Mobile plant is the backbone of Australian mining operations — from the giant excavators of the Pilbara to the drill rigs of the Goldfields and the dozer fleets of Queensland coal operations. Managing mobile plant safely and compliantly requires a structured inspection regime that covers pre-start checks, periodic condition inspections, and formal certification. This guide outlines what is required under Australian mining legislation and how leading operators structure their mobile plant inspection programs.
What is Mobile Plant Under Australian Mining Law
Mobile plant includes any plant that moves or can be moved under its own power or is capable of being moved during normal operation. Under the Western Australian MSIR, mobile plant is defined broadly to include excavators, haul trucks, front-end loaders, motor graders, bulldozers, scraper units, articulated dump trucks, light vehicles used on mine roads, and any other self-propelled or towed equipment operating on the mine site.
The key legislative obligations for mobile plant attach to the person in management or control of the mine (typically the mine manager or principal employer), the plant owner where different from the operator, and any contractor who brings plant onto the site. All three parties carry duties that cannot be fully contracted away.
Pre-Start Inspection Requirements
Pre-start inspections are required before each operating shift and must be documented. The purpose of the pre-start is to confirm that the plant is in a safe operating condition for the shift ahead — not to discover major defects that should have been identified at a previous periodic inspection. A well-structured pre-start checklist covers engine and cooling systems, hydraulic systems, tyres or tracks and undercarriage, operator cabin including ROPS/FOPS integrity, lights and signals, brakes and steering, payload systems where fitted, and any safety devices specific to the machine type.
Pre-start records must be retained and available to inspectors. The operator who completes the pre-start should sign the record. Any defects identified that cannot be immediately rectified must trigger a plant quarantine process — the plant should not be operated until the defect is assessed and cleared by a competent person.
Periodic Condition Inspections
Beyond daily pre-starts, mobile plant requires periodic condition inspections carried out by a competent person with the qualifications and experience to identify structural, mechanical, and safety-related defects. These inspections typically occur at intervals driven by operating hours (e.g., every 250, 500, 1000, or 2000 hours) or calendar intervals, whichever comes first.
A periodic inspection for a large excavator or haul truck should cover structural integrity of the main frame, boom/arm/bucket or body structure including weld quality and crack detection; hydraulic system condition including cylinder rod, hose, and fitting integrity; drivetrain, axle, and wheel hub condition; brake system performance and component wear; electrical systems and safety interlocks; cab integrity including ROPS/FOPS rating compliance; and all operator-protection systems.
The inspection should be carried out using a documented scope that is appropriate to the plant type and age. An older machine operating in a corrosive or high-duty-cycle environment may require more frequent or more detailed inspection than a newer machine in less demanding conditions.
Introduction Inspection — New Plant Arriving on Site
Before plant is placed into service at a mine site for the first time — whether purchased new, acquired second-hand, or transferred from another site — an introduction inspection should be completed. This is a requirement under the Western Australian MSIR and is considered best practice across all Australian jurisdictions.
The introduction inspection verifies that the plant is in a fit state to commence service, that all required safety devices are present and functional, that appropriate guarding and operator protection is fitted, and that the plant's documentation (design registration where required, previous inspection records, operator's manual) is available.
Competency Requirements for Mobile Plant Inspection
The person conducting a periodic inspection of mobile plant must have the knowledge and experience appropriate to the plant type and size. For most categories of mobile plant, this means a qualified mechanic or engineer with documented experience in the relevant plant type. For structural inspections involving weld assessment or crack detection, a qualified welding inspector or NDT practitioner may be required.
Inspectors conducting formal periodic inspections should be distinguishable from the maintenance technicians responsible for day-to-day servicing. An inspector's role is to form and document an independent assessment of the plant's condition and fitness for service. Where the same person both maintains and inspects plant, there is a conflict of interest that regulators may question.
Evidence base for procurement
Public sources · reviewed 19 Sep 2026These regulator and standards sources provide the public basis for the inspection context on this page. They describe requirements and application context; they do not claim that Mining Inspection Australia holds a qualification, accreditation or project history.
Safe Work Australia
The model framework for plant duties, inspection, maintenance and records; check the adopted law in the relevant jurisdiction.
Safe Work Australia
Risk controls, regular inspection and testing, repair or replacement of plant, and the records that support those controls.
NSW Resources Regulator
An example of the NSW mine inspection framework, including procedures, timing and competent persons under section 39 of the WHS (Mines and Petroleum Sites) Regulation 2022.
Frequently asked questions
Are mobile plant inspection records required to be kept on site?
Records must be available to the mine manager and regulators. They can be held electronically and accessed from site or a central location, but must be retrievable on request. In WA, the MSIR requires plant inspection records to be kept for the life of the plant.
What happens if mobile plant fails a periodic inspection?
Plant that fails a periodic inspection should be taken out of service until the defects are rectified. The plant should be quarantined and clearly tagged to prevent inadvertent use. Once repaired, a follow-up inspection should confirm the plant is fit to return to service before it is re-deployed.
Does hired plant need to be inspected before use on a mine site?
Yes. The principal employer or mine operator has a duty to ensure that hired plant is fit for use on their site, regardless of any previous inspection by the hire company. An introduction inspection and verification of current certification should be completed before deployment.
How are high-hours machines treated differently in inspection programs?
High-hours machines carry a higher accumulated fatigue load and typically present more wear-related defects. Responsible operators apply shorter inspection intervals to high-hours machines and include enhanced structural inspection including NDT weld assessment as part of the periodic scope.