Bad valve leads to crash

This August 2010 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.

Aircraft: Grumman American AA-5A. Injuries: None. Location: Lakeview, Ore. Aircraft damage: Substantial.

What reportedly happened: The pilot reported that the preflight run-up was uneventful. Shortly after takeoff, at approximately 150 feet above ground level, the engine suddenly lost power.

The pilot verified fuel quantity, and attempted to lean the engine. Despite his efforts, the problem persisted, and he initiated a forced landing into a nearby field.

During the landing roll, the airplane’s left wing hit a fence post, and its empennage collided with high sage brush.

Examination of the engine revealed low compression within the No. 3 cylinder. Further examination revealed that the exhaust valve was stuck in the full open position.

Probable cause: A partial loss of engine power during the initial climb due to a stuck exhaust valve.

For more information: NTSB Identification: WPR10LA424

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