Preventive maintenance forecast logic

You can generate a forecast by using the Generate Forecast action in the Preventive Maintenance application, or by using the PM Forecast cron task. When you forecast a preventive maintenance (PM) record, the forecast is generated based on the frequency criteria that are specified on the Frequency tab, and seasonal information. The generated forecast appears on the Forecast tab of the Preventive Maintenance application.

The forecast logic is as follows:

Time-based PMs

When a PM is time-based, the Estimated Next Due Date is calculated by taking the current date and adding the frequency and frequency units to it. For example, a Frequency of 3 with a Frequency Unit of days would add three days to the current date. The Estimated Next Due Date then becomes the first forecasted PM date. Subsequent forecasted dates continue in the same frequency until the end of the forecast duration. Seasonal information, such as active days and dates, is taken into account during forecasting.

Meter-based PMs

When a PM is meter-based, the forecast uses the value in the Average Meter Units/Day field to determine the Estimated Next Due Date. Subsequent forecasted dates are determined by the Average Meter Units/Day value. Because a meter-based forecast is generated based on average meter units, any change to the average deletes the forecast. No forecast is generated if the last meter reading date is null or if the Average Meter Units/Day is zero. When the Average Meter Units/Day change, the forecast is deleted. Seasonal information, such as active days and dates, is taken into account during forecasting.

Seasonal dates

Seasonal Dates are taken into account during forecasting. If the projected forecast date for a PM occurs in an inactive season, the PM is forecasted on the earliest date in an active season (that occurs after the Next Due Date).

Target start dates

If the Use Last Work Order's Start Date to Calculate Next Due Date field is selected, the PM is forecasted based on the Estimated Next Due Date of the previous PM record. If the field is not selected (meaning that the next PM forecast is calculated based on the completion date of the previous forecasted instance), the forecast is based on the previous forecast date plus the job plan duration from the job plan that is associated with the PM. If no job plan duration is available for the PM, the forecast is based solely on the frequency criteria.

Extended dates

If a PM contains an Extended Date on its Frequency tab, the Extended Date overrides the Estimated Next Due Date in a forecast. The first forecasted date is equal to the Extended Date. All subsequent forecasts, however, are based on the Estimated Next Due Date, not the Extended Date, unless the Adjust Next Due Date check box is selected. For example, a PM has a frequency of three days, an Estimated Next Due Date of December 1, and an Extended Date of December 2. The Adjust Next Due Date check box is cleared (set to No). When a forecast is generated, the first forecast date is December 2. Subsequent forecast dates (based on the Estimated Next Due Date of December 1) are December 4, December 7.

When a forecast has been generated, the Extended Date is cleared, and the field becomes read-only. Any changes to the forecast dates must be entered in the New Date field.

When a forecast exists

When a forecast exists for a PM record, you can extend the forecast period by changing the date in the Forecast Until field in the Generate Forecast window. If the date you enter is after the date in the Last Forecast Date field, the new forecast dates are added to the existing forecast on the Forecast tab. The date that you enter in the Forecast Until field must be a date that is 30 days after the Last Forecast Date.

For example, if the Last Forecast Date of a PM is 12/31/2009, and you enter 02/28/2010 in the Forecast Until field, any forecasted dates between December 31 and February 28 are added to the existing forecast on the Forecast tab.

Duplicated PMs

When you duplicate a PM record, forecasts that exist for the original record are not duplicated. To generate forecasts for the new PM, select Generate Forecast action, or wait for the PM Forecast cron task to run.

PM hierarchies

Child PMs are forecasted when a Parent PM is forecasted.



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