Engine Oil Loss Leads to Collision During Go-Around (N4300Y)

Accident Summary

The pilot reported that during cruise flight, the left engine began to lose oil pressure. Air traffic control provided vectors to the nearest airport. As the left engine ran increasingly rough, the pilot shut it down while on final approach to Runway 3. The pilot then realized that the landing gear would need to be extended manually but did not have enough time to do so. Instead, the pilot attempted a go-around. During this maneuver, the aircraft collided with terrain past the end of the runway.

Engine Inspection

An inspection of the left engine revealed the reason for the oil loss. The crankshaft oil seal had come out of its bore in the crankcase and had moved forward on the crankshaft. Further examination showed that the oil seal was a 'lipped' type, which was not an approved seal for this particular crankcase. The unapproved seal allowed oil to escape, leading to the loss of oil pressure and subsequent engine roughness that prompted the shutdown.