Cessna 150H N22278 accident near Washougal, Washington

Probable cause

A loss of engine power during initial climb due to a stuck exhaust valve.

NTSB analysis

The pilot reported that the airplane’s engine lost power immediately after takeoff from a private airfield. The left wing then struck a large tree and the airplane subsequently crashed into wooded terrain, which resulted in structural damage to both wings and fuselage. Post accident examination of the engine disclosed that the (top) electrode areas of the spark plugs were oil soaked, and severe wear was noted to the ground and center electrodes. Further examination revealed that the number 4 cylinder exhaust valve was stuck in the open position. The valve remained stuck during a functional check and was later removed utilizing a punch and heavy hammer. A dark brown material and smearing was noted along the exhaust valve neck. Comparable material and smearing was observed along the interior surface of the exhaust valve guide. No additional mechanical anomalies were noted with the engine.

Text from the NTSB. Open the NTSB docket for WPR09LA364 for the full record.