Shortly after takeoff, the engine crankshaft expansion plug dislodged, and oil started to cover the airplane’s windscreen. The pilot attempted to return to, and land on the departure runway; however, the airplane subsequently touched down more than halfway down the runway. The pilot was unable to stop the airplane and it went off the runway and struck a chain link fence, which resulted in substantial damage to the fuselage, vertical stabilizer, and both wings. The crankshaft expansion plug was installed during maintenance that was performed 3 days prior to the accident. The mechanic who performed the maintenance stated that he installed the crankshaft plug using a ball peen hammer; instead of following the procedures outlined by the engine manufacturer; which called for the use of a special tool to properly deform and seat the plug. The mechanic said that he has used a ball peen hammer in the past to install crankshaft plugs with success; however, in this instance, the plug did not seat properly, dislodged, and allowed oil to exit the end of the crankshaft in flight.