It was PIELSTICK medium speed 10 cylinder engine, free end side connected with auxiliary air compressor. At sea around 0800 hrs on a fine morning, heard big banging noise and saw a good volume of oil draining out from engine foundation.

Immediately stopped the engine by pushing shut down. After engine cooling down sufficiently C/case doors opened found 1st crankshaft balance weight fell down breaking the oil pan. After closer Investigation found crank shaft web projection sheared off and balance weight had come off the shaft. In that ship there is a provision to run the propeller by coupling G/Eng. at slow speed.

Disconnected coupling between M/Eng and reduction gear by removing the spare. It was suspected that cause of the damage may be due to attached engine driven air compressor, due to fatigue web projection sheared off.