Victorian firefighting aircrane Elvis has broken down for the second time in a week, this time with a mechanical fault.

Elvis was grounded on Friday afternoon after suffering hydraulic issues while working at the bushfires in Victoria's east.

The aircraft will be out of action for at least three days and replaced with aircrane Gypsy Lady while it is being repaired.

Benign weather conditions overnight have slowed down a 50,000-hectare fire, which started in the Baw Baw National Park on Thursday night and spread rapidly on Friday destroying nine homes in nearby areas.

Fire Services Commissioner Craig Lapsley said there are 14 aircraft currently fighting the fires.

"The slightly cooler conditions across the state, and short flight times, have allowed us to place additional resources on stand-by for the Gippsland fires," Mr Lapsley said in a statement on Saturday.

"We will monitor the situation, including lightning strikes that occurred in the north-east overnight, before determining where and when the additional resources will be deployed."

Five fire bombers, three-fixed wing fire bombers, five light air attack supervision helicopters and one fixed wing firespotter are being used to tackle the Gippsland fires.

More than 270 personnel and 70 trucks are also on site fighting the fires.

Elvis' current woes are unrelated to engine trouble it experienced earlier this week.

Elvis was forced to undergo repair after experiencing a problem with one of its two engines fighting a fire at Little River, southwest of Melbourne, on Monday.