Editing schedule information for the maintenance program

This page enables you to define the schedules for carrying out the maintenance program. Tell me more

Select the “Edit Schedule Information” link in the “Create Aircraft Maintenance Program” or the “Edit Aircraft Maintenance Program” page.

The “Edit Schedule Information” page appears.

The system displays the following field:

Date Format

The format in which the date fields are displayed and to be entered, in this page. This format is displayed from the "User Preferences" business component based on the login user ID. In case the format is not defined, the system displays the date format from the "Enterprise Modeling" business component by default.

The system displays the following fields in the “Maintenance Program Information” group box:

Maintenance Program #	The maintenance program for which the schedule information must be specified.
Revision #	The revision number of the maintenance program.
Program Desc.	The description of the maintenance program.
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Status	The status of the maintenance program, which can be “Fresh”, “Active”, “Inactive” or “Return”.

Enter the following field in the “Work Unit Details” group box:

Work Unit #

Use the drop-down list box to select the work unit for which the dependent work units must be specified. The system lists all the work units specified for the maintenance program along with the sequence numbers.

Click the “Get Details” pushbutton.

The system displays the following details:

Work Unit Desc	The description of the work unit.
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Work Unit Type	The type of the work unit, which can be “Task”, “Standard Procedure”, “Aircraft Work Package” or “Component work Package”.
Execution Type	The execution type of the work unit, which can be “Major” or “Minor”.
Job Type	Indicates whether the work unit must be performed on the aircraft or on the components fitted to the aircraft. The system displays either “Aircraft” or “On-wing”.

Enter the following fields in the “Schedule Details” group box:

Schedule Type

Use the drop-down list box to specify whether the work unit must be executed only once or repeated at certain intervals. The system provides the following options:

One Time – Select this option if the work unit must be executed only once.
Recurring – Select this option if the work unit execution must be repeated at certain defined intervals.

Update Basis

Use the drop-down list box to select the mode by which the due dates for executing the work units must be calculated. The system provides the following options:

Schedule – If the option is selected as “Scheduled”, then NSD/NSV (Next Schedule Date/ Next Schedule Value) for executing the work units will be calculated based on a scheduled fixed interval.
Actual Completion – If the option is selected as “Actual Completion”, then NSD/ NSV will be calculated by adding the Repeat Fixed / Floating Interval value to the date or value at which the work unit is actually executed.
Time Window – This option is applicable for the following conditions:

Within the Tolerance limits: If the option is selected as “Time Window”, then NSD/NSV will be calculated based on a scheduled fixed interval
Beyond the Tolerance limits: If the option is selected as “Time Window”, then NSD/NSV will be calculated by adding the Repeat Fixed / Floating Interval value to the date or value at which the work unit is actually executed.

Example

Assume that the scheduled date for a work unit is 11-10-2003. If tolerance value is specified as +/-2 days, the Earliest schedule date for the work unit is 09.10.2003 and Latest schedule date for the work unit is 13.10.2003 (inclusive of 9.10.2003 and 13.10.2003) and the repeat interval is set as 20 days.

If the “Update Basis” is selected as “Schedule”, and if the work unit was executed on 10.10.2003 (within the specified limits) then the next schedule date of the work unit is 31.10.2003 (The NSD for the work unit is based on a fixed interval of 20 days irrespective of when the work was executed (11.10.2003+ 20 days (Repeat Interval)).
If the “Update Basis” is selected as “Actual Completion”, and if the work unit was executed on 09.10.2003 (within the specified limits) then the next schedule date of the work unit is 29.10.2003 (ie 09.10.2003+20 days (Repeat Interval)).
If the “Update Basis” is selected as “Time Window”,
1. If the work unit was executed on 10.10.2003 (within the specified limits) then the next schedule date of the work unit is 30.10.2003. (10.10.2003+20days).
2. If the work unit was executed on 05.10.2003 (beyond the specified limits) then the next schedule date of the work unit is 25.10.2003 (05.10.2003+20days).
3. If both date based and usage based schedules are defined for the work unit then the “Sch.Exe Rule” (Values “Earliest” and “Latest”) identified for the work unit in the maintenance program will be considered.

