On July 26, 1993, at 1920 eastern daylight time (EDT), a Beech BE-19, N1976W, registered to Mark C. Goodwin of Birmingham, Michigan, and piloted by a private pilot, was substantially damaged during an off airport forced landing onto a railroad track roadbed. Visual meteorological conditions prevailed at the time of the accident. The personal 14 CFR Part 91 flight was not operating under a flight plan. The pilot and two passengers reported minor injuries. The flight originated from Birmingham, Michigan, at 1915 EDT. According to the pilot's statement on NTSB Form 6120.1/2, he performed a normal runup prior to takeoff. Shortly after takeoff the pilot said he felt the airplane decelerating as it passed over the end of the departure runway. He stated he checked the airplane's attitude, throttle, carburetor heat, mixture and fuel setting. He said the airplane's engine continued to lose power and that he was forced to land on a railroad roadbed between two railroad tracks. A Birmingham, Michigan, police department report stated the pilot said the airplane was approximately 150 feet above the ground when it began to descend. The police report contained the account of three witnesses who observed N1976W approaching the area where it made a forced landing. The report stated: "...they heard the engine slow and saw the plane bank to the south going down toward the ground." The on-scene investigation was conducted by a Federal Aviation Administration (FAA) Principal Maintenance Inspector (PMI) on July 27, 1993. His report states the airplane was not secure at the time of his arrival and "...two individuals were next to the aircraft, one of them on the right hand side of the fuselage close to the tail." The PMI's damage report is appended to this report. The PMI's inspection report stated: "The following systems were inspected: air/induction, ignition,and fuel... (were) found to be operating properly." The PMI's report also stated the fuel pickup screens were free of contaminants, the carburetor float bowl was drained and it "... contained auto fuel." The metal carburetor float did not have visible cracking on its surfaces. The PMI asked the owner of the airplane if he had fueled it with auto fuel. According to the PMI's written statement, "The owner stated that he serviced the LH wing tank with six gallons of auto fuel on Monday, July 26, 1993... ." During the second interview on August 3, 1993, the owner stated he had added six gallons of auto fuel to the left fuel tank on July 23, and July 24, 1993. The owner of the airplane stated he had purchased auto fuel from a local service station. An investigation into the fuel source found it is listed as 87 octane and, according to the services station's supplier, the fuel purchased on July 24, 1993, had ten percent ethanol in it. The fuel supplier's statement is appended to this report. The PMI's investigation found that N1976W had not been modified for auto fuel use. A second FAA PMI interviewed the airplane's owner regarding the use of auto fuel. During this interview, the PMI stated the owner informed him that he was aware of the auto fuel STC requirements, but did not acquire one for the accident airplane because it was not available. The owner stated the engine was approved for auto fuel and that is why he was using it in the airplane. Further investigation by the PMI revealed that an STC for the Beech BE-19 is not available. The PMI interviewed an STC applicant who attempted to obtain an STC for the BE-19. The PMI stated the applicant's tests found the airplane's engine would not operate on auto fuel due to severe vapor lock. The vapor lock was caused by a number of items according to the applicant: length of fuel lines, number of bends in the fuel lines, fuel tank venting, and the cowl's internal temperature.