Throughout a number of incident investigations and audits, the DPI said there appeared to be "inconsistency in incident notifications from underground coal operations" in regard to reporting the failure of explosion-protected elements of diesel engines.

Such incidents are required under the Coal Mine Health and Safety Regulation 2006 to be reported to the chief inspector and the industry check inspector.

The DPI provided a list of some of the incidents that need to be reported, including:

• Explosion-protection characteristic failures discovered during routine maintenance activities;
• Failure of a diesel engine system to shut down when required by control sensors; for example, loss of water in the scrubber or excessive system temperatures (above 150C);
• Failure of a primary and back-up control sensor; for example, temperature, floats;
• Looseness of any explosion-protected fixed joint; for example, a gasket joint;
• Failure to replace any explosion-protected component, such as a cap, plug, flame-trap or other component, after carrying out maintenance activities; and
• The water level not being at or above the minimum safe water level when the diesel engine shuts down automatically.