Crankcase explosions in propulsion diesel engines result from __________.

Correct Answer: Option A — the ignition of unburned fuel and air in the crankcase

Crankcase explosions are caused by the ignition of an explosive mixture of atomized lubricating oil mist and unburned fuel vapor within the enclosed crankcase when exposed to an abnormal localized hot spot, such as an overheated bearing or piston scuffing.