On October 21, 2006, approximately 1150 central daylight time, a single-engine Piper PA-38-112 airplane, N2426N, was substantially damaged during a forced landing following a loss of engine power during cruise flight near Wimberley, Texas. The private pilot and his passenger were not injured. The airplane was registered to and operated by a private individual. Visual meteorological conditions prevailed and a flight plan was not filed for the 14 Code of Federal Regulations Part 91 personal flight. The cross-country flight originated from the Rusty Allen Airport (5R3), near Lago Vista, Texas, and was destined for the New Braunfels Municipal Airport (BAZ), near New Braunfels, Texas. The 201-hour private pilot reported in the Pilot/Operator Aircraft Accident Report (NTSB Form 6120.1/2) that he preformed a preflight inspection of the airplane and found "no mechanical irregularities." During the inspection the pilot noted that the oil level was at 6 quarts and the fuel level was at 14 gallons. The pilot further stated that at departure, about 11:15, he had 12 gallons of fuel on board. He then climbed to 2,500 feet with the electric boost pump in the "on" position. A few seconds later, while at cruise flight, the "engine powered back," and the pilot reported that he tried to reapply full power to the engine by checking the fuses and the [fuel] primer, as well as tuning "on" the electric fuel pump and selecting the left fuel tank position. The engine did not respond and the pilot elected to land in a field. During the forced landing the airplane crossed a dirt road and slid into a ditch, coming to rest in an upright position. During a telephone conversation with the NTSB Investigator-in-charge (IIC), the pilot stated that the engine "sputtered out" and "then came back, sputtering again", before "quitting completely." According to a Federal Aviation Administration (FAA) inspector, who responded to the accident site, the aircraft received structural damage during the forced landing. The inspector also noted that the airplane's left wing fuel tank appeared empty, and the right wing tank contained a "little" fuel. During the airplane salvage retrieval, recovery personnel reported they drained 7 gallons of fuel from the right fuel tank and that the left tank was empty. An engine examination was conducted on November 15, 2006. The engine sustained minimum impact damage during the accident. The engine was rotated by hand; continuity through the engine's valve train and compression on each cylinder was established. The bracket air filter (part number 4106) was in place, and appeared in good condition and free of obstructions. The airplane's electrical system was turned on and the electric fuel boost pump was switched on; the electric pump appeared to operate normally. Approximately two tablespoons of fuel was drained from the carburetor bowl. The gascolator was opened and found to be dry and clear, the screen at the top of the gascolator was in-place and free of any debris. The left magneto was timed at 24 degrees and the right magneto was timed at 20 degrees. The magnetos were rotated by hand and each magneto produced a spark at all terminals. Additionally, the right magneto's castle nut was found threaded approximately halfway on, and missing its cotter pin. The top sparkplugs were removed and appeared normal, and had light gray deposits in the electrode area. The amount of engine oil remaining in the engine could not be determined since the oil level was below the end of the oil dipstick. An engine run was conducted on December 29, 2006 under the supervision of the NTSB IIC. Due to damage sustained during the accident sequence, a fuel line was connected directly to the engine-driven fuel pump from a fuel container. Additionally, the mixture control arm was bent and wired to the full rich position and metal stiffeners were added to strengthen the damaged engine mount. The magnetos were reinstalled and timed, and four quarts of oil was added to the engine. The engine was started and ran rough. After the engine was shutdown, the number three cylinder was found to be "cold." Both ignition leads to the number three cylinder were found to contain cuts in the wire as result of the accident. The ignition lead from the right magneto was replaced. Before the engine was run again, a compression check was preformed and all four cylinders showed normal compression. During the second engine run, the engine was run at various power settings including full power. The engine ran for approximately 10 minutes with no abnormalities noted. Piper's PA-38-112 pilot manual states under Fuel Limitations: "...The unusable fuel for this airplane has been determined as 1.0 gallon in each wing in critical flight attitudes." Additionally, the manual states that fuel consumption during cruise flight should be 6.5 gallons/hour (75%, Best Power setting). At 1155, the automated weather observing system at HYI, approximately 10 miles southeast of the accident site, reported wind from 230 degrees at 6 knots, 10 miles visibility, scattered clouds at 4,000 feet, temperature 75 degrees Fahrenheit, dew point 63 degrees Fahrenheit, and an altimeter setting of 29.89 inches of Mercury.