Fatal crankcase explosion A superintendent has been killed by a crankcase explosion in a MAN B&W low-speed engine on a Korean test bed. The accident happened when a bearing in the chaincase overheated, causing a build-up of oil mist while the engine was undergoing shoptrials.
The Motor Ship understands that the oil mist detectors were not wired into the test bed's alarm system. Following the incident MAN B&W has re-issued advice on the testing procedure, stressing that oil mist detectors must be connected before the initial start-up.
It has also upgraded the instruction saying that with immediate effect the oil mist detectors must be connected to the automatic shut down system on the testbed rather than to the alarm system. "If anything is going to go wrong it is most likely to happen in the shop trial - that's why the trial is run," says Mr. Jakobsen, manager of new design at MAN B&W.
Wärtsilä NSD has not issued specific instructions on the connection of oil mist detectors during shoptrials, saying it expects its licensees to take all precautions to protect its workers. However, it is reviewing this policy in the light of this accident.
Christian Lutsen of AP Moller, whose Sovereign Maersk suffered a crankcase explosion, says he feels it would be smart to have a thicker white metal layer in the bearings. In the event of a main bearing failing, as happened in the 12K90 engine aboard Sovereign Maersk, there would not be metal-to-metal contact.
Mr. Jakobsen from MAN B&W says the company would not revert to thicker bearings as this would lower the load carrying capabilities and not solve the problem. If the failed bearing had a thicker layer then it would wear down the neighbouring bearings, and within a few hours the same metal-to-metal contact occur, he argues.

Left to right: large, small and no shield - demostrates why MAN B&W does not recommend shields on crankcase valves.