HISTORY OF FLIGHT On October 24, 1999, at 1752 central daylight time, a Sturges Spezio Sport amateur-built experimental airplane, N75JS, was destroyed following impact with power lines while maneuvering near Mathis, Texas. The airline transport rated pilot and his pilot rated passenger were fatally injured. The airplane was owned and operated by the pilot. One of the four occupants of the automobile was seriously injured and three sustained minor injuries. Visual meteorological conditions prevailed for the 14 Code of Federal Regulations Part 91 personal flight, for which a flight plan was not filed. The local flight originated from the Arrowhead private airstrip near Lagarto, Texas, at an undetermined time. According to witnesses traveling on Interstate Highway 37, the airplane was observed flying "very low" toward the east before turning to the south over I-37. The airplane was observed in a "continuous descent" and the witnesses "thought that the airplane was attempting to land on the south-bound lanes of I-37." The airplane's landing gear impacted a set of power lines running perpendicular to the interstate, veering the plane to the left. Subsequently, the airplane impacted another set of power lines and was "flung nose down onto the north-bound lanes of I-37." The witnesses stated that the airplane and the automobile collided and then slid off the road to the east. The wood and composite airplane was fragmented in several sections as it came to rest atop and adjacent to the car. PERSONNEL INFORMATION The pilot held an airline transport pilot certificate with an airplane multiengine land rating, and a commercial certificate with an airplane single engine land rating. Additionally, he held a flight instructor certificate with airplane instrument, single and multiengine land ratings. The pilot's logbook revealed that he had accumulated a total of 17,658.2 flight hours, of which 20.3 hours were in the accident airplane. The pilot was issued a third class medical certificate on April 24, 1998, with a limitation to wear corrective lenses. AIRCRAFT INFORMATION The tail-wheel equipped, tandem-seat airplane was manufactured by a private individual on August 16, 1975. The airplane received a special airworthiness certificate at an aircraft total time of 65 hours on June 19, 1979. In August 1983, the aircraft was parked in a hangar. On May 8, 1992, the airplane underwent a condition inspection and was sold to another individual on June 10, 1992, at an aircraft total time of 99.8 hours. On June 7, 1999, the aircraft underwent its most recent condition inspection at an aircraft total time of 242.5 hours. At the time of this condition inspection, the Lycoming O-290-G1B engine underwent a top overhaul. According to Textron Lycoming, the O-290-G1B engine that was installed on the accident airplane was identified by serial number as a ground power unit engine that was not approved for installation on type certificated airplanes. This type of engine was manufactured during the World War II time frame. METEOROLOGICAL INFORMATION At 1751, the weather at Corpus Christi (located 27 miles southeast of the accident site) was reported to be sky clear, 10 statue miles visibility, wind from 090 degrees at 9 knots, temperature of 75 degrees Fahrenheit, dew point of 43 degrees Fahrenheit. WRECKAGE AND IMPACT INFORMATION According to the FAA inspectors, who examined the wreckage, the integrity of the fuel tanks was compromised. The engine was separated from the airplane and no fuel was found in the lines. There was no reported fire at the accident site. Review of wreckage photographs revealed that the cockpit was destroyed and the wings were separated from the fuselage. TESTS AND RESEARCH DATA On October 28, 1999, the engine was examined at a salvage facility by two FAA airworthiness inspectors and a representative of the engine manufacturer. According to the engine manufacturer's report, the two-bladed, fixed-pitch propeller was attached to the engine. One propeller blade sustained damage on the leading and trailing edges and its tip was curled back 90 degrees. The other propeller blade was curled and twisted at the tip. The magnetos were attached to the engine and the timing position was marked with white paint. The spark plugs were removed and reattached to their respective ignition leads. The crankshaft was rotated manually and the left magneto produced a spark in all 4 of its spark plugs. The right magneto produced a spark on the #2 and #4 bottom spark plugs but did not produce a spark on the #1 and #3 top spark plugs. Crankshaft continuity was confirmed to the accessory gears, and thumb compression was noted on the #1, #3, and #4 cylinders. The #2 cylinder would not produce thumb compression and was removed for examination. Dirt was noted in the exhaust valve area, which prevented the exhaust valve from closing completely. The #2 cylinder components displayed no anomalies. The carburetor throttle body remained attached to the engine oil sump; however, its bowl was broken off and destroyed and the venturi was missing. The carburetor inlet fuel screen was removed and found clean upon inspection. PATHOLOGICAL INFORMATION An autopsy on the pilot was performed at the Nueces County Medical Examiner's Office. There was no evidence found of any pre-existing conditions that would have contributed to the accident. Toxicological tests on the pilot for carbon monoxide, cyanide, volatiles, and drugs were conducted at the Civil Aeromedical Institute in Oklahoma City, Oklahoma. Results of the toxicological tests were negative. ADDITIONAL INFORMATION The Brownsville sectional chart depicts numerous power lines running parallel and perpendicular to I-37 in the area north of Mathis, Texas. The power lines that the airplane contacted were not highlighted with marker balls. The wreckage was released to the owner's family on June 6, 2001.