Lessons Learned: Main Engine Failure Causes Fire

The MARINE ACCIDENT INVESTIGATION BOARD UK, published an investigation report which detailed the events related to a fire in the engine room onboard a vessel, due to failure of main engine components, initiated by fatigue fracture of the connecting rod small end bearing.

WHAT HAPPENED?

On a RO-RO vessel, propelled by a controlled pitch propeller powered by a medium speed 4 stroke marine diesel engine, the connecting rod  small end bearing of the one of the engine units failed, causing fracture of the con rod, the big end and small end bearings and fracture of the crankshaft. This caused a combination of stresses on components of the other units of the engine and a fire in the engine crankcase due to sparks caused by friction between metallic components.

The vessel was proceeding for her intended voyage after carrying out cargo operations , crew change and some maintenance and repairs at port. Soon after departing from port and after maneuvering operations, the second engineer handed over the watch to third engineer.

When the third engineer proceeded to carry out engine room rounds he heard loud noise and felt a strong vibration. There was an immediate blackout and the emergency generator cut in to supply power to the emergency equipment  onboard.

The visibility of the engine room almost reduced to zero and the third engineer made a good decision to use the emergency escape for his exit from the engine room. He took a deep breath and escaped the engine room from the emergency escape located on the aft of the engine room.

All engine room fire detection monitors were triggered. The crew mustered at muster station acted immediately by shutting the quick closing valves, activating the emergency stops and closing the vents and flaps of the engine room blowers.  Upon masters orders the Fixed CO2 system was activated, and the fire was extinguished.

The prompt response of the vessels crew caused the fire to be extinguished. Fixed CO2 system was used to fight the fire.  The casualties included third engineer who suffered from lung damage due to inhalation of toxic vapors but was fortunate to survive.

WHY IT HAPPENED?

The connecting rod fractured at the bolted shank flange, that is the Small End Bearing.

The engine parts were not replaced by the original manufacturer or their accredited service agents, as was the requirement of the manufacturer. The friction marks, and liner damage patterns were studied. The components that fractured were well within their running hours and examination and metallurgical testing eliminated any design and material defects.

The upper half of the connecting rod small end bearing/ the piston pin bearing revealed that there was fatigue failure at the small end bearing which caused the fracture and hence the splitting apart of various components in reaction to the imbalance in forces.

The incorrect bush removal and fitting process would have caused the introduction of notches which over time caused fatigue failure.

• The small end bearing had never been serviced by the manufacturer but by other agencies which were outsourced
• The ductile properties of the material were below the range specified and required by the manufacturer
• Other small end bearings were checked by the manufacturer and some were found to have notches and cuts and some localized heat marks.

DAMAGES SUFFERED

The main engine suffered severe structural damages

• Ruptured crankcase structure on port and starboard side, units 5,6
• Crankcase doors were thrown far apart from the main engine
• the con rod of unit 5, the big end bearing and part of the piston pin were thrown out of the ruptured crankcase structure
• Piston of unit 5, was ejected out of the other side of the crankcase
• Some parts of the bottom end bearing and piston pin upper bearing were even found in the bilge
• Cylinder head ruptured , with valves thrown in various directions.

LESSONS LEARNT

The engine parts were not replaced by the original manufacturer or their accredited service agents, as was the requirement of the manufacturer. The outsourced agency which carried out the overhauls did not have access to the makers manuals and some critical procedures.

It is necessary that the chief engineer and all other engineers be aware of the procedures of overhaul of various parts of the engine and any outsourced service providers have proper supervision while carrying out the jobs.

A proper record of the overhauls and the parts overhauled was not maintained. it was difficult to asses and trace the history of maintenance and checks related to critical equipment.

A detailed description of various jobs performed must be accurately maintained.

In the above case, prompt actions were taken by the crew which limited the fire as well as extinguished it quickly. The emergency equipment were well maintained and tested which led to the emergency generator quickly coming on load.

The third engineer however, did not carry an EEBD (Emergency escape breathing device) while on his escape out of the engine room. This can be attributed to factors such as low visibility which restricted him from seeing where the EEBD was located.

All crew must be aware of the location of fire fighting and life saving appliances onboard the vessel. The EEBDs are generally located at all exits and stairways on the engine room. In case of a mishap like the above, the crew must be well aware where to find the LSA and FFA, such as portable fire extinguishers and EEBD.

The crew must also be familiar with and well trained in the use of LSA and FFA, such that they can take prompt actions when in an emergency.

RECOMMENDATIONS 

Continuous survey of Machinery must be recorded and the record maintained for the critical and class related equipment. A clear and auditable record of such machinery and components

Staff training to be reviewed  and recorded such that the crew members are aware of the appropriate engineering methods of overhaul/replacement of parts and procedures and any updates regarding the same.

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