A Mechanical Drive Truck (MDT) in a mining area of Kalimantan, caught on fire while it was being operated and while waiting to be filled with soil.
The driver of the MDT was alerted to the fire by another truck driver. The MDT’s driver tried to fight the fire using portable fire extinguisher available on the MDT but to no avail. The fire was only extinguished around 5 hours later with the help of 2 firefighting tenders and an excavator.
During AGI’s inspection, the entire MDT was found to have been affected by the fire. The front offside tyre was dislodged from the axle whilst the front nearside and rear offside tyre was consumed by the fire. A “V”-pattern was observed on the nearside of the MDT which indicated that the fire had initiated from the undercarriage.
The batteries within the batteries compartment were badly affected by the fire, exposing the metal plates of the batteries. Most of the cables’ insulation was consumed by the fire, exposing the copper within.
These copper cables connect the batteries’ terminals to the battery relay through an opening in the battery compartment (red arrow).
Examination of the engine compartment revealed that there were still remnants of aluminium cover on the offside section of the engine whilst the entire nearside aluminium cover of the engine had melted, indicating that the fire was more severe at the nearside of the engine.
The MDT is equipped with two (2) starter motors units and both are directly connected to the battery relay units. Each of the starter motors are supplied with 24 volts DC power from the batteries through the battery relay units. The battery relay units are connected to the starter motors via 2 joint electrical cables. Both starter motors were badly damaged by the fire where the bodies had melted, exposing the inner gear within it.
The starter motors terminal fractured due to fatigue, causing a live cable dangled and swing as the truck moved.
The body and parts of the MDT served as the grounding point for the electrical system. As the dangling cable came into contact with the metallic part of the vehicle, a spark was produced. The temperature of a spark can easily reach the temperatures exceeding 5,000°C. A fire developed when the spark came in contact with the left bank fuel hose, which is combustible, burning the hose and the air-fuel mixture from the leaking hose. The fire developed due to spark when the dangling live cable came in contact with body of the MDT.