Casualties unknown

Engine Failure Due to Exhaust Valve Defect Leads to Forced Landing (N38428)

Douglas, MA, US

On August 31, 1990, a Piper J5 CUB (registration N38428) operated by John D. Bouchard was involved in an aviation accident near Douglas, MA. Investigators recorded the probable cause as: The failure of the number three exhaust valve, which caused internal engine damage and resulted in an in-flight engine failure. 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 2026-06-10Data APIEditorial standards

An aircraft experienced an in-flight engine failure at 2000 feet due to a failed exhaust valve, resulting in a forced landing where the right wing struck a tree.

What happened

The aircraft was operating at a cruise altitude of 2000 feet MSL when the engine suddenly ceased functioning. The pilot immediately began searching for suitable terrain to execute a forced landing. However, no appropriate site could be located in the immediate vicinity. During the subsequent descent and landing attempt, the right wing of the airplane struck a tree.

The investigation

Following the incident, a mechanical examination of the engine was conducted to determine the root cause of the failure. The inspection revealed significant internal damage within the engine assembly. Specifically, the #3 exhaust valve was found to have failed.

Findings

The technical analysis confirmed that the failure of the #3 exhaust valve was the primary factor leading to the internal engine damage and subsequent loss of power. This mechanical failure occurred during cruise flight, leaving the pilot with insufficient altitude and options for a safe landing.

Probable cause

The failure of the number three exhaust valve, which caused internal engine damage and resulted in an in-flight engine failure.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X24123. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.