• HMAS Adelaide sits alongside Nuku'alofa. (Defence)
    HMAS Adelaide sits alongside Nuku'alofa. (Defence)

Defence’s 2 March announcement that HMAS Adelaide had been succeeded in command of the ADF Joint Task Group for Operation Tonga Assist 2022 by sister ship HMAS Canberra spelt the conclusion of what will have been a seven-week deployment impacted by equipment issues. Adelaide left Brisbane for Tonga on 20 January and will return to Sydney on 11 March.

Questions about a major electrical power failure that stranded the 27,000-tonne Landing Helicopter Dock (LHD) in Tonga after delivering humanitarian supplies following the 14 January volcanic eruption and tsunami were finally answered in Senate Estimates on 17 February – nearly three weeks later.

In fact there were two separate power failures on successive days, details of which were disclosed in Estimates on 17 February after a dearth of official information regarding Adelaide’s status and her whereabouts.

The LHD arrived in Tonga on 26 January and the same day completed a contactless unload of 88 tonnes of supplies onto Vanu Wharf in Nuku’alofa, according to a 31 January Defence press release.

The release stated that the ship was awaiting further requests from the government of Tonga - notwithstanding an earlier statement by the country’s Health Minister, Saia Piukala, that Adelaide would leave immediately after delivering the supplies.

However, later that day the ABC disclosed that Adelaide had suffered a major electrical power outage.

A subsequent Defence statement confirmed that Adelaide had experienced a power failure. Backup power had been activated, essential functions such as refrigeration and sanitation systems were up and running, food supplies had not been adversely affected, and civilian specialists were on their way to Tonga to assess the affected systems.

However, from 2 to 14 February, Defence failed to respond to questions on Adelaide’s status and whereabouts, nor on whether precautionary equipment checks were being undertaken on sister ship Canberra.

On 15 February Defence’s news website reported on Adelaide being replenished at sea “in Tongan waters,” by HMAS Supply.
And on 17 February, Chief of Navy Mike Noonan told an Estimates hearing that Adelaide had experienced a total power failure while at anchor on 29 January when the online diesel generator failed.

The reason for the failure was part of a wider technical investigation that was underway, he said, noting that emergency power was restored within a matter of hours.

The following day Adelaide suffered a second power failure, this time from a gas turbine. Emergency power was restored within two minutes, full power was restored during the course of the day, and the ship was back to full operational capability on 31 January, Vice Admiral Noonan stated.

“It was not a single point of failure, as we might have opined”, he said.

“It is a complex operating environment with the ash-laden air and water that the ship was operating in, which led to increased temperatures in some of the systems in the ship, which may have contributed to the power failure, but I’m not in a position yet to offer a conclusive cause for that failure.”

Rear Admiral Wendy Malcolm, head of Maritime Systems at CASG, subsequently disclosed that a second diesel generator brought online had also overheated and shut down. In this case however, a sensor defect was suspected where the generator thought it was overspeeding.

The ship’s company had been able to restore power itself. Contractors that arrived later were able to take ‘quite a bit’ of information from the integrated platform management system to understand exactly what had happened, RADM Malcolm said.

Both LHDs were sporadically either unavailable for service or subject to operating restrictions during 2017 due to irregularities within their azimuth propulsion pod systems.

These problems were later linked to the migration of oils across seals in the propulsion systems.

Each ship is propelled by two Siemens Navantia 11-megawatt azimuth thrusters, each with an onboard electric motor driving 4.5 metre thrust propellors. The electricity is provided by a combined diesel and gas (CODAG) system.

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