NTSB Factual Report

On August 24, 2010, about 1110 eastern daylight time, an experimental amateur-built Freeman Super Koala airplane, N220FF, owned and piloted by a commercial pilot, was substantially damaged when it impacted terrain during a forced landing following a loss of engine power during cruise flight near Traverse City, Michigan. Visual meteorological conditions prevailed at the time of the accident. The personal flight was being conducted under the provisions of Title 14 Code of Federal Regulations Part 91 without a flight plan. The pilot sustained minor injuries. The local flight originated from the Cherry Capital Airport, near Traverse City, Michigan, about 1050.

The pilot reported that during the climb he reduced power to 6,000 rpm about three to four minutes after takeoff. The pilot switched the fuel tank selector from the main tank to the auxiliary tank. The engine’s rpms subsequently dropped from 6,000 to 2,000 rpm. He switched the fuel tank selector back to the main tank and the engine’s rpms did not increase. He applied the choke and no increase in engine rpms was observed. According to the pilot, he attempted to execute a forced landing to the “only open space available.” The area which the pilot picked to perform the forced landing had rising terrain. He said that the left wing dropped and the airplane turned about 55 degrees to the left before impact. The pilot stated that the airplane Hobbs meter accumulated 0.4 hour since the start of the flight.

According to the pilot, the airplane had accumulated 49.5 hours of total airframe time at the time of the accident. The airplane’s airworthiness was maintained by the owner/pilot under a conditional maintenance program and the last conditional inspection was performed on February 18, 2010. The airplane was powered by a two cylinder, two-stroke, 50-horsepower Rotax 503 UL engine with serial number 360-5697. The engine was sold to the airplane's kit manufacturer in March of 1986 and according to the pilot, it had not been overhauled.

A Federal Aviation Administration inspector examined the wreckage. Engine control continuity was established. The engine’s fuel filters were clean. The number one cylinder exhaust port exhibited an accumulation of carbon. The number one cylinder’s spark plug could be loosened by hand and it exhibited a fouled appearance when it was removed.

The engine’s maintenance manual included an itemized maintenance plan that listed a "general overhaul of the engine" as planned and necessary maintenance. A supplemental note indicated that the overhaul is to be carried out every 5 years or every 300 hours, whichever comes first. The maintenance manual further indicated that the spark plugs are to be tightened on a cold engine to 240-inch pounds of torque.

NTSB Probable Cause

A loss of engine power due to the improper torquing of the number one cylinder's spark plug as a result of inadequate maintenance.