On January 14, 1996, at 2006 central standard time, a Cessna 150M, N714JV, registered to and operated by a private owner as a Title 14 CFR Part 91 personal flight, was substantially damaged following a collision with power lines near Mandeville, Louisiana. The commercial pilot was seriously injured. Visual meteorological conditions prevailed for the night flight for which a flight plan was not filed. A witness observed the airplane approaching Interstate 12 from the north. As the airplane neared Interstate 12, it was observed executing a "left bank" and then went out of view. Several minutes later the witness observed a flash in the rear view mirror. The airplane struck unmarked power lines spanning Interstate 12 at highway 59. Firemen found the airplane entangled in downed power lines and the pilot was found lying under the interstate overpass. See enclosed report. Examination of the airplane by the FAA inspector revealed that both wings were structurally damaged, the empennage was displaced, and the left elevator had sustained damage. The left main landing gear was folded outward, the nose landing gear was folded under, and the engine was displaced downward. A fuel sample was taken, and it was light blue in color and clear. A test run of the engine was accomplished on January 25, 1996 at Teledyne Continental Motors, Mobile, Alabama. The engine operated normally. See enclosed report. The toxicology report from Lakeview Medical Center, Covington, Louisiana, revealed 0.172 percent Ethanol (alcohol) was detected in the pilot's blood from a specimen drawn at 2045, and 0.146 percent Ethanol was detected from a specimen drawn at 2230. These specimens were take on January 14, 1996, the day of the accident. See the enclosed report. Attempts to obtain a completed Pilot/Operator Report, NTSB Form 6120.1/2, were unsuccessful.