On March 23, 1985, a Cessna 175 (registration N6710E) was involved in an aviation accident near Sonora, TX. Investigators recorded the probable cause as: Failure of the No. 3 connecting rod due to oil starvation resulting from a clogged oil passageway. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Aircraft registered N6710E. Photo: redlegsfan21 from Vandalia, OH, United States / CC BY-SA 2.0, via Wikimedia Commons
An aircraft was destroyed during a forced landing in rough terrain after an engine failure in flight. Investigation found the No. 3 connecting rod failed due to oil starvation from a clogged oil passageway.
Overview
An aircraft was completely destroyed when it executed a forced landing on rough terrain following an engine failure that occurred in flight. The loss of engine power necessitated the emergency landing, which resulted in the total destruction of the aircraft.
Investigation Findings
During the investigation, the No. 3 connecting rod was examined and found to have failed. The cause of the failure was determined to be a lack of lubrication, known as oil starvation. Further inspection of the oil system revealed that the passageway supplying oil to that connecting rod was obstructed by sludge and fine metal particles. Additionally, the engine's oil filter and oil screen were also obstructed by similar debris. In addition to the oil system issues, the investigators found several broken piston rings and leaking hoses in the intake manifold. The aircraft was being fueled with automotive gasoline and used Marvel Mystery Oil as an additive.
Probable cause
Failure of the No. 3 connecting rod due to oil starvation resulting from a clogged oil passageway.
