mobile logo

featured image

Fire to a Mechanical Drive Truck

posted on April 4, 2018 / IN Fire and Explosion Investigation /

Fire on Truck or Truck on Fire?

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.

The Mechanical Drive Truck (MDT) shows a "V" -pattern on its nearside.
The Mechanical Drive Truck (MDT) shows a “V”-pattern on its nearside.

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.

Fire affected batteries in the truck's batteries compartment.
Fire affected batteries in the MDT’s batteries compartment.

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).

2 copper cables run through this opening. 1 of the cables (red arrows) had arched to the battery compartment housing.
2 copper cables run through this opening. 1 of the cables (red arrows) had arced to the battery compartment housing.
The MDT engine compartment.
The MDT’s engine compartment.

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 has two (2) starter motors that are badly affected by fire.
The MDT has two (2) starter motors that are badly affected by fire.

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 electrical cables connected to the starter motors were removed for a closer inspection. One (1) part of the cable revealed signs of molten copper (red arrow) with a protruding shape. Another cable was found with a terminal.
The electrical cables connected to the starter motors were removed for a closer inspection. One (1) part of the cable revealed signs of molten copper (red arrow) with a protruding shape. Another cable was found with part of a terminal.
A portion of the terminal was found with a fractured mark (red arrow) which initially was connected to the cable with molten copper with a protruding shape.
A portion of the terminal was found with a fractured mark (red arrow) which initially was connected to the cable with molten copper with a protruding shape.

Analysis

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.

Conclusion

The fire developed due to spark when the dangling live cable came in contact with body of the MDT.

By Rosadli Rosli

During the course of his work, Rosadli Rosli has carried out various cases of accidents and system failures involving fire, explosions, vehicle accident investigation and reconstruction, vehicle engine identification, failure analysis of electrical, electronic and mechanical equipment in power plants and in machines, failure cases in metallurgical industry, spontaneous combustion in agricultural industries, lightning damage and hot works investigation.

AGI’s Professional Restoration