ERA13LA262

The pilot reported that the airplane was in cruise flight at 9,500 feet mean sea level when he heard a loud noise and then popping sounds coming from the engine. He then smelled smoke and saw oil trailing from the engine compartment down the outside of the airplane. As the pilot maneuvered for a forced landing at a nearby airport, the engine produced intermittent power and then lost power completely. The pilot maneuvered the airplane for landing, but the runway was obstructed by cars and farm equipment, so he landed the airplane long. After touchdown, the pilot maneuvered the airplane into a small knoll between the airport and an elementary school where it struck a berm and came to rest. Postaccident examination of the engine revealed that the No. 2 cylinder exhaust valve was stuck and that its associated pushrod was bent, worn through, and fractured as a result of compression loading near its midpoint due to the stuck exhaust valve. Examination of the cylinder and its associated parts revealed that the exhaust valve guides were misaligned during manufacture, which subsequently resulted in the valve guide wearing unevenly, the valve sticking, the pushrod breaking, and the subsequent total loss of engine power.

On May 30, 2013, at 1628 eastern daylight time, a Cessna 182P, N6525M, was substantially damaged during a forced landing following a total loss of engine power while in cruise flight near Brevard, North Carolina. The private pilot incurred minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the flight, which departed Paulding Northwest Atlanta Airport (PUJ) Atlanta, Georgia, about 1520. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91.According to the pilot, while in cruise flight at 9,500 feet above mean sea level (msl), he heard a "loud noise," the manifold pressure gauge needle "rotated," and then heard a "bop-bop-bop" sound. The pilot reported that during the subsequent descent and search for a forced landing site, he smelled smoke and engine oil trailed down the outside of the airplane. The engine continued to produce power intermittently, until losing all power around 5,000 feet msl, about 3,000 feet above ground level. At the time of the engine power loss, the airplane was over a private airstrip in Brevard, North Carolina. The pilot maneuvered the airplane for landing on runway 4, but the runway was obstructed by cars and farm equipment that was harvesting hay from the airport property. After touching down, the pilot maneuvered the airplane into a small knoll between the airport and an elementary school where it struck a berm and came to rest. Inspection of the airplane at the accident site by a Federal Aviation Administration (FAA) inspector revealed substantial damage to the engine firewall, but no obvious reason for the loss of engine power. The airplane was retained for a detailed examination. The pilot held a private pilot certificate with a rating for airplane single engine land. His most recent third class medical certificate was issued August 31, 2011. The pilot reported 1,500 total hours of flight experience, of which 500 hours was in the accident airplane make and model. According to FAA and maintenance records, the airplane was manufactured in 1975. Its most recent annual inspection was completed July 1, 2012 at 8,209 total aircraft hours. The airplane was equipped with a Continental O-470S engine with Superior Air Parts Millennium cylinders installed at its most recent overhaul. The engine's most recent overhaul was performed on November 1, 2000, and the engine had accrued 590 total flight hours since that date. Initial inspection of the engine revealed no obvious engine damage, so the engine was prepared for a test run by replacing the damaged propeller, plumbing a can of fuel into the fuel system, and using an external battery for engine start. The engine started immediately and idled, but made a "popping sound." The engine was stopped, and closer inspection revealed that the number 2 exhaust push rod tube was broken and leaked oil. The number two cylinder was removed, the exhaust valve was found stuck in the closed position andthe push rod was found to be worn through into the oil channel, and fractured at the midpoint. The cylinder and its associated parts were then shipped to the NTSB Materials Laboratory in Washington, DC. Detailed examination of the cylinder and its associated parts showed that the exhaust valve was stuck in the closed position. The exhaust pushrod was bent and fractured near its midpoint and the fracture signatures were consistent with compressive loading. The pushrod was worn through approximately 60 percent of its diameter. Examination of the cylinder revealed that the opening of the exhaust valve guide appeared circular, but the hole was not concentric with the exterior of the guide. The center of the hole was offset toward the center of the cylinder relative to the guide center axis. The measurements and the wear patterns exhibited a misalignment of the valve guides and the contact between the pushrod, rocker arm, valve stem, valve head, and seat. The cylinders were delivered fully assembled to the overhaul facility, and a search of the FAA Service Difficulty Report database revealed no reports for the engine cylinder assembly.