The Australian Defence Force failed to replace helicopter engine blades prior to a crash near Jervis Bay last year despite longstanding advice from the manufacturer to do so, an investigation has found.
A report tabled in the Senate reveals the findings of an investigation into the March 2023 incident in which the crew of an MRH-90 Taipan helicopter escaped with only minor injuries.
The Jervis Bay incident happened four months before the fatal crash of another MRH-90 helicopter off Queensland’s Whitsunday Islands. Four servicemen died in the July 2023 incident and the government decided to retire the ADF’s entire MRH-90 fleet early.
The defence minister, Richard Marles, confirmed in a letter tabled in the Senate that the internal investigation into the earlier Jervis Bay incident was now complete.
But he said Defence had advised him that “there is a significant risk that release of the full report and associated documents at this time may influence the willingness of personnel to participate in other investigations, which may impede ongoing investigations into the incident of Lindeman Island on 28 July 2023”.
“In the interests of transparency, Defence has provided a redacted version of the Defence Flight Safety Bureau Executive Summary of the Aviation Safety Investigation Report that is suitable for public release,” Marles wrote.
The report – also tabled in the Senate – said the failure of an HP1 blade caused “the catastrophic, but contained, engine failure” in the Jervis Bay incident.
It said while this incident “was the first of this type” experienced by an ADF MRH-90 Taipan, the manufacturer had issued a service bulletin in 2017 “as a result of several HP1 failures across the global fleet”.
At the time, the manufacturer recommended that operators of the RTM-322 engine should replace HP1 blades with modified blades.
But the report said officials had “determined that the ‘Design Safety Case’ for the MRH-90’s RTM-322 engine remained within the certification basis albeit with an extremely small increase in the likelihood of engine failures throughout the life-of-type of the MRH-90 fleet of aircraft”.
Officials had decided to modify the engines as per the manufacturer’s recommendations “during routine deeper-level maintenance programs”.
Consequently, the engines of the helicopter involved in the Jervis Bay incident had not been fitted with new HP1 blades, the report said.
The same report said the flying pilot’s decision to shut down the right-hand engine “was not in accordance with standard emergency procedures”.
The investigation found “the crew were more than likely not experiencing acute fatigue on the day of the mission”.
“However, evidence suggests 6th Aviation Regiment’s tempo of operations and workload on key executives, supervisors and managers created the pre-conditions for cumulative fatigue,” the report said.
The One Nation senator Malcolm Roberts told the Senate the report “demonstrates Defence was willing to overlook serious risks when it came to this helicopter”.
Roberts told the Senate: “How many other problems with the MRH-90 helicopter did Defence overlook?”
A Defence spokesperson told Guardian Australia the department was “committed to supporting the multiple investigations and inquiries” into the Lindeman Island incident.
As part of efforts to support the families of the soldiers killed in the July 2023 crash, the spokesperson said Defence “briefed [them] on key details of the interim technical report and the update to the preliminary report within the boundaries of the active safety investigation.
“Providing a running commentary on the inquiries is not helpful or appropriate surrounding the cause of the incident and is harmful and deeply upsetting for all involved.”
• This article was amended on 17 September 2024 to clarify an engine blade needed to be replaced, not just a blade.
