NTSB Factual Report

On September 12, 2004, about 1330 eastern daylight time, a Cessna 172B, N7422X, experienced a loss of engine power during cruise flight, and was substantially damaged during a forced landing near Wiscasset, Maine. The certificated private pilot and passenger were not injured. Visual meteorological conditions prevailed and no flight plan had been filed for the flight that departed Greenville Municipal Airport, Greenville, Maine, destined for the Wiscasset Airport (IWI), Wiscasset, Maine. The personal flight was conducted under 14 CFR Part 91.

The pilot reported that he was about 2 miles west-northwest of IWI, at an altitude 1,000 feet msl, when the engine suddenly began to lose oil pressure. Thirty seconds later, the engine quit, and he performed a forced landing to a field. During the landing, the airplane struck trees and flipped over.

Examination of the engine by a Federal Aviation Administration inspector revealed oil in the engine compartment and an oil leak that originated from the seal where the oil filter adapter attached to the crankcase. A subsequent teardown of the engine reveled that the number 1 connecting rod was fractured and exhibited thermal signatures, consistent with high temperatures. Fragments of bearing and connecting rod material were located in the oil sump. The fragments were blackened, consistent with exposure to high temperatures. In addition, the crankshaft exhibited thermal damage and smearing on the number 1 and number 2 connecting rod journals.

The engine had been operated for about 1,450 hours since it was last overhauled. The most recent annual inspection was conducted on October 1, 2003, about 65 hours prior to the accident.

NTSB Probable Cause

The failure of the oil filter adapter seal, which resulted in a loss of oil pressure, and subsequent catastrophic engine failure, and forced landing.