The system leaves the field blank by default.

Enter the following fields in the “Date Based Schedule Details” group box:

Time Unit

Use the drop-down list box to specify the time unit for the date-based schedule. The system provides the options ”Days”, “Months”, “Month End” and “Years”.

Reference Date Basis

Use the drop-down list box to specify the reference date based on which the schedules for the work unit must be ascertained. The system provides the following options:

Operational Date – Select this option if the schedules for executing the work units must be calculated based on the operational date of the aircraft.
Induction Date – Select this option if the schedules for executing the work units must be calculated based on the induction date of the aircraft.

If you leave the field blank, then the last performed date of the work unit must be specified for calculating the schedules for the work unit.

Threshold Interval

The interval at which the first execution of the work unit takes places (Decimal). Data entry in this field is mandatory if you are specifying date based schedule and if the “Schedule Type” field is set to “One Time”. For a task with both date-based and parameter-based schedules, you must specify one of the below-listed,

Threshold interval for date based schedule
Threshold interval for at least one parameter of the usage-based schedule.

Alert Interval	The period at which an alert message must be displayed about an impending due date for performing the work unit (Decimal). Ensure that you enter a non-negative value in this field. Also, ensure that the value entered in this field is greater than the sum of the “Threshold Interval” and “Positive Tolerance”.
Positive Tolerance	The maximum time period subsequent to the next schedule date, within which the work unit must be performed (Decimal). Ensure that the value in this field is positive.
Negative Tolerance	The maximum time period ahead of the next schedule date, within which the work unit could be performed (Decimal). Ensure that the value in this field is positive.
Repeat Fixed Interval	The interval after which the work unit must be repeated irrespective of whether its previous execution is completed or not (Decimal). Ensure the following: Specify the interval period only when the “Schedule Type” field has been set to “Recurring”. Enter a positive value in this field The value is greater than the value entered in the “Positive Tolerance” and “Negative Tolerance” fields

Repeat Floating Interval

The interval after which the work unit must be repeated, from the period of its last execution and completion (Decimal). Ensure the following:

Specify the interval period only when the “Schedule Type” field has been set to “Recurring”.
Enter a positive value in this field
The value is greater than the value entered in the “Positive Tolerance” and “Negative Tolerance” fields

Note: You must specify either Fixed Interval or Repeat Floating Interval for a date-based recurring task. However, for a recurring task with both date-based and usage-based schedules, you must specify

Repeat Fixed Interval or Repeat Floating Interval in date-based schedule (or)

Repeat Fixed Interval or Repeat Floating Interval in usage-based schedule for at least one of the parameters.

Terminating Interval

The period, reaching which the work on the work unit must be terminated (Decimal). Ensure that you enter this field only when the “Schedule Type” field has been set to “Recurring”. Also, ensure that you enter a non-negative value in this field.

Enter the following fields in the “Usage Based Schedule Details” multiline:

Parameter

The parameter based on which the work unit must be performed (Alphanumeric, 30). Ensure that the parameter is defined in the “Create Parameter” activity of the “Aircraft” business component and is specified for the aircraft. Also, ensure that the parameter is of type “Consumption”.

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The system displays the following field:

UOM	The unit of measurement defined for the parameter.

Enter the following fields:

Threshold Value

The parameter value at which the first execution of the work unit is due (Decimal). Ensure that you enter a positive value in this field. Data entry in this field is mandatory if you are specifying usage-based schedules and if the “Schedule Type” field is set to “One Time”. If the usage-based schedule for a task comprises of many parameters, you may specify threshold value for a minimum of one of the parameters. However, if the usage-based schedule comprises of single parameter, threshold value is mandatory for the lone parameter. For a task with both date-based and usage-based schedules, you may specify one of the below-listed,

Threshold interval for date based schedule
Threshold interval for at least one parameter of the usage-based schedule.

