Which type of maintenance is typically scheduled and documented in the 3-M System?

Planned maintenance is a systematic approach that is essential in the 3-M System, as it ensures that maintenance activities are carried out at scheduled intervals to prevent equipment failures and to optimize performance. This type of maintenance is meticulously documented within the system, allowing for better tracking of maintenance tasks, compliance with regulatory standards, and resource allocation.

Planned maintenance activities are part of a structured schedule based on usage and manufacturers' recommendations, meaning they are less dependent on the immediate condition of equipment and more about adhering to a predetermined maintenance calendar. This strategy ultimately helps in maintaining operational readiness and prolonging the lifespan of equipment.

In contrast, the other types of maintenance mentioned—unscheduled repairs, reactive maintenance, and ad-hoc maintenance—do not follow a systematic schedule and are typically performed as a response to unexpected failures or as needed. They lack the documentation and pre-emptive planning found in the planned maintenance approach of the 3-M System.