What happened
While transiting the Atlanta area, a commercial rated pilot reported a sudden loss of engine oil pressure and severe vibration to Atlanta Approach Control. In response to the emergency, Approach Control vectered the aircraft toward the Dekalb-Peachtree airport for an emergency landing.
Due to the loss of power, the pilot was unable to maintain altitude and performed a forced landing on a highway. The aircraft was in a cruise configuration with the wheels and flaps retracted at the time of impact. Upon contacting the roadway, the aircraft slid along the road, first striking a Jeep Cherokee and then impacting a Mazda 626. Following the collision with the Mazda, both the aircraft and the automobile caught fire and were destroyed. The pilot sustained serious injuries, while the driver of the automobile was fatally injured.
The investigation
During a post-crash disassembly of the engine, investigators discovered that the number five connecting rod had fractured through the rod shoulder. A metallurgical examination of this component revealed fatigue cracks originating at or near areas of galling. It was noted that connecting rods are routinely re-used following inspections for evidence of such galling. At the time of the accident, the engine had operated to within approximately 60 hours of its recommended time between overhauls.