On July 08, 2007, about 1545 eastern daylight time, an experimental Zenair CH701 single-engine airplane, N7654Z, was substantially damaged during a forced landing following a loss of engine power after take-off near Huntington, Pennsylvania. The private pilot, sole occupant of the airplane, was not injured. The airplane was registered and operated by the pilot. Visual meteorological conditions prevailed for the personal flight conducted under 14 Code of Federal Regulations Part 91. No flight plan was filed for the local flight. The flight was originating at the time of the mishap. The 5,450-hour private pilot reported that following takeoff from Runway 18, and while leveling-off at pattern altitude, the 80-horsepower engine experienced a partial loss of power when he reduced the engine power from climb to cruise power. The engine RPM continued to decay and was unresponsive to any actions that the pilot took. The pilot added that he continued to descend with partial power and elected to execute a forced landing to a farmer's field. The airplane was unable to reach the selected field and the pilot elected to slow the aircraft to the lowest possible speed before impacting the trees. The aircraft came to rest in the upright position and the pilot was able to exit the airplane unassisted. An FAA airworthiness inspector examined the airframe and engine. He sampled the fuel from the carburetor bowl and gascolator and noted that the fuel was in the "changing phase and water beads were visible." Further inspection revealed structural damage to the airframe and propeller. The inspector established mechanical and valve train continuity through manual rotation of the engine and no known anomalies where found that would have prevented normal engine operation. Further examination and subsequent engine ground runs revealed that the engine was unable to achieve maximum power at full throttle and that the engine power would decrease significantly when switching the ignition selector switch to the right side. The FAA inspector noted that the RPM decay was demonstrated on multiple occasions. Additional research revealed that the aircraft was non-compliant with a manufacturing service bulletin (#44), dated August 28, 1995. The service bulletin stated that the ROTAX 912 engines have been known to experience an occasional malfunction of the ignition system. The report noted that the vibration of the engine could break the wires which run from the electronic module and the rubber isolator mounts. The aircraft was in storage for several years, to include the date that the service bulletin was released. The electronic ignition system, which included the ignition box (containing 2 ignition modules, 4 ignition coils and high voltage wires), one stator, and a pickup coil set, were shipped to the manufacture research laboratory for further examination. A resistance value check was preformed on all components with all readings well within the manufacture's specification. All wiring was inspected and no damage was found. The ignition box was bench tested to verify the correct function and the ignition box performed normally in all aspects including correct timing, voltage output, etc. The ignition module was subjected to heat with no change in performance or function. The laboratory analysis report indicated no problems were found with any of the components shipped for testing. The reason for the loss of engine power could not be determined. The pilot held a private pilot certificate with ratings for airplane single engine land, single engine sea, rotorcraft-helicopter, and instrument airplane. His last FAA third class medical was issued in November 2006. The pilot had accumulated a total of 5,450 hours, with 45 hours in the same make and model aircraft. Weather reported at Altoona-Blair County Airport, 23.1 nautical miles northeast of Hilling International Airport, was wind from 290 degrees at 9 knots, visibility 10 statute miles, clear skies, temperature 82 degrees Fahrenheit, dewpoint 59 degrees Fahrenheit, and a barometric pressure setting of 29.94 inches of Mercury.