Repeat Fixed Interval

The interval after which the work unit must be repeated irrespective of the completion of its last execution (Decimal). Ensure the following:

Specify the interval period only when the “Schedule Type” field has been set to “Recurring”.
Enter a positive value in this field
The value is greater than the value entered in the “Positive Tolerance” and “Negative Tolerance” fields

Note: For example, if the repeat fixed interval is 100 flight hours, the work unit would be repeated after the expiry of 100 flight hours of the aircraft, irrespective of whether the previous execution of the work unit was completed or not.

Repeat Floating Interval

The interval after which the execution of the work unit must be repeated, from the period when it was last executed (Decimal). Ensure the following:

Specify the interval period only when the “Schedule Type” field has been set to “Recurring”.
Enter a positive value in this field
The value is greater than the value entered in the “Positive Tolerance” and “Negative Tolerance” fields

Note: If the usage-based schedule for a task comprises of many parameters, you must specify repeat fixed interval or the repeat floating interval for a minimum of one of the parameters. However, if the usage-based schedule comprises of single parameter, repeat fixed interval or repeat floating interval is mandatory for the lone parameter. For a task with both date-based and usage-based schedules, you must specify one of the below-listed,

1. Repeat fixed interval or repeat floating interval for date based schedule

2. Repeat fixed Interval or the repeat floating interval for a minimum of one parameter of the usage-based schedule.

Alert Interval	The parameter value at which an alert message would be displayed about an impending work due on the work unit (Decimal). Ensure that you enter a positive value in this field.
Positive Tolerance	The upper limit of the parameter value greater than the next schedule value, within which the work unit must be performed (Decimal). Ensure that you enter a positive value in this field.
Negative Tolerance	The lower limit of the parameter value lesser than the next schedule value, within which the work unit could be performed (Decimal). Ensure that you enter a positive value in this field.
Terminating Value	The parameter value, reaching which the work on the work unit must be terminated (Decimal). Ensure that you enter a positive value in this field.

The system displays the following field on clicking the “Edit Schedules” pushbutton.

Parameter Description

The description of the parameter.

Click the “Edit Schedules” pushbutton to save the schedule details against the maintenance program.

If the Eng. doc reference # exists for the task, the system allows you to modify the following Eng. Doc. task schedule details in the Maintenance Program, only if the process parameter “Allow modification of Eng. Doc. task in Maintenance Program” is set as “Allowed” in the “Define Process Entities” activity of the “Common Master” business component.

Schedule Type
Update Basis
Date Based Schedule details
Usage Based Schedule details

Computation of Next Schedule Date (NSD) / Next Schedule Value (NSV)

If you specify “Initiated/Reset by” for a task in an aircraft maintenance program as "Related Task Compliance”, then system does not automatically compute the NSD/ NSV. However, if you have specified the NSD/ NSV, the system retains these values.
Computation of NSD / NSV based on ‘Change Type’:

If the ‘Change Type’ is set as “Correction”, on modification of interval, NSV needs to be recomputed based on:
- Threshold value or Repeat Interval if task is not complied at least once.
- ‘Update Basis’ (Time Window, Schedule or Actual Completion) set in the last instance of compliance.

If the ‘Change Type’ is set as “Correction”, on modification of interval, NSD needs to be recomputed based on:
- "Reference Basis" (Induction or Operational date) if task is not complied at least once.
- ‘Update Basis’ (Time Window, Schedule or Actual Completion) set in the last instance of compliance.

If the ‘Change Type’ is set as “Re-baseline”, on modification of interval:
- On re-baseline of LPD / LPV, NSD / NSV must be computed based on re-baselined LPD / LPV.
- On re-baseline of NSD / NSV, NSD / NSV must not be recomputed.

