Volcanic debris around Tonga is considered the likely cause of an initial power outage that crippled Australia's largest warship HMAS Adelaide at the end of last month.
Last month, the ABC revealed the navy's landing helicopter dock was left temporarily without any power supply while completing its humanitarian operation after the January volcanic explosion and subsequent tsunami waves.
At a senate estimates hearing, naval officials have been questioned by Independent Senator Rex Patrick about the incident, which remains under investigation.
Rear Admiral Wendy Malcolm told the committee it was likely polluted seawater blocked the ship's diesel generators, forcing them to overheat and shut down.
"We have never sailed into an environment that's been subject to a volcanic eruption like this, and we believe, and we think, it's quite possible that it's a key factor in the generators going down," Rear Admiral Malcolm said.
"The seawater cooling [system] became blocked because of the ash and the rock in the water and that has caused the seawater cooling system to overheat, which has caused the diesel generators to go into shutdown [mode]."
The Chief of Navy, Vice Admiral Mike Noonan, also revealed multiple system failures contributed to the first total power failures, which struck on January 29.
"That occurred when the ship was at anchor and was after the ship had offloaded 88 tonnes of humanitarian stores on January 26," Vice Admiral Noonan said.
He confirmed to the committee that power was restored "within a matter of hours" but, on January 30, HMAS Adelaide suffered a second power failure.
"This time it was as a result of a fault on the gas turbine, not on the same diesel generator that [the failure] had occurred the previous day."
He said emergency power was restored within two minutes, and full power over the course of the day.
A thorough investigation was undertaken on the landing helicopter dock to get it up to full capability, which was restored the following day.
"The exact nature of the reason for these power failures is part of an ongoing, technical investigation, but I can confirm it was not a single point of failure."
Last week, the ADF's Chief of Joint Operations, Lieutenant General Greg Bilton, confirmed one fifth of the crew on board HMAS Adelaide had contracted COVID-19 during the deployment.
On Tuesday, two Chinese warships from the People's Liberation Army's southern theatre command arrived in Tonga to deliver relief supplies, including walkie-talkies and temporary housing to the devastated Pacific nation.
