ll09 main engine damage a4
TRANSCRIPT
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8/10/2019 LL09 Main Engine Damage A4
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CODAN MARINE
MAIN ENGINE DAMAGEToolbox of Knowledge: Lesson Learned 9
Course of events
A main engine of 8000 KW // 142 rpm with approx. 80.000running hours. The vessel had passed a special survey the yearbefore and was taken over by the new owners a few monthsbefore the main engine was damaged.
The vessel was trading world wide and an ingress of water to themain engine lube oil was discovered shortly before arrival in a port.Upon arrival the main engine crank case was inspected withoutany visible signs of leakage and the lub.oil was changed.
A few hours after leaving the port there was a pressure drop inthe main engines lub.oil system. This was adjusted by setting theby-pass valve and the pressure difference at the lub oil filter wasequalised by back flushing.
A new pressure drop in the lub.oil system was encountered afteranother 30 min and the engine was stopped and filters wereinspected and cleaned. The magnet plugs in the filters were foundwith metal dust. The engine was restar ted and it was decidedto return to port with reduced power for further investigation.During this return tr ip some pressure drops were encounteredand the filters were cleaned with back flush every 30 minutes inattemts to control the pressure.
Extent of damage
The engine crank shaft had sustained severe damage to bearingjournals. Pistons and cylinder liners were also damaged. The mainengine had to be dismantled and various parts to be renewed.
The work took abt. 120 days, which also included some of the
owners maintenance work.
Causal connections
The subsequent investigation revealed that the water ingress camefrom the piston cooling system. Further on the single lube. oil
separator was working with reduced capacity. The significant watercontent in the lub.oil probably caused the pressure drop and poorlubrication of the engine which caused the damages to the bearingjournals and cylinders.
Despite several pressure drops etc. during the return trip, the
vessel continued to keep the main engine running instead ofrequiring a tug boat for assistance.
Lessons to be learned
There are two sides of every casualty, loss prevention and lossmitigation. On the loss prevention side the causal connectionswater in main engine represent the immediate cause behind thedamages.
The lack of regular inspection/maintenance, which is a part of anormal Programmed Maintenance Scheme (PMS) contributedto the break down. If a PMS had been implemented, appropriateactions most likely would have been initiated in order to rectify thefaults at an earlier state.
On the loss mitigation side there is the decision to continue tooperate the main engine, which resulted in an excessive load andfurther damage. This load and ingress of water to the crank casewas more than the engine was capable to handle. This combinedwith only partial lubrication of the cylinders resulted in the severedamages to the main engine.
The immediate cause behind the water ingress to the M.E. lube oilwas a leaking piston cooling system. The reduced capacity of thelube oil separator could not handle the leakage properly.
The basic cause behind the water ingress was the lack ofproper maintenance. A proper Planned Maintenance System isrecommended.
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8/10/2019 LL09 Main Engine Damage A4
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MAIN ENGINE DAMAGE Toolbox of Knowledge: Lesson Learned 9
Prevent Detect Control MitigateDetect ControlAccidentalEvent
Design, construction
and maintenance.
Monitoring of
operation values.
Water in theM.E. lube oil and
frequent pressure
drops.
Filter cleaning by
back flush. Reduced
power. Return toport.
The damaged journals
were detected when
the ship was back inport.
Loss of Propulsion
Damage to bearning journals.
The first lesson to be learned is that active usage of a proper
Planned Maintenance System (PMS) is important to minimise
the likelihood of damage to any machinery parts.
The second lesson to be learned is that if alarms are
encountered they shouldnt be overridden unless it is a matter
of a critical emergency to proceed.
Finally it is important that the management continually evaluates
the operation and incoorporates adequate systems to promote
performance.
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and Sweden. If you like to contact our marine insurance experts please call or
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