Allan Allarde Navales (32), a father of two, was standing close to the cylinder when it burst on board Emerald Princess on February 9, while the ship was docked in Port Chalmers.
Mr Navales was fatally injured when the cylinder burst, an interim report released yesterday by the Transport Accident Investigation Commission said.
Corrosion had reduced the thickness of the cylinder wall by 75% to only 1.5mm at the point of failure.
The cylinder, which was one of four used to pneumatically launch one of the ship’s lifeboats, exploded with such force the top of it was never found. Crew members were refilling the cylinders, as the pressure in the system had dropped below its working range.
They checked the system for leaks but did not find any, the report said.
"They did not check the nitrogen cylinders because they thought it highly unlikely that the pressurised cylinders had been structurally compromised."
They decided to replace the pneumatic system’s manifold.
It was while refilling the system after the manifold’s replacement that the cylinder exploded.
"The metallurgist’s initial assessment was that the failure had occurred as a result of overload caused by corrosion thinning," the report said.
"A number of other cylinders on board the ship were observed to have similar corrosion-related damage."
The cylinders were inspected only two weeks before the incident and found to be in a satisfactory working condition.
The manufacturer of the system told the commission it had reported the cylinders were aged and recommended replacing them, even though the system was in working order.
A Princess Cruises spokesman said the company had reviewed the interim report.
"The maintenance was being conducted in line with established protocols for inspections and maintenance of cylinders as recommended by the manufacturer,’’ he said.
"The loss of a crew member is a terrible tragedy for our company and we continue to assist the crew member’s family.
"In addition to actively assisting the commission in its inquiries, Princess Cruises took immediate action in replacing all of the cylinders used in the ship’s lifeboat launch and recovery system, inspecting similar cylinders across the line’s global fleet and updating maintenance and training programmes."
TAIC chief investigator of accidents Captain Tim Burfoot said while the interim report had been released, the investigating was ongoing.
The commission could make recommendations, but could not pursue regulatory or criminal matters.
A separate investigation by Maritime New Zealand was assessing the regulatory aspect of the incident.
A Maritime New Zealand spokesman said that investigation was also ongoing.
"As to whether further action might be taken ... those decisions haven’t been made yet," he said.
He did not want to speculate on when that investigation might be concluded.
