Maintainability Repair Information
To calculate maintainability measures for your system, you must supply the repair information to use for each repairable component. The following table defines the various terms used in maintainability predictions. Once repair information for components is supplied, maintainability results can easily be calculated.
Component
Description
Reference
Task
A single step taken in the repair of a failed component. For example, removing a screw is a task. The tasks and the times to perform them are stored in Maintainability Task Library files. A Maintainability Task Library file for the tasks in MIL-HDBK-472 (MIL-HDBK-472 Tasks.RTK) is supplied.
Task group
A collection of tasks that are performed together as a maintenance action in the repair of a failed component. For example, the following tasks for replacing a video card might be collected together in a task group:
1. Screw, Remove.
2. Video Card, Remove.
3. Video Card, Replace.
4. Screw, Replace.
Task groups are also stored in Maintainability Task Library files. Any task in a Maintainability Task Library file can be inserted in a task group.
Fault detection and isolation (FD&I) output
An output that is associated with tasks or task groups and acts as an indicator for when they should be performed. An FD&I output can be a visual or audio indication, symptom, printout, readout, or the result of a manual procedure. For example, an FD&I output for a computer might be poor or no display on the monitor due to a bad video card. The tasks or task groups associated with isolating and replacing the bad video card would be associated with this output. In other cases, tasks or task groups may be for detecting a failure and then determining which components or assemblies must be repaired or replaced. The tasks or task groups to perform when an FD&I output occurs are stored in Maintainability FD&I Library files. When entering information for a repairable assembly or part, you have the option of selecting a repair definition from enabled Maintainability Tasks or FD&I Library files.
Maintainability group
When using MIL-HDBK-472 Procedure 5A, you must specify maintainability groups. The Project’s Maintainability Groups file stores the maintainability groups to use for MIL-HDBK-472 Procedure 5A.
Maintainability data
Information about the particular design that is being analyzed must include a listing of replaceable items with their associated part numbers, reference designators, and failure rates. The tasks, task groups, or FD&I outputs associated with each replaceable item are also necessary. Information about the design of the system is stored in the System Tree of the System file. For each replaceable item, tasks, task groups, or FD&I outputs are specified in the Maintainability Data pane.