Incident Overview
At night, while en route to Northampton, Massachusetts, the airplane experienced an engine failure. The pilot executed an emergency landing in the parking lot of the University of Massachusetts Medical Center in Worcester, Massachusetts. During the landing, the aircraft collided with a car and a utility pole. The collision with these objects could not have been avoided.
Engine Examination
Following the incident, an examination of the engine was conducted. The inspection revealed that the oil pump had failed. The connecting rods were found to be overtempered, and the bearings of the connecting rods had failed.
Oil Pump Analysis
A bench binocular microscopic examination was performed on the drive and driven impeller fracture surfaces of the oil pump. The analysis showed that the impellers broke as a result of overstress separations. The driven impeller exhibited characteristics typical of a sintered-powder-metal component. The total time on this component was 1,828.0 hours. The drive impeller appeared to be machined from barstock (steel).
Service Bulletin Compliance
Service Bulletin SB-456C specified a time of compliance at next overhaul, not to exceed 2,000 hours with sintered iron gears. The driven impeller, with 1,828 hours, was within this limit.