Event Description
Witnesses observed the aircraft during takeoff ground run, noting that the engine sputtered and backfired. The takeoff roll was described as long and slow. As the aircraft passed the terminal building, it was in a slow-speed, high-pitch attitude, and the engine RPM appeared to decrease. Subsequently, the aircraft descended behind a line of trees.
Post-Accident Inspection
Following the accident, investigators examined the aircraft. The fuel system contained auto gas, and no Supplemental Type Certificate (STC) authorizing the use of auto gas was found for the aircraft. Inspection of the engine revealed several exhaust valve anomalies:
- The #2 exhaust valve was visibly warped.
- The #3 exhaust valve guide was broken and moved with the stem upon removal.
- The #4 exhaust valve was tight in its guide.
Compression testing showed that the #2 cylinder had zero compression.