Official report: ATSB Transport Safety Investigation Report; Marine Occurrence Investigation no. 229
On a loaded mini-bulk carrier sailing close to coast, a low pressure alarm sounded for the main engine lube oil system. When the duty engineer changed over to the standby filter, the lube oil pressure dropped quickly and the main engine shut down. At the time, all electrical power was being supplied by the main engine driven shaft generator, and so with the main engine shutting down, all electrical power was also lost. Power was restored quickly using an auxiliary generator, and when the main engine was restarted, the main engine low lube. oil pressure alarm sounded again. After stopping the engine, the chief engineer carried out a main engine crankcase inspection and saw flecks of metal in the bottom of two of the crankcase spaces. Suspecting major damage to the bearings, the ship requested towage into the nearest port.
Investigations revealed that the gudgeon pin in no. five piston had failed and that the piston skirt was damaged.
Root cause/contributory factors
Undetected pre-existing flaw, causing fatigue cracking of the gudgeon pin;
Metal debris from the failed gudgeon pin and piston skirt caused the lube oil filter to choke;
Standby filter had not been primed and low lube oil pressure damaged the bottom end bearing;
Evidence suggests that the lube oil pump had been running in a damaged condition for some time before the engine breakdown led to the pump's failure being discovered.
Result of investigation
The engine manufacturer did not provide sufficient guidance for monitoring the fatigue life of the gudgeon pin or inspecting the gudgeon pin for early signs of impending failure.
The maintenance for a critical piece of equipment, the main lube oil pump, was not planned according to the manufacturer's recommendations, despite the fact that a previous failure had occurred.
The shipboard procedures and practices for operating, maintaining and monitoring the lube oil filter were inadequate. The standby filter was not checked to ensure that it was ready for use and the in-service filter's condition was not adequately monitored.
Source article nautinst.
