On August 13, 1996, at 1822 central daylight time, a Cessna TR182, N6316T, registered to and operated by a private owner as a Title 14 CFR Part 91 personal flight collided with a causeway bridge while maneuvering near Port Isabel, Texas. Visual meteorological conditions prevailed for the cross country flight and a flight plan was not filed. The private pilot and the pilot rated passenger received fatal injuries and the airplane was destroyed. The flight originated from McAllen, Texas, at 1730. A review of the McAllen Air Traffic Control Tower and Corpus Christi Approach Control data, by the investigator-in-charge, revealed that the airplane departed the Miller International Airport and requested vectors by approach control to the Cameron County Airport for touch and goes. At about 1753, the pilot reported that he had the airport in sight. Approach control service was terminated and the pilot was given a frequency of 119.5 if he wanted further ATC service. The last communication from the pilot was about 1755 when he requested and received from approach control the Unicom frequency for the Cameron County Airport. During telephone interviews, conducted by the investigator-in-charge, and on the enclosed statements, witnesses and local authorities reported that the airplane was observed flying a pass from north to south under the Queen Isabel Causeway Bridge which spans between Port Isabel, Texas, and South Padre Island, Texas. The airplane made a 180 degree turn and approached the bridge toward the north for another pass; however, the airplane struck a concrete bridge pylon and column and descended uncontrolled into the water. Witnesses recalled an explosion and black smoke as the airplane struck the bridge. Portions of the vertical and horizontal stabilizer were found projecting from the bridge column at about 8 feet above the waterline. Texas Department of Public Safety divers located the fuselage submerged on the west side of the column in approximately 8 to 10 feet of water. See the enclosed reports from the Texas Department of Transportation, Texas Department of Public Safety, and the U. S. Coast Guard for additional details. The FAA records for the pilot-in-command and the pilot rated passenger, reviewed by the investigator-in-charge, revealed the following information. The pilot-in-command obtained the Private Pilot Certificate on April 4, 1988. The last third class medical certificate was issued on August 25, 1988, at which time the pilot reported a total of 600 flight hours. The pilot rated passenger obtained the Private Pilot Certificate on June 18, 1984, with his last third class medical certificate issued on May 30, 1986. Total flight time listed on his medical application was 2,700 hours. The FAA aircraft registration records revealed that the airplane was registered to the pilot-in-command on December 10, 1985. A review of the aircraft maintenance records, by the investigator-in-charge, revealed that the last annual inspection was performed and the airplane returned to service on July 27, 1995. The autopsy for the pilot-in-command was performed by Lawrence J. Dahm, M.D., at Harlingen, Texas, with autopsy toxicology screening performed by Dean F. Fritch, Forensic Toxicologist, at the National Medical Services, Inc., at Willow Grove, Pennsylvania. Aviation Toxicological testing was performed by the FAA Civil Aeromedical Institute (CAMI) at Oklahoma City, Oklahoma. The CAMI toxicological findings were confirmed positive for alcohol in the following concentrations: 143.000 mg/dL in the blood; 166.000 mg/dL in muscle fluid; and 65.000 mg/dL in vitreous fluid. The CAMI toxicology findings were confirmed positive for cocaine in the following concentrations: 0.133 ug/ml in the blood; and 0.114 ug/ml in liver fluid. See the enclosed toxicology report for additional alcohol and drug concentrations. The South Padre Island Police Department reported public intoxication convictions against the pilot-in-command and other criminal and traffic charges pending. The autopsy for the pilot rated passenger was performed by Margie W. Cornwell, MD, of Harlingen, Texas. Aviation Toxicological testing was performed by the FAA Civil Aeromedical Institute (CAMI) at Oklahoma City, Oklahoma. The CAMI toxicological findings were confirmed positive for marihuana and cocaine in the following concentrations: 0.006 ug/ml tetrahydrocannabinol in the blood; 0.006 ug/ml tetrahydrocannabinol carboxylic acid (marihuana) in the blood; 0.162 ug/ml tetrahydrocannabinol carboxylic acid in the urine; 0.087 ug/ml cocaine in the blood; 1.809 ug/ml benzoylecgonine in the blood; 16.203 ug/ml cocaine in the urine; and 277.950 ug/ml benzoylecgonine in the urine. See the enclosed toxicology report for additional drug concentrations. The Board neither took possession of the airplane nor examined any airplane components during the investigation.