MO-2017-203

On 9 February 2017, the crew of the Bermuda-flagged passenger ship Emerald Princess were conducting maintenance on one of the lifeboat launching systems while the ship was berthed at Port Chalmers, Dunedin.

The maintenance was completed and the crew were restoring pressure to a bank of high-pressure nitrogen-gas cylinders that formed part of the launching davit ‘stored energy’ system. One of the nitrogen bottles burst, fatally injuring a crew member who was standing close by.

The Transport Accident Investigation Commission (Commission) found that the nitrogen cylinder burst at below its normal working pressure because severe external corrosion had reduced the wall thickness to about 30% of its original thickness.

The failed nitrogen cylinder and several other pressure cylinders within the stored energy system, despite having been surveyed about two weeks earlier, were not fit for purpose and should not have been left in service.

The Commission also found that there is an urgent need for consistent and proper standards to be developed at a global level for maintaining, inspecting, testing and, where necessary, replacing high-pressure cylinders associated with stored energy systems on board ships.

The operator took a number of immediate safety actions to prevent a recurrence of the accident on any of its ships.

The Commission issued an interim report with early recommendations to the equipment manufacturer, the International Society of Classification Societies, the Cruise Lines International Association and Maritime New Zealand to alert their members and surveyors as appropriate to the circumstances of the accident and to have the condition of similar installations checked.

The Commission made two additional recommendations: one for the manufacturer to improve training for its surveyors; and one for Maritime New Zealand to raise, through the appropriate International Maritime Organization safety committee for its consideration, the implications for maritime safety of not having adequate minimum standards for the inspection, testing and rejection of pressure vessels that are part of stored energy systems.

A key lesson arising from this inquiry is:
- any sign of corrosion on high-pressure cylinders should be fully investigated by a person competent in examining high-pressure cylinders before any remedial work is undertaken and the cylinders are allowed back into service.