Primary finding
Probable cause
A total loss of engine power due to a combination of mechanical engine anomalies. Contributing to the accident was inadequate maintenance that failed to identify the engine anomalies.
Investigator assessment
Analysis narrative
The pilot departed on a local flight with two passengers. Several witnesses reported that they heard the airplane’s engine backfiring and sputtering and subsequently heard the engine quit. The surviving passenger, who was seated in the front right seat, stated that the engine lost power and there was nowhere to land. The airplane subsequently impacted heavily wooded terrain about 1 mile from the departure airport. Postaccident examination of the engine revealed that the No. 7 cylinder intake valve was stuck open. The No. 2 cylinder front spark plug was defective, and the Nos. 2- and 4-cylinders’ ignition wires were frayed, worn, and displayed arcing, which likely led to erratic operation or a lack of ignition in these two cylinders. The culmination of these issues most likely led to the engine running rough, backfiring, and subsequently losing total power. An annual inspection was accomplished on the airframe and engine about 2 months before the accident. General maintenance practices and the inspection should have identified the anomalies that were found during the postaccident engine examination.