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Engine Exhaust Valve Failure During Takeoff Leads to Forced Landing (N94740)

St. Paul, MN, US

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.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 2026-07-04Data APIEditorial standards

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.
Engine failure

Frequently asked questions

What happened in the 21 Apr 1985 Ercoupe (eng & Research Corp.) 415-CD accident near St. Paul, MN?

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.

What aircraft was involved and where did it happen?

The accident on 21 Apr 1985 involved an Ercoupe (eng & Research Corp.) 415-CD, registration N94740, at St. Paul, MN.

What was the probable cause of the accident?

Failure of the #3 exhaust valve (PN 3921) near the stem-head.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001214X36133. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.