On December 9, 2004, a Mooney M20F (registration N3208F) was involved in an aviation accident near Fabens, TX. Investigators recorded the probable cause as: The loss of engine power as a result of the failure of a connecting rod due to oil starvation/exhaustion. A contributing factor was the lack of suitable terrain for the forced landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A private pilot with 600 hours experienced engine difficulties and loss of oil pressure, leading to an engine stoppage. He made an off-airfield landing on an interstate highway, but during flare, the right wing struck a semi-truck, causing the airplane to flip and come to rest inverted.
Accident Sequence
A private pilot with 600 flight hours reported that he began having engine difficulties. The pilot noticed the #2 cylinder head temperature gauge indicated a lower than normal temperature, and shortly thereafter, there was a loss of engine oil pressure. The pilot determined that no airport landing sites were available. A few minutes later, the engine stopped. He prepared to execute an off-airfield emergency landing, deciding that the safest place to land was the westbound lane of an interstate highway below him. During the landing flare, the right wing of the airplane collided with the rear of a large semi-tractor truck traveling on the highway. The airplane then flipped over and came to rest inverted.
Engine Examination
A certificated airframe and powerplant mechanic examined the engine under the supervision of an FAA inspector. The examination revealed that the connecting rod to the #2 piston was broken. The piston was seized inside the cylinder and could not be removed. No rod bolts or hardware were found. There was damage to the engine case between the #2 and #4 cylinders. The spark plugs were removed and inspected, and no anomalies were found. The oil filter and oil screen were removed, and metal flakes were observed. Oil was not observed on the dipstick or anywhere in the engine, nor did it appear on the exterior surface of the airplane.