HISTORY OF FLIGHT On August 5, 2000, at approximately 0800 central daylight time, a Piper PA-36-285, N57616, piloted by a commercial pilot, was destroyed when it impacted terrain near Osborne, Kansas. The 14 CFR Part 137 aerial application flight was not on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The pilot, who was the sole occupant, was fatally injured. The local flight originated from the Osborne Municipal Airport (K75), Osborne, Kansas, at an undetermined time. The aircraft was found resting in a soft field of wheat stubble 2.3 miles northeast of K75 at approximately 0815. The pilot had reportedly completed spraying of crops and was returning to K75 when the accident occurred. There were no reported witnesses to the accident. PERSONNEL INFORMATION The pilot was the holder of a commercial pilot certificate with airplane single engine land, airplane multi-engine land, and instrument-airplane ratings. He also held a certified flight instructor certificate with an airplane single engine land rating. The pilot's second-class aviation medical certificate was issued on May 10, 2000. According to the pilot's logbook, he had accumulated a total of 5,506 hours total flight time as of the last entry dated April 05, 1995. Of the hours listed in the logbook, 3,672 hours were in agricultural operations, and 1,083 were in PA-36 aircraft. The logbook had endorsements for biennial flight reviews with the most recent endorsement dated December 03, 1999. The pilot was also the holder of an airframe and powerplant mechanic certificate (A&P) with inspection authorization. AIRCRAFT INFORMATION The airplane was a Piper PA-36-285, serial number 36-7660015. According to the aircraft logbook and the recording tachometer, the airplane had accumulated a total of 4,063 hours time in service at the time of the accident. The most recent annual inspection was performed by the pilot/owner on November 22, 1999. According to the logbooks, the airplane had accumulated a total of 3,927 hours at the time of the inspection. A Continental 6-285-C2 engine that was rated at 285 horsepower powered the aircraft. According to the first entry in the engine logbook, the engine had accumulated 672 hours since new on June 01, 1993. Each logbook entry after the first entry referenced engine time since major overhaul. The engine was installed on the N57616 on October 04, 1995 at an engine time of 735.2 hours. The last entry, dated November 22, 1999, indicated that the engine had accumulated 1,103.0 hours. The logbook reviewed did not contain an entry for a major overhaul. METEOROLOGICAL INFORMATION The weather reporting station located at the Russell Municipal Airport, Russell, Kansas, recorded the weather at 0753 as: Winds direction 190 degrees Wind speed 10 knots Sky condition clear Temperature 72 degrees Fahrenheit Dewpoint 45 degrees Fahrenheit Altimeter setting 29.79 inches of mercury WRECKAGE AND IMPACT INFORMATION The aircraft impacted a soft plowed field about 2.3 miles and 032 degrees from the Osborne Municipal Airport, Osborne, Kansas. A global positioning system (GPS) receiver was used to determine the accident position. The GPS position was recorded as 39 degrees 27.618 minutes north, 98 degrees 39.267 minutes west. The ground scars indicated that the aircraft was headed west-southwest at the time of impact. The landing gear was separated from the airplane. The airplane came to rest pointed in a southerly direction. The left wing was curved upward. The right wing leading edge was crushed back. The right horizontal Stabilizer was bent down. The engine was partially separated from the fuselage. The pilot's body was found just outside of the cockpit on the right side of the aircraft. The seat belt cable and shoulder harness cable were found separated. The separated areas exhibited a 'broom straw' appearance consistent with tensile overload. The pilot was not wearing a helmet and the manual control for the shoulder harness inertia reel was found in the unlocked position. According to the aircraft service manual, "...When the manual control is placed in the locked position, the harness cable will no longer pay out, no matter what position the harness is in and no matter how much load is pulling on the cable... When the manual control is set in the unlocked (automatic) position, the pilot has freedom of movement for the upper part of his body with the reel automatically reeling in and out. However, the reel will lock automatically in any position upon application of more than 2 1/2 [plus or minus] 1/2 G inertia load on the reel." The engine and accessories were examined and the fuel injection throttle linkage was found broken. The fuel manifold valve was disassembled. The diaphragm was found intact and fuel and foreign material was found in the chamber. The foreign material was similar in consistency to the polyurethane foam material installed in the fuel tanks. Piper service bulletin number 713, dated May 11, 1981, states that field reports of deterioration of the foam within the fuel tanks had been received. The SB calls for inspection of the fuel cells, and replacement of the foam material if it is found to have deteriorated. The remainder of the engine was examined and the number four cylinder was found to be compromised. A portion of the piston pin was protruding through a hole in the cylinder wall. The engine was removed from the aircraft and shipped to the Teledyne Continental Motors (TCM) facility in Mobile, Alabama, for a teardown inspection. Details of the examination are found under the heading "TESTS AND RESEARCH" in this report. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot at the Brock's North Hill Mortuary, Hays, Kansas, on August 06, 2000. A Final Forensic Toxicology Fatal Accident Report prepared by the Federal Aviation Administration was negative for all tests performed. TESTS AND RESEARCH The engine was disassembled at TCM under the direct supervision of a NTSB investigator. Upon disassembly, it was found that the number four piston pin was protruding through the cylinder wall and the piston skirt was fractured. Additionally, the number four cylinder intake valve was fractured. Recovered pieces of the piston and intake valve were sent to the NTSB materials laboratory in Washington, D.C. for further examination. No other anomalies were found that could be associated with a preexisting condition. The NTSB materials laboratory report indicates that the intake valve fracture exhibited signatures consistent with overstress. The report indicates that portions of the piston skirt had fractured and separated from the piston. The fracture surfaces on the piston contained severe mechanical damage that obscured the fracture surface features. One side of the piston skirt exhibited damage consistent with the piston rotating about the piston pin and the connecting rod impacting the skirt. ADDITIONAL INFORMATION After the examination was complete, the engine was returned to a representative of the owner's insurance company on February 27, 2001. The number four piston and intake valve were returned to a representative of the owner's insurance company on May 31, 2001. Parties to the investigation were the FAA Wichita, Kansas, Flight Standards District Office, and Teledyne Continental Motors.