• HMAS Hobart berths alongside her sister ship HMAS Brisbane at Fleet Base East.
    HMAS Hobart berths alongside her sister ship HMAS Brisbane at Fleet Base East. Defence

Long-planned modifications are underway on HMAS Hobart to improve the storage of Mk54 torpedoes and AGM-114N Hellfire missiles for the Air Warfare Destroyer’s MH-60R naval combat helicopter.

To avoid construction delays, these modifications were held over until the ship’s first scheduled maintenance period, now underway at Sydney’s Garden Island.

Commodore Steve Tiffen, CASG’s Director General Naval Construction Branch, told ADM the same modifications would be completed on NUSHIP Sydney, probably at Osborne, before delivery in the first quarter of 2020, and on second-of-type HMAS Brisbane in the near future.

Other work will involve changing the external lighting systems, in particular the flight deck lights, to be more compatible with night vision devices.

Prior to the changes now underway, HMAS Hobart has been able to deploy with the MH-60R together with Mk54s and Hellfires, but not with the full combat load.

The magazines of the Hobart-class AWDs were originally designed for the Mk 46 torpedo but were modified during construction to accommodate the ship-launched Eurotorp MU90.  The Hellfire AGM-114N air to surface missile is also a new weapon for Navy although the AGM-114M – the same missile but with a blast fragmentation rather than a metal-augmented thermobaric warhead – was already in service with Army’s Tiger armed reconnaissance helicopters.

The modifications include racks for Hellfire and Mk54 storage and the installation of blowout doors for the magazine.

While the MU-90 torpedo is battery powered, the Mk54 is powered by liquid Otto Fuel II, a toxic combination of propylene glycol dinitrate, nitrodiphenylamine, and dibutyl sebacate.

The modifications include an Otto fuel detector being fully integrated into the ships’ management systems and Otto fuel spill kits properly integrated into the magazine.

In comparison with the MU90 the Mk54 is about one and a half inches shorter and some 50Lb lighter. However, flight-in-air material adds to the overall length of the Mk54 by about eight inches.

Additional magazine space will enable flight-in-air material such as the suspension bands that attach the weapon to the MH-60R, the drogue parachute that decelerates the torpedo after launch and positions it at the right angle entering the water, and a frangible nose cap protecting the face of the sonar transducer that separates on water entry, to be fitted to the Mk54 in the magazine rather than the hangar.

Work on NUSHIP Sydney is now about 95 per cent complete, and a number of interior compartments are being certified as complete and locked until sea trials begin in the last quarter of this year.

Arrival in Sydney is scheduled for the first quarter 2020, with the ship likely to be handed over from CASG to the RAN towards the end of that period and commissioning expected to take place early in the second quarter.

Defence Minister Christopher Pyne has announced a six-year $40 million limited tender by which Raytheon, the combat systems integrator for the Hobart-class AWDs, will act as Defence’s agent in ensuring Lockheed Martin and Saab’s work in integrating the combat systems of the Hunter-class frigates “is second to none in the world.”

Pyne said Defence did not want to lose the capabilities created by Raytheon over the AWD program.

“It’s also important for the Department of Defence to have its own independent agency, its own independent capability, to ensure that our interests are being absolutely protected,” he added.

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