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Mines safety alert no. 327 | 10 June 2016 | Version 1

Uncontrolled engine shutdown on a dump truck

What happened?

A Caterpillar 777F rear dump truck was travelling down a ROM ramp when it lost engine power resulting in the truck wheels locking on and the truck sliding for approximately 60 metres, coming to a halt on the haul road. The emergency steering allowed the operator to retain control of the truck. No injuries to personnel were incurred.

How did it happen?

A non-genuine relay, installed for the Automatic Fire Suppression System, had been dislodged and worked loose from its position due to vibration. The relay was installed to control power supply between the fire suppression system control module, engine electronic control module and the 'E Stop' switches.

When the relay dislodged it open circuited the power supply to the engine electronic control module, causing the truck engine to suddenly shutdown without warning.

Recommendations

  1. All vehicles fitted with fire suppression systems should comply with the requirements of the relevant Australian Standards, in particular AS 5062-2006 Fire protection for mobile and transportable equipment.
  2. Sites should inspect all mobile fleet fitted with an automatic fire suppression system to ensure the installation and wiring configuration do not create further hazards during operation. If the power supply to a fire suppression control system is interrupted, it should have the ability to warn the operator, and not simultaneously shut down the vehicle's engine without warning.
  3. Sites should risk assess all mobile fleet fitted with an automatic fire suppression system to determine the most effective system discharge timing, taking into consideration the operating environment and machine use.

Investigations are ongoing and further information may be published as it becomes available. The information in this publication is what is known at the time of writing.

We issue Safety Notices to draw attention to the occurrence of a serious incident, raise awareness of risks, and prompt assessment of your existing controls.

Comments

The site's six-monthly inspection regime for automatic fire suppression systems did not include an inspection of this particular relay.

The fire suppression system did not discharge during the incident.

Authorised by Hermann Fasching - Manager, Safety and Health, North Region

Contact: Alan Graham, Inspector of Mines , +61 7 4447 9250

Issued by Queensland Department of Natural Resources and Mines

Placement: Place this announcement on noticeboards and ensure all relevant people in your organisation receive a copy.