Problems that led to an Australian navy ship losing power twice while providing aid to Tonga may have been caused by volcanic ash, defence officials have revealed.

HMAS Adelaide had a total power failure on 29 January while anchored in Tonga after delivering 88 tonnes of aid.

Emergency power was restored within a matter of hours but a second power failure occurred a day later.

The first failure was said to be a result of the diesel generator failing and the second because of a gas turbine. A wider technical investigation is underway.

The head of maritime systems at the defence department said the ash in the air and water after the volcanic eruption could have affected the ship’s seawater cooling system.

Rear Admiral Wendy Malcolm said the navy had never sailed into such an environment involving a volcanic eruption.

“We believe and we think it’s quite possible that it’s a key factor in the generators going down,” she told a Senate estimates hearing.

“The seawater cooling became blocked because of the ash and the rock in the water and that has caused the seawater cooling to overheat which has caused the diesel generations to go into shutdown”

A sensor defect with the emergency diesel generation where the generator thought it was over-speeding subsequently followed, she said.

“It is a series of events where the holes in the Swiss cheese have lined up,” Rear Admiral Malcolm said.

Chief of Navy Michael Noonan said the exact nature of the faults remain part of an ongoing investigation but confirmed the faults didn’t come down to a single point.

“We have not seen another electrical failure in the HMAS Adelaide and confidence by the commanding officer and the technical staff in the electric propulsion system is high,” the vice admiral said.

“She is fully mission capable; she continues to deliver support as requested by the Tongan government.”

The HMAS Adelaide, which has been stationed for three weeks, remains fully operational and will remain in Tonga until it is replaced by the HMAS Canberra.

The revelation came just hours after the federal government’s $45 billion (US$32 billion) frigate programme came under the scrutiny of senators.

Independent senator and former submariner Rex Patrick pushed officials on an internal engineering report that raised concerns the ships would be slower, louder and have a shorter range than first thought.

The national navy shipbuilding deputy secretary said the ships’ specific performance requirements are yet to be determined but noted further delays and problems would cause the project to be listed as a project of concern.

“If we were to experience further delay we would absolutely be looking at discussing with government about adding this project to the projects of concern list,” Tony Dalton told senators.