Fire on explosive charge vehicle while at a charged faceMines safety alert no. 369 | 04 December 2019 | Version 1
Upon restarting the machine, the engine went into an uncontrolled over speed. Several unsuccessful attempts were made to shut the engine down, including by using the ignition key; E Stop; AFFF and discharging a fire extinguisher into the air intake.
How did it happen?
The engine fuel system was a unit pump design with a common fuel rack connecting all unit pumps.
Each unit pump was timed with the fuel rack to ensure the fuel quantity control was uniform across all cylinders. The fuel rack was located within the engine block. During normal operation, when the engine stop solenoid is de-energized, the governor moves the fuel control rack into the no fuel position and the fuel rack defaults to the full fuel position when the engine is not running but ready to start. The governor controls the engine speed with the fuel rack position once the engine starts.
On starting the engine, the speed governor, stop solenoid, E-stop and throttle control did not have any impact on the engine speed or stop the engine due to the fuel rack being jammed in the full fuel position.
- Stopping fuel to the engine with a fuel shut off valve on the fuel supply, or
- Stopping air supply to the engine with an air shutdown flap installed to the air intake system.
2. OEM or OEM equivalent parts (including bolts and fasteners) should be used when conducting repairs and maintenance on critical or safety systems.
3. The OEM instructions should be followed when conducting repairs that are unfamiliar, complex or to critical systems (such as the fuel system).
4. Audit fuel systems on mobile plant for damage, fuel leaks or residual fire hazards.
Authorised by Hermann Fasching - Chief Inspector (Mineral Mines and Quarries)
Contact: Trevor Brown, Acting Deputy Chief Inspector (Mineral Mines and Quarries), +61 7 4447 9253 QldMinesInspectorate@dnrme.qld.gov.au
Issued by the Queensland Department of Natural Resources, Mines and Energy