NYC85FA244

While en route at 5000' MSL, the plt transmitted that he had an eng problem & requested clearance to land at the providence/theodore francis green state arpt, which was aprx 12 mi away. The plt then asked the controller if that was the closest arpt; however, due to the radio congestion, the controller had difficulty understanding the plt. Vectors were provided to the providence arpt. Subsequently, the acft crashed across an interstate highway aprx 2 mi from the arpt while on a heading in that direction. During the crash landing, the acft collided with a concrete divider/barrier. An investigation revealed that the eng crankshaft, pn 639243, had failed from fatigue at two locations. The forward failure was thru the crankcheek between the #2 main bearing journal & the #3 connecting rod crankpin. The aft failure was thru the crankcheek between the #4 connecting rod crankpin & the #3 main bearing journal. Both fatigue cracks had subsurface origins.