To proceed carry out the following:

Select the "Edit Dependent Schedule Information” link at the bottom of the page to specify schedules for dependent work units.

Note: You cannot traverse to this page if there are no dependent work units defined for the work unit selected in the “Work Unit #” field.

Editing schedule information for the maintenance program – An overview

The periodicity of a maintenance activity is defined in the form of schedules. Schedules are defined here for executing the various work units as a part of the maintenance program. Using these schedules, you can forecast the maintenance activities that are due for an aircraft in the “Aircraft Maintenance Forecast” business component. Work orders are generated based on these schedules in the “Hangar Work Order” business component.

Schedules for executing the work units can be defined either for specific time intervals or based on the usage of the aircraft. Schedules can be date based or usage based. Usage and date-based schedules can be of two types, namely, “One time” and “Recurring”:

One time schedule:

One-time schedules are used for carrying out one time execution of maintenance program entities on a specified date or on attaining a specified value for the consumption parameter of the aircraft.

Recurring schedules:

Recurring schedules are used for execution of repetitive maintenance program entities pertaining to either usage based or date-based schedules. A recurring schedule can be of a “Fixed Interval” type or a “Floating Interval” type.

Date Based Schedule:

Date-based schedules are performed at certain time intervals (for example in two-week or six-month cycles). These schedules are used when the maintenance activities on the aircraft must be performed at fixed intervals. Date based schedules have their periodicity defined in terms of calendar days. The schedule for the next performance of the maintenance activity is specified in terms of a calendar date. For example, if a work unit must be performed on the tenth day of every month and if this is defined as date-based schedule, a work order will be generated every month with the schedule date for the work unit as the 10^th of that month.

Date-based schedules can be of two types:

Fixed Interval - The execution of a work unit is repeated irrespective of the completion of its previous execution. For example, consider a task with a fixed interval schedule repeated in a 30 days interval. The schedule date for the task will be forecasted after the completion of every 30 days, irrespective of whether the previous execution of the task was completed or not.
Floating Interval - The execution of a work unit depends on the status of its previous completion. In the above example, if the task is due to be executed on March 10, then the schedule would not execute the task until its previous execution is completed. If the task is completed on March 18, then the system will execute the task next on April 18..

Usage Based Schedule:

Usage-based schedules are defined based on the usage of the maintainable entity. Since consumption parameters quantify asset usage, usage based schedules are based on the consumption parameters of the entity. The schedule for the next performance of a maintenance activity will be specified in terms of the value for the consumption parameter. For example, if the work unit must be performed after every 1000 flight hours, then a work order will be generated after every 1000 flight hours run by the aircraft. Multiple parameters can be defined with different intervals.

Usage-based schedules can be of two types:

Fixed Interval - The execution of a work unit is repeated irrespective of the completion of its previous execution. For example, consider a task with a fixed interval schedule repeated every 1000 flight hours. The schedule date for the task will be forecasted after the completion of every 100 flight hours, irrespective of whether the previous execution of the task was completed or not.
Floating Interval - The execution of a work unit depends on the status of its previous completion. In the above example, if the task due to be repeated after the first 1000 flight hours is not completed, then the schedule would not execute the task until its previous execution is completed.

What you can do in this page

Specify the schedule type for the execution of the work unit

Specify the mode for calculating next due dates for the work units

Specify the schedule type for the execution of the work unit

Set the “Schedule Type” field to “One Time” if the work unit must be performed only once.
Set the “Schedule Type” field to “Recurring” if the work unit must be performed repeatedly at certain intervals.

Specify the mode for calculating next due dates for the work units

Set the “Update Basis” field to “Schedule” if the next due dates for carrying out the work units must be calculated based on a fixed interval.
Set the “Update Basis” field to “Actual Completion”, if the next due dates for carrying out the work units must be calculated based on its previous completion.