On September 1, 1991, a North American NAVION A (registration N91736) operated by Milligan, Lewis D. was involved in an aviation accident near Chehalis, WA. Investigators recorded the probable cause as: The number one piston connecting rod had fractured. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Shortly after takeoff, the pilot heard a loud bang and lost engine power. A forced landing was made off the runway, impacting young Christmas trees. Investigation found a fractured connecting rod.
Sequence of Events
Immediately after retracting the landing gear following takeoff, the pilot heard a loud noise emanating from the engine compartment. This was accompanied by a complete loss of engine power. At the time of the failure, the aircraft was approximately 200 feet above the runway. The pilot executed a forced landing, bringing the aircraft to rest just beyond the departure end of the runway. During the flare, the aircraft struck numerous small Christmas trees planted in that area.
Investigation Findings
Subsequent examination of the engine revealed that the number one piston connecting rod had fractured. The fracture of this component was identified as the cause of the loud bang and the subsequent loss of engine power. No other mechanical anomalies were reported in the investigation.
Probable cause
The number one piston connecting rod had fractured.