The truck fire in an underground mine passage at the Newmont Waihi gold mine in July is believed to have started in the vehicle's hydraulics under the cab and out of reach of automatic fire extinguishers.

A miner, who was not the driver of the truck, was fired because he failed to follow emergency procedures during the fire in the underground mine on July 17.

The Komatsu truck that caught fire in the Newmont underground gold mine in Waihi.

An incident report into the truck fire that closed down the Newmont Gold's Trio and Favona mine for three days was released on Wednesday.

Newmont operations manager Steve Price's report says the driver of the 30 tonne dump truck noticed a burning smell as he was driving towards the mine entrance near the end of the shift.

He saw a bright spark from the side of the engine bay at about 5.18am, and whitish smoke.

He stopped the truck, reversed it into a nearby layby, called an emergency on the two way radio and exited the cab, which was filled with smoke. The on board automatic fire suppression system activated as designed, but was ineffective.

The driver was able to get a lift to the mine entrance portal from another truck that was following close behind.

The stench gas – a harmless gas that smells like rotten eggs added as a warning to the ventilation system in an emergency - was activated and all 28 personnel underground proceeded to their closest refuge chambers where they waited for advice/rescue. All were safely rescued from the mine by 12pm and the fire was allowed to burn out.

The report states the design of the trucks' automated fire suppression system covers the major hot spots within the engine compartment, the turbo – fuel/oil lines – exhaust, but does not extend to the underside of cab where the hydraulic componentry is located.

The Komatsu 300 – 2 dump trucks are modified for mining work. Outer components can be susceptible to damage as was the case with the hydraulic tank on UDTX1001.

The report states damage to the hydraulic tank may have been a contributing factor and as such engineered guarding needs to be incorporated into the site specifications.

When trucks sustain damage on or around the hydraulic tank, a full inspection of componentry associated with the tank needs to be undertaken by a qualified tradesman. This requires the cab to be lifted for this specific piece of equipment.

The hydraulic area where the fire started cannot be visually inspected during a pre-start check due to the location underneath the operator's cabin. The only indication of a potential issue would be oil dripping on the ground below the componentry.

The report states the new Komatsu was purchased in 2007 and was due for replacement later this year.

Newmont is recommending an inspection of the entire truck fleet to ensure all high risk hoses and attachment points are inspected for integrity.

Engineers will be consulted regarding guards around hydraulic oil tanks. Fixed tube hydraulic lines will be replaced with flexible tubing on the return line.

The fire suppression system design will be reviewed.

Engineers will also consider relocating hydraulic lines and/or additional sheath/shield over hydrocarbon, coolant lines and turbo.