MIA07LA120

The pilot performed a preflight inspection of the airplane which included checking the fuel tank for contaminants; none were found. He was operating the airplane using unleaded automotive fuel containing up to 10 percent ethanol. He then departed on a local pleasure flight and approximately 30 minutes later, the engine began to cough. He looked for a landing area and while doing so, the engine began sputtering and losing power. He maneuvered for a forced landing to a field but the flight was too high and fast. He then performed S type turns in an effort to land in another field but the right main landing gear contacted the ground causing the gear to collapse. Postaccident examination of the engine revealed the element of the in-line fuel filter was blocked by contaminant which restricted flow from the filter. Additionally, the in-line fuel filter was 3/4 full of water; however, the carburetor bowl was full of clean fuel. No evidence of preimpact mechanical failure or malfunction was noted with the engine. An FAA issued SAIB indicates that fuel containing alcohol can have an affect on fuel system components and should not be used. A Rotax Service Instruction indicates that fuel containing more than 5 percent alcohol is not to be used.

On July 12, 2007 about 1936 eastern daylight time, an experimental light sport aircraft John D. Williams XT-912, N133W, registered to and operated by a private individual, experienced a loss of power during cruise flight and was substantially damaged during a forced landing in a field near Newport News, Virginia. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 personal, local flight from Williamsburg-Jamestown Airport, Williamsburg, Virginia. The private-rated pilot, and one passenger sustained minor injuries. The flight originated about 1900, from Williamsburg-Jamestown Airport.

The pilot stated that the airplane was fueled no longer than 1 week earlier with unleaded automotive fuel that contained ethanol. A sticker on the fuel pump indicated the fuel may contain up to 10 percent ethanol. The aircraft was then operated on at least 4 flights before the accident flight. During his preflight inspection of the airplane before the accident flight, he checked the fuel tank for water; none was detected. After takeoff the flight proceeded to his intended sightseeing area, then elected to return. While flying along the entrance of the York River, the "...engine 'coughed' once or twice." He knew there was an adequate supply of fuel on-board, though he perceived the engine sound to be associated with either fuel starvation or fouled spark plugs. He immediately looked for a landing area and notified the Newport News/Williamsburg International Airport (KPHF) control tower of the problem. While doing so the, "...engine was sputtering, giving less and less performance, if any." He maneuvered the airplane towards the larger of two nearby fields, but the flight was too high and fast during final approach to the field. He performed S-type turns in an effort to lose altitude for landing in the second (smaller) field, but the right main landing gear contacted the ground causing collapse of the right main landing gear. The airplane slid to a stop and came to rest upright resting on its right side.

Examination of the airplane by the FAA inspector-in-charge revealed no evidence of propeller rotation at the time of impact. The fuel tank was found to contain approximately 2 gallons of automotive type fuel of a 90/10 blend of fuel and alcohol. No contamination was noted in the fuel tank. The fuel filter was noted to be 3/4 full of "...what was determined to be mostly water, with a thin layer of fuel on top. The fluid was murky, full of brown dirt-like particles, with an area of brown sediment 'baked-on' to the lower end of the glass housing." Disassembly of the fuel filter revealed the filter element was "...substantially clogged..." by a large number of dirt-like particles. The "dirt-like" particles were not further examined. Resistance was felt when attempting to blow air through the filter element. Examination of the carburetor revealed the float bowl was full of clean fuel; no sediment or water was noted. Rotation of the engine revealed crankshaft, camshaft, and valve train continuity. The spark plugs were examined and found to be clean with normal combustion deposits. An adequate supply of lubrication oil and coolant fluid was noted.

NTSB review of FAA issued Special Airworthiness Information Bulletin (SAIB) CE-07-06, dated October 27, 2006, revealed it contains information indicating that automobile fuels containing alcohol is not allowed in aircraft because in part, alcohol is corrosive and not compatible with the rubber seals and other materials used in aircraft, which could lead to fuel system deterioration and malfunction.

According to Rotax Service Instruction SI-912-016/SI-914-019, dated August 28, 2006, fuel with more than 5 percent alcohol added must not be used.