Preliminary report - maintenance for safety critical rubber expansion joints

4 May 2023
the ruptured rubber expansion joint
The ruptured rubber expansion joint. TAIC photo

The Transport Accident Investigation Commission (TAIC) has called on Maritime New Zealand to address critical safety issues with the maintenance and management of ship engine cooling systems.

The call is detailed today in a preliminary report as part of the Commission's inquiry into the loss of power experienced by the KiwiRail Interislander passenger ferry Kaitaki, leaving it drifting close to the coast in Cook Strait on the night of 28 January 2023.

The Chief Investigator of Accidents, Naveen Kozhuppakalam, says TAIC has recommended that Maritime New Zealand require KiwiRail to provide evidence that safety-critical rubber expansion joints on the Interislander fleet are fit for purpose taking into account the manufacturer’s guidance; and alert operators of ships that have these components that maintenance schedules should account for date of manufacture as well as time in service.

"The crew were conducting maintenance on the propeller shaft generator when it tripped and the vessel lost all electrical and propulsive power," said Mr Kozhuppakalam. 

"The main and auxiliary engines shut down because their high temperature cooling water system had failed; this happened in part because one component, a rubber expansion joint, had ruptured and most of the cooling water drained out before the crew could stop it." 

It took the crew about an hour to repair the cooling system and re-start the engines. 

The rigid pipes of the Kaitaki's engine cooling system included twelve rubber expansion joints (REJs) to reduce vibration and noise; compensate for heat expansion, load stress and pumping surges; allow for misalignment of pipes; and can make inspections easier.

These REJs are safety-critical components that should been tracked and checked throughout their lives. This is because, over time, as is common with manufactured rubber components, REJs become more susceptible to cracking, delamination, and can become softer or 'gummy'. 

"They should be taken out of service before their natural ageing process puts them at unacceptable risk of failure. Ship operators need to follow the manufacturer's instructions, which say the REJs they should be no older than eight months when installed, inspected annually and replaced after five years. 

"Kaitaki's ruptured REJ was thirteen years old when installed in 2018 and eighteen years old by the time it ruptured.

"This happened because KiwiRail had not followed the manufacturer's advice; even under KiwiRail's own system, the REJ was two months overdue for replacement.

Since the incident, KiwiRail has updated its guidance for REJs, but it still doesn’t comply with the manufacturer’s guidance and doesn't account for the date of manufacture.

TAIC's inquiry into the Kaitaki incident is continuing, with current lines of inquiry that include maintenance, safety systems, emergency response and emergency capability. A final report, setting out findings, safety issues and recommendations, if any, will be issued at the completion of this inquiry.