There are 5 levels of maintenance

Level 1

Simple adjustments recommended by the manufacturer using accessible elements with no dismantling or opening of the equipment, or changing accessible elements in complete safety, such as indicator lamps or certain fuses.

Level 2

Repair by standard exchange of elements provided for this purpose and minor preventive maintenance operations, such as greasing or checking proper functioning.

Level 3

Identification and diagnosis of breakdowns, repairs by changing components or functional elements, minor mechanical repairs and all normal preventive maintenance operations such as general adjustment or realignment of measuring instruments.

Level 4

All major corrective or preventive maintenance work with the exception of renovation and reconstruction. This level also includes adjusting the measurement instruments used for maintenance and verification of working standard gauges by approved organisations.

Level 5

Modernisation, reconstruction or execution of major repairs entrusted to a central workshop or an external unit.