On August 22, 1995, a Mooney M20K (registration N1154L) was involved in an aviation accident near Roundup, MT. Investigators recorded the probable cause as: an engine failure due to foreign object ingestion into the oil pump. A ruptured oil inlet screen contributed to the accident. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot reported an engine surge and loss of oil pressure while cruising north of Roundup, Montana. The engine failed, leading to a forced landing in a field. Postaccident examination found a metal chip in the oil system.
Incident Details
While cruising approximately 28 miles north of Roundup, Montana, a pilot experienced a momentary engine surge, after which the engine returned to normal RPM. Shortly thereafter, the pilot observed that the oil pressure had dropped to zero. The pilot turned the aircraft toward the Roundup airport to attempt an emergency landing. About three minutes later, the engine failed completely, and the pilot determined that reaching the airport was not possible. The aircraft subsequently performed a forced landing in a field located 9 miles north of Roundup. During the landing roll, the airplane passed through a barbed-wire fence.
Engine Examination
A postaccident examination of the engine was conducted. The inspection revealed a metal chip located between the oil inlet screen and the oil pump inlet. The oil inlet screen was split open along its solder seam, and the oil pump inlet exhibited gouging. A scanning electron microscope analysis determined that the chip consisted of copper-plated steel, a material characteristic of components used in engine gears and the camshaft. Additionally, Teledyne Continental reported that the oil screen appeared to have experienced an axial compressive load at an undetermined point in time.