Engineers make mistakes. Although we like to consider ourselves on a higher plane than other mere mortals, there are times when we get it wrong. But having learnt from our mistake, or better still, other engineers' mistakes, we move on, wiser and more knowledgeable than before.
However this catalogue of errors which ended with a crankcase explosion are so incredible that you will probably join me in thinking that those responsible could not call themselves engineers.
The engine involved was an MAN B&W L58/64 which is a large powerful medium speed 4 stroke engine. The Lubricating Oil was supplied by an engine driven pump and is filtered through a set of fine mesh filters and a set of backflushing candle filters.
On this vessel the automatic backflushing for the LO filters was not working. (from what follows I doubt whether those on board would have the knowledge on how to fix the fault). The frequency at which they were having to manually backflush the filters was increasing to a point that the poor lambs were not able to get a decent nights sleep when running UMS. So they bypassed the filters.
The engine LO pressure was beginning to fall which of course activated the Low LO pressure alarm. What an inconvenience! So they bypassed it. Meanwhile they also removed the fine mesh LO filters in case this was the cause of the Low LO pressure. They were now getting oil mist detector alarms which was a dog of an nuisance. So..... yes, they bypassed that alarm.
By now the LO pressure was so low that the shut down was operating and they couldn't start the engine.... Soon fix that!!....
When the engine was restarted a crankcase explosion occurred.
So what had happened? Well when the cavalry arrived, the men working below (I cant call them engineers) weren't exactly the most truthful. But they were so stupid that they didn't realise that the onboard computer system logged all the alarms and so after a bit of investigation it wasn't hard to work out the sequence of events.
On opening up the LO pump, it was found to have virtually disintegrated.
One crankpin was so severely damaged that 17mm had to be ground off: taking it to just above the limit where the engine would have had to be de-rated.
All bearings (main, thrust, bottom and top end, camshaft, and Turbocharger had to be replaced.
Piston Pin Socket in Piston
Pistons and liners had to be replaced as were the engine room staff.
It was later found that they had filled the thermal oil system up with water....but that's another story!