The Kaitaki in the Marlborough Sounds. Photo: Supplied / KiwiRail
Safety checks on ferries following an hour adrift for 800 people in Cook Strait, found hundreds of components were more critical than thought.
KiwiRail checked its whole fleet after an old cooling system joint blew out on the Kaitaki in January, leaving it powerless and drifting towards rocks.
A report released under the Official Information Act shows 10,000 components were checked on four ferries afterwards.
This led to 369 components being newly tagged as critical.
Fleetwide, 258 work orders that had previously been considered non-critical, were elevated to critical.
Overall, after the checks, 754 orders for work on critical components were lodged.
Most of the critical work was within its due date, "highlighting that the underlying asset management system was working effectively", KiwiRail's report said.
Its focus had been on the vessels' cooling systems.
The report said "identification of any overdue/deferred maintenance activity on critical equipment list" was done, but did not give many details.
RNZ asked KiwiRail for details months ago of its fleetwide safety checks, but it provided them only for the Kaitaki, not the others, saying this was too much work. It released the 10-page fleet checks report from 27 February instead.
The report sketched the changes made since January to how components were assessed to see if they were critical, which included their track record: "Looking at key operational input from frontline staff towards their experience with equipment."
The 10,000 components were shared out: 3335 on the Kaitaki; 2484 on the Valentine; 2386 on the Kaiarahi; 1865 on the Aratere.
A preliminary investigation report was rushed out mid-year to warn ship operators that old joints could be dangerous.
However, KiwiRail has continued to dispute the Transport Accident Investigation Commission's accusations that it breached manufacturers' guidance on how long the joints could last.
An earlier OIA showed the Kaitaki had several joints as old as the one that blew in January.