What happened
While cruising at 13,500 feet MSL, the pilot of a Piper 32RT 300T heard a loud bang, followed by a total loss of engine power. Oil from the engine sprayed onto the windshield, obscuring the pilot's vision. The pilot secured the engine and identified a dirt strip located near an automobile salvage yard as a suitable forced landing area. During the landing sequence, the aircraft struck an automobile.
The investigation
During the preliminary examination, investigators discovered a hole in the engine crankcase near the number 1 and number 2 cylinders. Upon disassembling the engine, it was revealed that the number 1 and number 2 connecting rods had broken. The bearing surface of the number 1 connecting rod showed evidence of a galled spot. Further inspection of the five remaining connecting rods showed evidence of galling between the connecting rod bearing face and the rod bearing.
Findings
According to the engine manufacturer, the observed galling between the connecting rod bearing face and the rod bearing is caused by periods of high loading, which can result from overspeed or excessive manifold pressure. Records indicated that approximately 15 days or 6 flight hours prior to the accident, maintenance personnel had adjusted the turbocharger wastegate. The pilot reported that there were no unusual instrument indications leading up to the engine failure.