On August 8, 1989, a Grumman American AA-5B (registration N28565) operated by Brown, Gerald B. was involved in an aviation accident near Terminal Island, CA. Investigators recorded the probable cause as: The valve had failed from fatigue due to overheating, which resulted from a worn or bell mouthed valve guide. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A single-engine aircraft experienced engine roughness and power loss over water. The pilot turned shoreward and executed a forced landing on a dirt road, colliding with a fence and parked cars. Investigation revealed exhaust valve failure due to fatigue from overheating caused by a worn valve guide.
Incident Overview
During an overwater flight to cross a 23-mile channel, the engine began to run rough and lose power. The pilot turned the aircraft toward the shore and performed a forced landing on a dirt road on Terminal Island. Before the aircraft came to a stop, it collided with a fence and several parked cars in a storage lot.
Engine Examination
An examination of the engine revealed severe battering on the top of the No. 1 piston and the No. 1 cylinder head. The No. 1 exhaust valve head had separated from its stem and was found lodged in the exhaust system. The exhaust valve guide was severely worn at the exhaust port, and the valve stem area was heavily corroded and coked with exhaust residue. A fatigue fracture was identified on a portion of the valve head that was not damaged by the collision.
Metallurgical Analysis
A metallurgical examination of the failed valve revealed evidence that the valve had failed from fatigue due to overheating. This overheating resulted from a worn or bell-mouthed valve guide.
Probable cause
The valve had failed from fatigue due to overheating, which resulted from a worn or bell mouthed valve guide.