What happened
While flying approximately 25 miles east of the destination airport, the pilot reported hearing a ticking sound lasting about two seconds, followed by complete engine failure. The pilot attempted to stop the engine for 10 to 15 seconds due to concerns that the engine might detach from the aircraft.
The pilot subsequently executed a forced landing in a field. During the approach, the airplane struck a tree, causing one wing to separate from the airframe. The aircraft traveled approximately 150 feet before coming to a final stop. The occupants were not injured.
The investigation
An engine teardown was conducted under the supervision of the FAA. The inspection revealed that all four connecting rod caps had separated from their respective rods. Additionally, the rod bolt nuts were discovered lying at the bottom of the oil pan.
Findings
The investigation determined that a mechanic had installed two modified rod caps without the connecting rod assemblies. These components were installed without being inspected or serviced prior to their installation on the engine.