The same kind of military truck that overturned and injured 18 soldiers in Sydney was previously involved in two other roll-over incidents, the army says.
The open-top vehicle careered off the side of the road and rolled several times during a defence exercise at Holsworthy Barracks on Monday.
But the Australian Army on Tuesday defended the safety record of the Mercedes-Benz Unimog, saying it is a 'very reliable workhorse'.
'Our soldiers, who are trained to look after those vehicles, and our technical standards for looking after those vehicles, are of the highest possible level,' Colonel David Smith, Acting Chief-of-Staff for Forces Command, told reporters in Sydney.
'I have every confidence in the Unimog as a safe vehicle that's fit for purpose.'
Col Smith said the trucks had been involved in two previous rollovers during their 30 years of service.
'When you look at the usage rate of the vehicle and compare it to the number of incidents that have occurred, the number of accidents that have occurred are well below the national average,' he said.
Soldiers riding on board the vehicle on Monday were thrown out when it rolled, leaving a 21-year-old in a critical condition and two others in intensive care.
They are among six who remain in St George, Westmead and Liverpool hospitals.
Twelve of the remaining injured soldiers have been released and are now being cared for in a military facility in Holsworthy.
An Army spokeswoman said the multi-purpose truck normally carries 16 personnel, plus equipment.
It's unknown whether the truck exceeded the speed limit but NSW Police Inspector Steve Blair on Monday said speed may have been a factor.
Defence Force Association executive director Neil James told ABC radio earlier on Tuesday that the model of truck involved was old and overdue for replacement.
'In their day they were an absolutely superb vehicle, but for a vehicle introduced in the mid-1980s they're getting near the end of their service life,' he said on Tuesday.