BEA mer report , Pont Aven, engine room fire casualty investigation

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After leaving Plymouth on the afternoon of Sunday 28 April 2019, the ro-ro passenger vessel PONT-AVEN was sailing to Santander in favourable weather conditions. During the night, while in the south of Pointe de Penmarc’h, a strong vibration was felt in the vessel.

An automatic safety device stopped one of the four main engines. The breakage of a part, at the level of a connecting rod small-end of the main engine n°2, caused very important mechanical damages, leading to the tearing off of some of the crankcase doors of this engine. Very high-temperature oil mist escaped from it and then ignited, causing a fire to break out in the engine room. Fire detection triggered the alarm and activated the automatic operation of the fixed water mist extinguishing system. The use of several teams of firefighters from the crew enabled the fire to be brought under control. There were no casualties from the accident.

During firefighting, passengers were called to assembly stations for safety reasons. Everything went smoothly.

As the vessel was still manoeuvring, the decision was taken by the shipping company to divert to Brest. An evaluation and response team, dispatched by the Préfecture maritime de l'Atlantique, had been hoisted aboard and took part in the safety patrols organised during the transit. The intervention, assistance, and salvage tug ABEILLE BOURBON escorted PONT-AVEN to Brest where the passengers were disembarked.

Conclusions

A mechanical failure caused the crankcase doors to burst open, the release of hot oil vapour caused a fire in the engine room.

The safety shutdown of the ME2 and the automatic triggering of the Hi-Fog were decisive in limiting the consequences of the accident.

In the context of fire management, the crews' ability to intervene was remarkable.

The cause of the accident is most likely due to cracks either in the connecting rod small-end or in the piston pin of the ME2 A5 cylinder. Due to cracks detected in the piston pin as a result of inclusions in the metal during manufacture, a first hypothesis would be a seizure of the piston pin in its housing to explain the separation of the connecting rod and the piston.

However, the cracks of the piston pins observed in the past by the engine manufacturer on vessels of other shipowners than BAI had not caused any proven accidents. A second hypothesis would be a crack in the connecting rod small-end as the primary cause of the failure, given the history of this part.

As a precautionary measure, the company decided to have all piston pins of the main engines of PONT AVEN replaced.

The original piston pins from 2003 were checked during their manufacture according to the calibration determined at the time. The engine manufacturer does not see any technical interest in imposing a replacement periodicity for the piston pins as they are not considered as wear parts.

The BEAmer notes that major maintenance work on the main engines was not the subject of sufficiently detailed reports that would make it possible to keep written records of the scrupulous follow-up of the engine manufacturer's recommendations

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