In SAP, time-based preventive maintenance is a process that involves creating maintenance plans that are based on time intervals. This means that maintenance activities are performed at regular intervals, regardless of the equipment's operating condition. SAP system provides wide variety of scheduling parameters, which gives us possibility to setup the preventive maintenance program according to our needs. They define how often maintenance tasks should be performed on equipment based on a predefined time interval. These parameters are set up in the maintenance plan and control the timing of preventive maintenance tasks. Some common scheduling parameters for time-based preventive maintenance in SAP PM include:

1. Maintenance Cycle: This parameter determines the frequency at which maintenance tasks are performed on the equipment. The maintenance cycle can be defined in months, weeks, days, or hours, and is used to schedule maintenance tasks at regular intervals.
2. Scheduling Indicator: Defines the planned dates of your maintenance plan. We have 3 options - Time 
(fixed calculation, a month has always 30 days), Time - Factory Calendar (like the previous one + only the factory cal. days are counted), Time - Key date 
(effective days of a month).
3. Call Horizon: We enter it in % or number of days. It specifies, when an order should be created in the system for a calculated maintenance date. In other words - how much time should pass between the current and future order before it is created in the system. By created we mean - just available in the system, the planned dates are something different.

There is plenty of other parameters like shift factor (late and early completion), cycle modification factor, factory calendar, scheduling period, start of cycle and others. Overall, these scheduling parameters help ensure that preventive maintenance tasks are performed at the appropriate intervals, maximizing equipment uptime and minimizing downtime due to equipment failures. Download the free illustration with all the scheduling parameters for time-based preventive maintenance program in SAP Plant Maintenance by SAPdude.