A newly-released WorkSafe report into a bus crash that killed three people in 2016 showed investigators identified weaknesses in the bus firm's maintenance systems.
The bus hired from Ritchies Transport had been carrying 53 people from Tonga's Mailefihi Siu'ilikutapu College brass band when it plunged down a bank near Gisborne on Christmas Eve 2016.
Ritchies Transport rejects the WorkSafe findings and says the Crown agency's investigator had no mechanical or workshop experience.
WorkSafe stands by the investigation - even though it shelved the maintenance allegations before they got to court and Ritchies this year pleaded guilty to a single charge relating to how it hired out buses.
This is the first time the WorkSafe report and related documents have been released.
They record the aftermath of the crash when the brakes of the bus failed on a steep hill.
The documents, released to to RNZ under the Official Information Act, include reports from two external investigators who inspected the crashed bus. Each said the bus showed signs of not being properly maintained.
But doubt was cast on that by an investigator for Ritchies' defence, who reviewed the case 18 months after the crash.
Ultimately, WorkSafe agreed in a summary of facts that Ritchies had documentation relating to maintenance and inspections of its fleet generally, and a planned maintenance programme.
The WorkSafe investigation focused on the wider fleet maintenance programme run by the company, which operates 1200 buses nationwide.
The investigation detailed checks and interviews done at the Auckland depot the bus had left from.
- A week before the crash, a driver on a school trip using the bus that crashed, found the brakes were "soft and spongy"; she said she told Ritchies mechanics
- The day before the crash, another driver had problems "consistent with the rear brakes not working effectively"; he said he told a Ritchies supervisor
- Ritchies was draining the airbrake systems on buses every 5000km, though manufacturer Nissan gave instructions to drain them every day
- Ritchies provided no standard operating procedure for inspecting, servicing or adjusting brakes
- Drivers reported not having enough time to do a comprehensive pre-start check
- The daily check system "did not cover what it needed to cover to keep the buses in a safe condition and ... was not effectively communicated, implemented or monitored"
- The design and use of a servicing checklist by Ritchies' mechanics "meant that the likelihood of human error ... was high"
- There was a high number of mechanics who were not fully qualified
- Only two of the nine mechanics who worked on bus in the year before the crash had full New Zealand qualifications
Ritchie's response to findings
The transport company rejected the findings and defended its maintenance record.
"The WorkSafe investigation was carried out by a health and safety inspector with no mechanical background or any experience in a workshop," director Andrew Ritchie said in a statement.
"WorkSafe lacked the confidence of these findings in the report and so did not take them to trial."
As at last December, Ritchie was pleading not guilty, and had challenged the admissability of WorkSafe's investigation in court.
WorkSafe shelved the report and in April 2019 the company pleaded guilty to an amended charge laid by the Crown agency of failing to ensure the health and safety of other people was not put at risk. This focused on its hireage of buses. The company was sentenced in September.
Without the maintenance allegations, the judge at the sentencing said there was "no evidence" to suggest the crashed bus had any pre-existing brake problem.
She also said Ritchies had an exemplary record, with no prior convictions for health and safety offending.
WorkSafe defends investigation
WorkSafe head of specialist interventions Simon Humphries said its investigation was professional in every respect.
"It met WorkSafe's internal standards. We stand by the investigation and its final outcome in court," Mr Humphries said in a statement.
Two external experts brought in by the Crown agency inspected the bus and their two reports - also released under the OIA - said there were signs some brake faults were pre-existing. They also registered concerns about wider maintenance at Ritchies.
WorkSafe said the findings were used to inform its other inspectors and vehicles programme, and were passed to the Transport Agency (NZTA).
WorkSafe sent Ritchies an improvement notice in August 2017 to ensure it did daily airbrake draining.
NZTA audited six Ritchies depots in June 2018 - 18 months after the crash - and found they "overall showed a high level of compliance".
It remains unclear why WorkSafe amended the charge to focus in on flaws in Ritchies' system for hiring out buses.
The agency said this was due to new information that came up.
Ritchies said this related to its expert report in May 2018 - and a peer review of the investigations - that it said undermined the findings both about the crashed bus and the maintenance programme.
The report author, Dr Tim Stevenson, told RNZ the report did not go into Ritchies' wider maintenance programme but focused only on the crashed bus.
He said it was not possible to state categorically whether the brakes were in correct working order or not before the bus left the depot.
WorkSafe told RNZ of its report on the depot investigation, that it "does not reflect the facts that were subsequently established and the failures that Ritchies pleaded guilty to".