HISTORY OF FLIGHT: On December 19, 1993, at 2300 central standard time, a Cessna 172M, N13051, sustained substantial damage near Lancaster, Texas, during an attempted takeoff. The instrument rated commercial pilot received fatal injuries and the sole passenger sustained serious injuries. Instrument meteorological conditions prevailed throughout the area for the local personal flight. The passenger stated that following the takeoff from runway 13 at the Lancaster, Texas, Municipal Airport the visibility was much less than it had seemed on the ground. He further stated the airplane appeared level as it was banking to the left. He looked out the right window of the airplane and thought they were flying low when the airplane impacted. The passenger said that "everything appeared normal with the airplane" prior to the accident. PERSONNEL INFORMATION: Pilot logbooks indicated a night flight on June 21, 1993, and an instrument proficiency check on July 17, 1993. The last logbook entry was November 1, 1993; however, relatives stated the pilot had flown a number of times, including some night flights, since that date. During telephone interviews, relatives reported the pilot drank a few glasses of wine at a social gathering and went Christmas caroling for several hours prior to the flight. They said the pilot decided to take his son for an aerial view of the Christmas lights. AIRCRAFT INFORMATION: Maintenance logbook entries were made on December 13, 1984, approving use of automotive fuel. However, FAA records did not contain Form 337 and placards for automotive fuel were not found installed on the airplane. Maintenance records did not indicate completion of service letters, service bulletins, or airworthiness directives for the carburetor. METEOROLOGICAL INFORMATION; A pilot of another airplane (enclosed statement) reported that at 2100 weather was overcast with a ceiling at 1,700 feet MSL to 1,500 feet MSL with a visibility of 4 to 5 miles and decreasing. Surface observations from Navy Dallas (21 miles northwest of the site) at 2255 reported ceilings from 500 to 700 feet above the ground with visibility from 5 to 7 miles due to fog. Airport elevation is 500 feet MSL. WRECKAGE AND IMPACT INFORMATION: Wreckage was found approximately one mile from the departure airport. The terrain was marked by trees 35 feet to 45 feet high. The distribution path (enclosed diagram) was on a measured magnetic heading of 090 degrees. Numerous broken limbs were found along the distribution path. The left wing came to rest in the 10 feet deep creek bed with the fuselage in an inverted position on the slope of the creek bed. Propeller hub and blades with yellow painted tips remained attached to the engine which came to rest 35 feet beyond the main wreckage. Both propeller blades exhibited scrapes and were bent aft. A slashed tree branch containing yellow smears was found 15 feet beyond the engine. The left wing leading edge was crushed aft to the main spar. A cedar twig was found wedged under an inspection panel screw on the lower surface of the left wing. A piece of material resembling the wood fibers was found wedged along the left wing skin. Fuel tank integrity was compromised. One gallon of fuel was obtained from the left fuel tank. Flight control continuity was established. MEDICAL AND PATHOLOGICAL INFORMATION; The Southwest Institute of Forensic Sciences at Dallas, Texas, performed the autopsy. The Southwest Regional Flight Surgeon, stated that the toxicological levels of ethanol detected are consistent with the ingestion of alcohol and would have caused impairment. A toxicological report is enclosed. TEST AND RESEARCH: An engine test run was conducted on December 21, 1993, at Air Salvage of Dallas in Lancaster, Texas. The engine was serviced with fuel taken from the left wing fuel tank. Due to an engine vibration and an oil leak, the engine run was discontinued. An examination revealed the crankshaft flange was bent. The engine run was continued; however, the run was limited to 1800 RPM due to the continued vibration. During the engine run, fuel was observed leaking from the carburetor. The carburetor MA4-SPA, P/N 10-50009, S/N BL-20-9883 was removed and found to contain a composite float P/N 30-759/47 which sank in the fuel originally obtained from the left wing of the airplane. The carburetor composite float was further examined (enclosed report) on December 28, 1993, at a FAA certified repair station by a Federal Aviation Administration (FAA) inspector. The composite float P/N 30-759/47 weighed 32 grams. New composite float specification weight is 17 to 23 grams. Other carburetor components were examined (enclosed report) on January 6, 1994, at a FAA certified repair station by the FAA inspector. Excessive wear was found on the throttle shaft. Wear and perforation was noted on the accelerator pump. Grooves were found along the needle surfaces. The accelerator pump discharge check valve P/N 36-540 leaked fuel during testing from 1 PSI through 6 PSI. ADDITIONAL INFORMATION: The airplane was released to the owner's representative.