On April 21, 1985, an Ercoupe (eng & Research Corp.) 415-CD (registration N94740) was involved in an aviation accident near St. Paul, MN. Investigators recorded the probable cause as: Failure of the #3 exhaust valve (PN 3921) near the stem-head. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During climb after takeoff, the engine vibrated severely and lost partial power. In the ensuing forced landing, the right wing hit a tree and the nose gear collapsed. Post-incident inspection found the #3 exhaust valve had failed.
Flight Events
Shortly after takeoff, while the aircraft was climbing through approximately 700 feet above ground level, the engine developed a severe vibration and emitted a loud clanking sound. These indications were followed by a partial loss of engine power. The pilot initiated a forced landing.
Forced Landing and Impact
During the forced landing, the aircraft's right wing struck a tree. Subsequently, the nose gear collapsed as the aircraft contacted rough terrain.
Engine Examination
An examination of the engine revealed that the number 3 exhaust valve, part number 3921, had failed near the junction of the valve stem and head. The engine had accrued 1,040 hours in service since its last major overhaul.
Probable cause
Failure of the #3 exhaust valve (PN 3921) near the stem-head.