ERA24LA198

The failure of the nose oil seal to remain secure in the engine crankcase, which resulted in a loss of engine oil and partial loss of engine power.

The pilot reported that when attempting to climb from his cruise altitude to an altitude at which he could begin a practice approach, the engine began to run rough and climb performance deteriorated. He discontinued the practice approach and turned direct to the airport; checking his instruments, he saw that the engine oil pressure was low and "in the red.” While proceeding to the airport, the engine performance continued to degrade, and the pilot was unable to maintain altitude. About 2 miles from the airport, the pilot realized he would not be able to make the runway and performed a forced landing in a field. The airplane sustained substantial damage to the fuselage during the landing. Postaccident examination of the engine found the nose oil seal was protruding about 3/8 inch out of the recess in the crankcase, which allowed engine oil to be expelled from the crankcase and resulted in the loss of oil pressure. The crankshaft main journals and bearings and the rod journals and bearings exhibited light scoring. This was likely due to the lack of oil for lubrication and resulted in the power loss that the pilot experienced as the journals and bearings began to overheat. The engine had been operated for about 6,089 hours during the 19-year period since its last overhaul. The engine manufacturer recommended overhaul at 12 years or 2,000 hours of operation, whichever occurred first. Had the engine been overhauled in accordance with the engine manufacturer’s recommendations the nose oil seal would have been replaced, and it is likely that it would have remained secure.

On April 29, 2024, about 1645 eastern daylight time, a Cessna 172P, N99442, was substantially damaged when it was involved in an accident near Palatka, Florida. The commercial pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he was about to begin a practice instrument approach and was near the initial approach fix for the RNAV RWY 9 instrument approach to Palatka Municipal Airport (28J), Palatka, Florida. In preparation for the approach, he added power to climb from 2,500 ft mean sea level (msl) to 3,000 ft msl. Shortly after adding full power the engine began to run rough and climb performance was less than expected. He surveyed the engine instruments and noticed that the oil pressure was reading low (in the red), and that the engine was only producing partial power. Unable to maintain altitude, the pilot abandoned the practice approach and attempted to fly directly to the runway, which was about 10 miles away. He reported that about 2 miles short of the runway his altitude was about 500 ft msl, so he elected to make an off-airport landing in a field that had recently been logged. The airplane came to rest upright on rough terrain in a field of tall grasses and sapling pine trees. Postaccident examination of the airplane by a Federal Aviation Administration (FAA) inspector found substantial damage to the fuselage. The FAA inspector also reported that both wing fuel tanks were full of fluid consistent with 100 LL aviation fuel, and when sampled, no water was observed in either wing fuel tank. Further examination of the airframe found control continuity from all flight control surfaces to the flight controls in the cockpit. The fuel strainer screen was removed and examined. The screen was unobstructed and showed minimal organic debris. Postaccident examination of the engine found oil on the upper and lower surfaces of the crankcase, the surface forward of the forward engine baffles, and on the interior of the lower cowling. Epoxy sealant was found smeared on the upper area where the two crankcase halves met. The propeller was removed, and the crankcase nose oil seal was found protruding about 3/8 inch from its recess in the crankcase nose. Sealant material was observed smeared on the forward surface of the nose oil seal. About 2 quarts of oil was drained from the engine. The faces of all four hydraulic tappet bodies in the right crankcase half exhibited significant corrosion pitting. The faces of three of the four hydraulic tappet bodies in the left crankcase half exhibited significant corrosion pitting. The crankcase was split to facilitate further examination. The crankshaft main journals and rod journals exhibited light scoring. The crankshaft main bearings and the rod bearings also exhibited light scoring. Review of maintenance records showed the engine had accumulated 20.3 hours of time in service since the last 100-hour inspection. The records also show the engine had accumulated 6,089 hours and 19 years of time in service since it was overhauled. Lycoming Service Instruction 1009BE states: “All engine models are to be overhauled within twelve (12) calendar years of the date they first entered service or of last overhaul. This calendar year time period TBO is to mitigate engine deterioration that occurs with age, including corrosion of metallic components and degradation of non-metallic components such as gaskets, seals, flexible hoses, and fuel pump diaphragms.” Service Instruction 1009BE also specifies the operating hour time between overhaul periods as 2,000 hours for the make and model engine. The owner/operator of the airplane failed to respond to questions about the maintenance and condition of the engine, and specifically about why it had not been replaced or overhauled.