On July 5, 1995, a Champion 7ECA (registration N11064) was involved in an aviation accident near Lake Dallas, TX. Investigators recorded the probable cause as: The number one cylinder exhaust valve was stuck in the open position due to carbon buildup on the valve guide. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During takeoff on runway 17, the aircraft used about 2,000 feet to become airborne, appeared underpowered and slow, then the engine sputtered multiple times before the plane stalled and spiraled into water. Post-accident examination found the number one cylinder exhaust valve stuck open due to carbon buildup.
Accident Overview
A pilot performed an engine runup before commencing takeoff on runway 17. According to a witness, the airplane used approximately 2,000 feet of runway to become airborne. Another witness observed the departure and reported that it appeared to be underpowered and slow. A third witness reported that the plane passed overhead and the engine sputtered. The witness further observed the plane bank up and to the east, the engine sputtered twice again, and the plane stalled out, spiraling down into the water.
Engine Examination
An examination of the engine revealed that the number one cylinder exhaust valve was stuck in the open position due to carbon buildup on the valve guide.
Probable Cause
The stuck exhaust valve in the number one cylinder, caused by carbon buildup on the valve guide, resulted in a loss of engine power.