On March 15, 2004, at 0730 central standard time, a Beech A36 single-engine airplane, N789SA, was substantially damaged during a forced landing to a field following a loss of engine power five miles north of the Lone Star Regional Airport (CXO), near Conroe, Texas. The commercial pilot and one of two passengers sustained serious injuries. The other passenger sustained minor injuries. The airplane was registered to and operated by the pilot. Instrument metrological conditions (IMC) prevailed, and an instrument flight rules (IFR) flight plan was filed for the 14 Code of Federal Regulations Part 91 business flight. The cross-country flight originated from CXO at 0725, and was destined for Wichita, Kansas. The 2,500-hour pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that the day prior to the accident flight, he requested that the local fixed base operator (FBO) refuel the airplane with 10 gallons of fuel in each wing tip tank, and top off the main fuel tanks. On the day of the accident, prior to departure, the pilot received his IFR clearance to depart runway 14, turn east and climb to 2,000 feet mean sea level (msl). After departure, upon reaching 2,000 feet, the engine lost power. Despite multiple attempts, the engine would not restart. The pilot stated that he was in IMC until descending through the cloud layer at 200 feet above ground level (agl), before he "spotted a small field, approximately 150 feet wide by 400 feet long." The pilot added that he "put the airplane into a left slip to lose altitude, and extended the landing gear." The airplane landed hard, spun around approximately 90 degrees, and came to rest up right in the field. The passenger seated in the right front seat stated that as the airplane was climbing through the clouds, he noticed a "slight engine misfire, followed soon by another misfire." As the climb continued, the passenger observed the "cylinder temperature indication was on the extreme right, pegged out." As the pilot initiated a turn back to the airport, "the engine missed, and seized up." The pilot rated passenger seated in the rear seat facing backwards stated that he did not see the pilot conduct the preflight, but the pilot mentioned to him that he checked the oil. The passenger checked the fuel tanks to see if "the fuel instructions had been completed, and the mains were full and the tip tanks were half full." At this time, the passenger "did not notice anything unusual." The passenger informed the pilot that he had some work to finish and wanted to sit in the cabin. Due to the request of the pilot, he sat in one of the seats facing backwards. The passenger also stated that as the pilot started the engine "no unusual sounds" were heard." While the pilot was going through his checklist, "the engine quit," and the pilot commented "hmm, never done that before." The pilot restarted the engine, and taxied out to the run-up area. Shortly after takeoff, the passenger added that he noted "the humming of the engine was not the humming sound that he was used to hearing in that [air]plane." The engine was "starting to misfire and sputter," as the passenger observed the pilot turning back toward the airport. At an altitude of 2,000 feet, "the engine quit." An aircraft flight line employee of the FBO where the airplane was last refueled reported that he "simply made a mistake and placed the wrong fuel into the aircraft in question." His initial training to work on the flight line started on Sunday, March 14, 2004, the day before the accident, and throughout that day, he assisted in the refueling of a Hawker 800 jet, and a Pilatus PC-12 turbine powered airplane. At 1400, near the end of his scheduled work shift, his supervisor requested that he fuel and hangar N789SA. After receiving his instructions, he went to the fuel truck that he had previously used during the day, and proceeded to refuel the accident airplane. The flight line employee serviced N789SA with 10 gallons of Jet-A fuel in each wingtip tank, and 33 gallons in both wing fuel tanks. The employee stated that he had previously been trained on the differences between Jet-A and 100 Low Lead aviation fuel and the different aircraft that use each, but "did not realize that the fuel truck only contained Jet-A fuel." Examination of the airplane by the FAA inspector, who responded to the accident site, revealed that both main landing gears were crushed upward through both wing structures. The engine was partially separated from the airframe, and the fuel selector was observed in the "right" position. Examination of the aircraft fuel tanks revealed both wingtip tanks and main tanks were breached. A sample of fuel extracted from the airplane was "consistent with Jet-A fuel." At 0753, the automated weather observing system at CXO reported the wind calm, visibility 1/2 statute mile, 100-foot indefinite ceiling, temperature 59 degrees Fahrenheit, dew point 59 degrees Fahrenheit, and an altimeter setting of 30.08 inches of mercury.