On July 7, 1991, a Cessna 140 (registration N3160N) operated by Jack W. Potter was involved in an aviation accident near Montague, CA. Investigators recorded the probable cause as: THE FAILURE OF AN EXHAUST VALVE IN THE ENGINE. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During cruise, a loud banging noise from the engine led to a forced landing. On rollout, the airplane hit a berm and nosed over. Examination found a broken exhaust valve with over 973 hours of use.
Introduction
An incident occurred during a cruise flight when the pilot perceived a loud banging noise originating from the engine compartment. The pilot reported that he was unable to maintain altitude and subsequently executed a forced landing.
Sequence of Events
Upon touchdown and during the rollout, the airplane struck a berm, causing it to nose over. The airplane came to rest in an inverted position. No further details regarding the landing gear or airframe damage were provided in the source.
Engine Examination
Following the incident, a detailed inspection of the engine was performed. The examination identified a broken exhaust valve on the number one cylinder. Records indicated that this valve had accumulated at least 973 operational hours prior to the accident.