A new report has revealed a piece of safety-critical equipment that was 13 years older than it should have been, failed and caused the Interislander ferry Kaitaki to lose power in the middle of the Cook Strait.

The Transport Accident Inquiry Commission (TAIC) revealed in a preliminary report that when the ship lost power due to a generator trip on January 28, a rubber expansion joint (REJ) which was too old ruptured, flooding the engine room bilge system with water from the ships high-temperature water cooling system.

The loss of water pressure from the cooling system meant the engines could not be restarted safely, and propulsion could not be restored “in a timely manner”.

As a result, the ship drifted in the Cook Strait for an hour with 864 people on board.

TAIC revealed that the REJ that ruptured had been installed when it was 13 years old, had been in service on board the ship for five years, and it was 18 years since it was manufactured.

A comparison of a serviceable REJ (left) next to the one which ruptured on board the Kaitaki. Photo / Azaria Howell

It should have been no older than eight months from its manufacture date when it was installed, according to its manufacturer, and should have been replaced within five years.

It was two months overdue for replacement when it failed.

KiwiRail advised the Commission it has introduced a rule that REJs are stored for a maximum of four years, and can be in use for a further four.

On top of this, KiwiRail has replaced all the REJs onboard the Kaitaki, and assessed the condition of all the other REJs in the fleet - but although TAIC welcomes this, it says it is not enough.

“The Commission is concerned that there remain REJs in operation in the KiwiRail Interislander fleet that do not meet manufacturers guidance and are at increased risk of failure.”

KiwiRail’s chief executive Peter Reidy has apologised for the failure, and said the organisation is committed to ensuring nothing like it happens again.

“This was a serious event, and we are deeply sorry for any distress it caused to our passengers and crew,” Peter Reidy says.

“Since the incident we’ve inspected all rubber joints across the entire fleet and replaced all safety critical rubber expansion joints on Kaitaki and the rest of the fleet, as a precautionary measure.”

“Our message to passengers, staff and customers is clear: Our ships are safe and we are closely monitoring all the safety critical equipment on our vessels.”

TAIC has recommended that Maritime New Zealand require evidence from KiwiRail that all REJs onboard its ships are fit for purpose, no older than eight months from the date of manufacture and are inspected annually.

On top of this, the safety-critical seals must be replaced every five years, regardless of the findings of the annual inspection.

Jane Meares the chief commissioner of TAIC said the incident was “certainly a failure of maintenance in regard to the safety critical components”.

The Transport Accident Commission (TAIC) released the findings this morning after announcing earlier in the week it was so urgent it could not wait until the conclusion of the full investigation which could take up to 18 months or even longer.

TAIC opens an inquiry such as this when it believes the circumstances of an accident or incident have, or are likely to have, significant implications for transport safety. It is one of three investigations into the incident - the other is being held by Maritime New Zealand alongside an audit of Interislander and it’s ferries and the third is being conducted internally by KiwiRail.