, after it was serviced with 2.5 gallons of fuel, which filled the tanks. The pilot flew 12 nautical miles to 9G1, where the airplane landed uneventfully about 0925, taxied to parking, and shutdown. The accident airplane was one of several involved in a Young Eagles event that day to introduce students to general aviation. According to witnesses, the airplane began its takeoff roll at the approach end of runway 17, which was 3,550 feet long. They described the airplane as it accelerated down the runway, lifted off, climbed a few feet, and settled back on the runway. The airplane "swerved" as it slowed, and then overran the departure end of the runway and 100 feet of the grass overrun area. Skid marks began approximately 712 feet prior to the end of the runway. Witnesses said the airplane "almost" stopped on the overrun, but crested a steep, 30-degree embankment, and rolled about 100 feet to the bottom where it struck a culvert and came to rest. The pilot declined to be interviewed, and did not provide a written statement. WRECKAGE AND IMPACT INFORMATION The airplane was examined at the site and all major components were accounted for at the scene. Control cable continuity was established from the flight control surfaces to the cockpit area. The right wing leading edge exhibited damage across the inboard half of the wing and remained attached at all attachment points. The right aileron and flap remained intact and attached to the wing. The left wing leading edge exhibited crush damage on the entire front section of the wing. The left aileron remained attached at both hinges and the push rod and the left flap remained attached. The flaps were in the retracted position confirmed by the measurement of the flap actuator. The main landing gear were locked in the down position and the inboard landing gear doors were closed. The landing gear control handle was in the down position and the landing gear actuator was in the down position. The horizontal stabilizer, elevator, vertical stabilizer, and rudder remained attached to the fuselage with no damage noted. The elevator trim setting was approximately neutral. All seats were equipped with lap belts and shoulder harnesses. All shoulder harnesses were intact. All lap belts remained attached to their respective attachment points. The left front seat lap belt exhibited no obvious damage and was found in the most extended position. The right front seat lap belt operated normally and was in the most extended position. The left rear seat lap belt exhibited no obvious damage. The right rear seat shoulder harness remained attached to the lap buckle. The right rear seat lap belt exhibited no obvious damage. First responders stated that only the passenger in the right rear seat wore a shoulder harness. All shoulder harnesses and inertial reels operated normally when tested. All seats were found in the most upright position. The engine was retained and examined at a later date. PERSONNEL INFORMATION According to the Federal Aviation Administration (FAA) records, the pilot held a private pilot certificate with ratings for airplane single-engine land and instrument airplane. His most recent third class medical certificate was issued in October 2009. The pilot reported 2,300 total hours of flight experience, of which 1,700 hours were in the same make and model as the accident airplane. The pilot accrued 12 hours of flight time in the 30 days prior to the accident. AIRCRAFT INFORMATION According to FAA records, the airplane was manufactured in 1977, and registered to the pilot in 1998. It was a four-seat, low-wing, retractable gear airplane that was equipped with a Teledyne-Continental Motors IO-550-B42, 300-horsepower engine. The most recent annual inspection was completed on April 12, 2011, at 4,851.7 total airplane hours. The airplane was modified with a JL Osborne Tip Tank supplemental type certificate (STC), which increased the total fuel capacity of the airplane to 120 gallons. METEOROLOGICAL INFORMATION The 0935 recorded weather observation at BTP, located approximately 12 miles northwest of the accident location, included winds from 090 degrees at 8 knots, clear skies, 10 miles of visibility, temperature 18 degrees C, dew point 6 degrees C, and an altimeter setting of 30.03 inches of mercury. The calculated density altitude for the airport at the time of the accident was 1,661 feet. AIRPORT INFORMATION Rock Airport was located about 12 miles northeast of Pittsburgh, Pennsylvania, at 1,063 feet elevation. The airport was not tower-controlled. The asphalt runway was, 3,550-feet-long, 100-feet-wide, and oriented 17/35. TESTS AND RESEARCH The handheld video camera, handheld global positioning system (GPS), and engine data monitoring system were forwarded to the NTSB Recorders Laboratory in Washington, DC. Examination did not reveal any data relevant to the accident. Engine Examination The engine was examined at the manufacturing facility in Mobile, Alabama, on June 13, 2011. The crankshaft was rotated by hand, valve train continuity was confirmed, and thumb compression was established on all cylinders. The oil filter and fuel filter were void of any debris. The top spark plugs were removed, all exhibited normal wear, and were light gray in color. The engine was prepared for an engine run and several impact-damaged engine components were repaired or replaced to facilitate engine operation. The engine started on the first attempt and ran without misfiring. The engine throttle was rapidly advanced from idle to full throttle several times and the engine performed without hesitation or interruption in power. The engine was run for approximately 20 minutes and then shut down. Weight and Balance Weight and balance calculations were performed using weight and balance information provided by the pilot, the actual weights of the occupants, the baggage recovered at the scene, and 110 gallons of fuel. The manufacturer's center of gravity range at maximum gross weight was 82.1 to 86.7 inches aft of datum. The manufacturer's maximum allowable takeoff weight was 3,400 pounds; however the airplane was modified with a JL Osborne Tip Tank STC, which increased the maximum takeoff weight to 3,600 pounds. Calculations revealed the airplane weighed 3,830.5 pounds at takeoff, with a center of gravity at 87.63 inches aft of datum. No published center of gravity limit data existed for weights above maximum takeoff weight. Performance Calculations The airframe manufacturer used the weather conditions present at the airport at the time of the accident, and the weight and balance data calculated to formulate an accelerate/stop distance for the accident airplane. At 3,400 pounds, the total distance for the airplane to accelerate to the recommended rotation speed and abort the takeoff to a stop was 2,171 feet. The extrapolated accelerate/stop distance at 3,830.5 pounds was 2,483 feet.