Crew cleaning a boiler that hadn't cooled caused an explosion on a ship berthed in Bluff back on 24 May 2025, that injured three people, the Transport Accident Investigation Commission has found.
The commission released its final report on Friday into the accident on board the Malta-flagged M.V. Olivia, which occurred in May last year. Two crew members received serious burns and the third received bruising. All three were taken to Kew Hospital in Invercargill.
The crew were cleaning the boiler by air blasting soot from inside it when a blowback explosion occurred.
"It is likely that the boiler initially flamed out and failed to restart because of a combination of the following issues. Malfunction of the burner's air-intake flap, the faulty ignition transformer and buildup of soot inside the boiler," the report said.
The Olivia had arrived in Bluff a month before the accident, with the port stay originally scheduled for five days. Urgent maintenance and repair work on all the ship's generators extended the stay indefinitely.
The commission said the crew considered boiler cleaning a routine activity, normally done a few days before arriving at port.
"Although the activity was familiar, the conditions were not. Cleaning the boiler at sea, after it had cooled for several days, differed materially from cleaning it after repeated ignition attempts and an earlier blowback while the furnace remained hot," the report said.
Chief investigator of accidents Louise Cook said it was likely that disturbed heated soot ignited residual fuel as the air lance was withdrawn.
"Before internal cleaning, a boiler furnace needs to be isolated and verified as safely cooled. Blowing compressed air into that hot furnace with unburned fuel was a recipe for a blowback," she said.
The investigation identified two safety issues: inadequate implementation of the vessel's safety management system, and a lack of guidance for managing crew during sustained intensive work periods.
The report said it was "very likely" that senior engineering officers were fatigued as they worked to complete the generator repairs, and that this adversely affected their decision-making. There were also no senior engineering officers on duty overnight, meaning no one authorised to oversee work carrying higher risk than what was planned for the night shift.
TAIC said it was very likely the severity of the injuries would have been reduced if crew members had worn appropriate face protection.
"The decision to not use any face or eye protection was further indication that the crew did not appreciate the risk," the report said.
"Long repair programmes need continuing attention to workloads, rest and supervision. If an unexpected job is beyond people's capability, it should be a straightforward decision to stop and get the right support," Cook said.
The ship's operator, Fleet Management Limited, had taken several steps to address both issues, including reviewing procedures, protective equipment and fleet training. As a result, the commission did not issue any new recommendations.