ERA17LA019

The private pilot reported that, about 3 hours into a cross-country flight, an instrument panel warning sounded and the oil pressure indicator was in the red arc; however, the engine continued to run smoothly. The pilot began to look for airports or fields to divert to and notified air traffic control of the abnormal engine indication. A few minutes later, the pilot heard "clanging" noises from the engine and it subsequently lost partial power. The engine was not producing enough power for the airplane to fly to the destination airport, and the pilot performed a forced landing in a field. During the forced landing, the airplane sustained substantial damage. Examination of the engine revealed that the No. 3 cylinder exhaust valve had stuck in the closed position, which resulted in failure of the cylinder's valvetrain components, breach of the rocker box cover, and the engine's oil supply being exhausted through the breached rocker box cover. The resulting oil starvation subsequently resulted in a partial loss of engine power.

On October 9, 2016, about 1050 central daylight time, a Cessna 182T, N65903, was substantially damaged during a forced landing in a field, following a partial loss of engine power during cruise flight near Toone, Tennessee. The private pilot was not injured. The personal flight conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed for the flight that that originated from Destin Executive Airport (DTS), Destin, Florida, about 0730. The flight was destined to McKeller-Sipes Regional Airport (MKL), Jackson, Tennessee.The pilot reported that while in cruise flight at 4,000 feet mean sea level, nearing the destination airport, an instrument panel warning sounded and the oil pressure indicator was in the red arc; however, the engine was running smoothly. The pilot began to look for airports or fields to divert to and notified air traffic control (ATC) of the abnormal engine indication. The pilot then requested, and ATC approved a direct course to the destination airport. A few minutes later, a light "clanging" noise was heard from the engine and the pilot alerted ATC that the airplane did indeed have an engine problem. The controller then advised the pilot that there was a private airstrip 5 miles west of his position and the pilot attempted to divert to that airstrip. The "clanging" noise grew louder and the engine did not have enough power to reach the private airstrip. The pilot then performed a forced landing in a field. During the landing, the airplane encountered uneven terrain, which collapsed the nose landing gear. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed that the firewall had sustained damage. The inspector also noted that the engine's No. 3 cylinder had suffered a catastrophic failure. Examination of photos provided by the inspector revealed evidence of oil on the exterior of the engine and exhaust system in the immediate vicinity of the No. 3 cylinder. The inspector added that the No. 3 cylinder exhaust valve was stuck in the closed position. The No. 3 cylinder was retained and forwarded to the NTSB Materials Laboratory, Washington, D.C. Examination of the No. 3 cylinder revealed that the rocker arm shaft bosses, bushings, and exhaust valve keeper were fractured. The rocker arm cover was fractured and bent outward. All of the fracture surfaces exhibited features consistent with overstress failure. No indications of pre-existing damage, such as corrosion or fatigue cracking, were observed. Dimensional review of the stuck exhaust valve revealed that it exhibited deposits on its surface up to 0.006-inch thick. The four-seat, high-wing, fixed-tricycle gear airplane was manufactured in 2004. It was equipped with a Lycoming IO-540, 230-horsepower engine. The airplane's most recent annual inspection was completed on July 12, 2016. At that time, the engine had accumulated 2,188.6 hourssince new. The airplane had flown 79.8 hours from the time of the inspection, until the accident, which resulted in 2,268.4 total engine hours since new at the time of the accident. The manufacturer recommended overhaul time for the make and model engine was 12 years or 2,000 hours, whichever occurred first. Review of an engine data plot for the accident flight reveled that the engine monitor was indicating that the No. 3 cylinder was about two-thirds below the exhaust gas temperature and cylinder head temperature of the other five cylinders during the entire approximate 3-hours cruise portion of the accident flight.