Related Topics and Links:
	Tasks Corrective Tasks Preventive Tasks Inspection Tasks On Condition Tasks

Corrective Tasks

Corrective maintenance consists of the action(s) taken to restore a failed component to operational status. Corrective maintenance is performed at unpredictable intervals because a component's failure time is not known a priori.

Corrective tasks:

• Always bring the block down.

• May bring the system down.

• Require spare parts.

In addition to the common task properties, the following options are used to configure corrective tasks in the Maintenance Task window:

• Task Scheduling allows you to specify when the corrective task will be performed.

• • If you choose Upon item failure, the task will be initiated upon failure of the component.

  • If you choose When found failed during an inspection, the task will be initiated if the component is found to be failed at the next scheduled inspection. This is useful in the case of "hidden failures" (i.e., failures that are not apparent until an inspection is performed) and in cases where the component is not considered mission critical and repair can wait until the next scheduled maintenance.

  • • If a preventive task takes place before the next inspection, then preventive maintenance (not corrective maintenance) will be performed to restore the block. The downtime, etc. will depend on the preventive task properties.

    • If a corrective task is performed upon inspection and an inspection finds the block failed, then the total downtime includes the full inspection duration followed by the corrective task duration.

If you have selected to perform a corrective task upon inspection and an inspection or preventive task does not occur after the failure, then the block will never be restored. This could happen under either of the following circumstances:

1. 1. • Neither an inspection nor a preventive task is specified for the block.

and/or

• 1. • The conditions have not been met to perform an inspection or preventive task.

• Basic Repair Properties > Spare Part Pool allows you to choose or create a spare part pool that will be used in performing the task. If a spare part pool is not assigned, it is assumed that unlimited free spares are always immediately available.

For corrective and preventive tasks, the simulation requests a crew as soon as a task is initiated; however, the crew does not begin performing the task unless/until the spare part is available.

The total time for the task consists of:

1. • The time to complete corrective and preventive maintenance (based on the corrective task or preventive task properties).

PLUS

1. • The longer of the following times:

   • • The time to obtain the spare part (based on the spare part pool).

OR

1. 1. • The time to obtain an available crew (based on crew availability) and any logistical delay time associated with the crew.

For example, if the block fails at 10 hours (on the system clock), the corrective task will take 5 hours, the time required to obtain the spare will be 48 hours and the logistical delay time associated with the crew is 8 hours, then:

1. • The spare will arrive at 58 hours (on the system clock).

   • The crew will be requested at 10 hours and will arrive at 18 hours (on the system clock).

   • The maintenance will be completed at 63 hours (on the system clock).

   • The total time for the corrective maintenance will be 53 hours (48 for the spare plus 5 for the task).

   • The crew will have traveled for 8 hours, waited 40 hours for the spare part and performed the task for 5 hours for a total of 53 hours (including waiting for the spare part).

If the spare part is available without delay and all other conditions are the same, then:

• • The crew will be requested at 10 hours and will arrive at 18 hours (on the system clock).

  • The maintenance will be completed at 23 hours (on the system clock).

  • The total time for the corrective maintenance will be 13 hours (8 for the crew plus 5 for the task).

  • The crew will have traveled for 8 hours and performed the task for 5 hours for a total of 13 hours.

• Task Consequences

• • Does this task bring the system down?: By default, corrective tasks will not bring the system down unless having the block down brings the system down based on the reliability-wise configuration in the diagram. If you answer Yes, the task will bring the system down even if the task has a zero duration. This forces the task to be included in the count of system downing events, regardless of the task's duration.

  • Does this task bring the item down?: It is assumed that a block will always be down when a corrective task is performed, even a task with a zero duration; thus, this option cannot be changed.

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