HISTORY OF FLIGHT On November 28, 2000, at 1624 central standard time, a Landes/Karich/Schmidt Christen Eagle II, an experimental amateur-built airplane, N83007, was substantially damaged when it impacted terrain while maneuvering near Tyler, Texas. The two private pilots aboard the airplane were fatally injured. The airplane was registered to one of the pilots. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The local aerobatic flight departed the Tyler Pounds Field, Tyler, Texas, at 1600. According to one witness, who was located approximately 1/2 mile from the accident site, the airplane had completed about four hammerhead stalls and was conducting its fifth when the accident occurred. The witness, who was an aerobatic flight instructor and former Naval aviator, stated that the pilot was conducting his maneuvers below the scattered clouds that were in the area, which he estimated to be at 3,000 feet agl. During the four hammerhead stall maneuvers that he witnessed prior to the accident, he observed the airplane "climb straight up, the engine power went to idle, the airplane stalled and then dove nose down" toward the ground. On each occasion, as the pilot was recovering from the dive (approximately 200-300 feet agl), the witness heard the engine power being applied in order to climb and practice the next maneuver. The witness stated that on the last maneuver, the airplane flew "dangerously low," and he knew the accident was imminent as it disappeared behind the trees. PERSONNEL INFORMATION According to friends of both pilots, the front seat pilot would demonstrate or "instruct" aerobatic maneuvers to the rear seat pilot/aircraft owner. According to two witnesses, the pilot/aircraft owner was conducting an "airshow" for them at the time the accident. It was not possible to determine which of the two pilots was flying the airplane at the time of the accident. The front seat pilot held a private pilot certificate with airplane single-engine land and instrument airplane ratings. He was issued a third class medical certificate with no limitations on August 27, 1998. Review of the pilot's logbooks revealed that he had accumulated approximately 1,139 hours of total flight time, of which 27.1 hours were in the same make and model as the accident airplane. The pilot received an endorsement for his last biennial flight review on June 5, 1999, which was conducted in an aerobatic airplane. According to the pilot's logbook, he had been flying aerobatic aircraft on and off since 1987. The rear seat pilot also held a private pilot certificate with an airplane single-engine land rating. He was issued a second class medical certificate without limitations on June 29, 1999. Review of the pilot's logbooks revealed that he had accumulated approximately 289.5 hours, of which 36.5 hours were in the same make and model as the accident airplane. The pilot also logged approximately 76 hours in a T-18 aerobatic airplane; however, it is unknown whether aerobatic maneuvers were performed in that aircraft. The pilot was endorsed for his last biennial flight review on November 2, 2000, in the accident airplane. AIRCRAFT INFORMATION The aircraft completion date for the amateur-built, tandem-seat, bi-wing airplane was June 28, 1984. The airplane was issued a special airworthiness certificate on July 20, 1984. A review of the aircraft's maintenance records revealed that the aircraft underwent its last condition inspection on May 3, 2000, at an aircraft total time of 1,558.4 hours. The Lycoming AEIO-360-A1D 200-horsepower engine (serial number L-11504-51A) was overhauled on September 23, 1993, at a total time of 1,010 hours. At the time of the accident, the aircraft had accumulated 1,617.5 hours. No uncorrected discrepancies were noted in the maintenance records. METEOROLOGICAL INFORMATION At 1616, the Tyler Pounds Field weather observation facility reported the wind from 150 degrees at 6 knots; visibility 10 statute miles; a few clouds at 2,700 feet agl, scattered clouds at 3,200 feet agl, scattered clouds at 7,000 feet agl; temperature 70 degrees Fahrenheit; dew point 61 degrees Fahrenheit; and an altimeter setting of 30.02 inches of mercury. WRECKAGE AND IMPACT INFORMATION The FAA inspector, who responded to the accident site, stated that the aircraft came to rest upright in a level, open field. The initial ground impact mark displayed marks consistent with the main and tail landing gear. The aircraft sustained upward crushing damage from the bottom side. The engine was displaced up, aft, and to the right approximately 45 degrees. The throttle control was in the idle position and the mixture and propeller controls were in the full forward position at the accident site. The FAA inspector stated that he confirmed flight control continuity and noted that the propeller blades were twisted. PATHOLOGICAL INFORMATION Autopsies were performed on both pilots by the Dallas County Medical Examiner's Office. No pre-existing conditions were noted that would have contributed to the accident. A toxicology test for carbon monoxide, cyanide, ethanol, and drugs was conducted on each pilot by the Civil Aero Medical Institute in Oklahoma City, Oklahoma. The test results on the rear seat pilot were negative. The front seat pilot tested positive for 0.246 ug/ml of citalopram in the blood, 1.926 ug/ml of citalopram detected in the liver, and an unquantified amount of citalopram detected in the urine; 0.068 ug/ml, and 0.864 of n-desmethylcitalopram in the blood and liver respectively; and an unquantified amount of di-n-desmethylcitalopram was detected in the blood, and 0.484 ug/ml of di-n-desmethylcitalopram was detected in the liver. According to the FAA's Southwest Regional Flight Surgeon, citalopram (also known by the tradename Celexa) is a prescription antidepressant medication, and n-desmethylcitalopram and di-n-desmethylcitalopram are metabolites of citalopram. The use of citalopram would have precluded medical certification of this pilot had it been reported. Review of the pilot's past medical certificate applications showed that the pilot had not reported use of this medication to the FAA. ADDITIONAL INFORMATION According to Federal Aviation Regulation Part 91, Subpart D, Section 91.303, "No person may operate an aircraft in aerobatic flight...(e) below an altitude of 1,500 feet above the surface..." Both pilots were wearing parachutes during the accident flight and were utilizing three-point restraining systems. The aircraft wreckage was released to the owner's representative on January 1, 2001.