Maintainability Prediction Lab

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Maintainability Prediction Lab Last revised
02/09/2011
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Introduction
This lab will walk the user through the steps
involved in performing a Maintainability
Prediction using ASENT. For this lab we will use
the product tree that was created as part of the
Failure Rate Prediction lab exercise. Please
complete this exercise before proceeding with the
Maintainability lab.
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Section 1 Creating A Project Scenario
This lab will leverage off of the product tree
structure that was created in the Failure Rate
Prediction lab. The first thing we will do is
enter the Maintainability Manager and define the
active scenario. Once this is complete then we
will import the product tree structure that was
used for the reliability prediction. The slides
that follow will guide you through these steps.
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Invoking the Maintainability Manager
From ASENTs Session Manager the Maintainbility
tool is invoked by right-clicking on the class
project and selecting the Maintainability Manager
option.
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Create New FRP Scenario
To create a new Maintainability scenario, fill in
the information as shown in this example, then
click on the Save button. You can have multiple
What-if scenarios for each project. These are
helpful for performing trade-offs. To create
other scenarios use the File New options.
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Import Reliability Product Tree
A good starting point for our Maintainability
analysis is to import the product tree from our
reliability prediction. We can then add any
covers or additional hardware later. Right-click
on the project node and select the Import
Reliability options. Click the OK button and
click Yes to overwrite the tree.
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Section 2 Editing the Maintainability Tree
The next thing we will do is add covers, access
panels, or other hardware that is normally
excluded from the reliability prediction. ASENTs
Maintainability Manager gives you full tree
editing The slides that follow will guide you
through the steps of adding new items to your
product tree for the Maintainability Analysis.
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Adding an Access Panel Step 1
We are going to add an access panel to our tree
structure that will be associated with the
subsys1 subassembly. Click on the symbols to
expand the tree structure and then right-click on
subsys1 and select the Add option from the
drop-down menu.
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Adding an Access Panel Step 2
Fill in the data, as shown, then click on the
Save button. Here, we are adding an access panel
to our Maintainability product tree.
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Access Panel is Added
This screen shows the new access panel that was
just added when you clicked on the Save button.
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Detailed Task Information
Once your product tree structure has been edited
for your analysis you are now ready to manage the
detailed task information associated with each
item. This includes tasks associated with Fault
Detection and Isolation, and items that must be
Disassembled or Reassembled to reach the item of
interest, Remove and Replace Tasks,
Alignment/Adjustment tasks, and Verification
Tasks. You can also enter Judgments for cautions,
notes, or as difficulty factors for working in
cramped or adverse conditions.
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Detailed Task Information
ASENTs Maintainability Manager is used to manage
the scenario tree, its corresponding tasks and
any Maintainability predictions associated with
it. It references tasks and task groups from the
Maintainability library. The Maintainability Data
Manager is the tool in ASENT where you define new
tasks, or task groups, and tools in your library.
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Section 3 Managing Your Maintainability Library
Two task libraries are pre-populated in ASENT
COMMON_M472 and COMMON_RADC. The COMMON_M472
library contains all of the tasks and task times
associated with Mil-Hdbk-472. The COMMON_RADC
library contains all of the tasks and task times
associated with RADC-TR-84-165. You can define
task categories and tasks or task groups for any
project that you are assigned to. A yellow folder
next to a project indicates that you have editing
privileges on that project.
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Adding a Maintenance Task Step 1
We are going to add a maintenance task to the FRP
library. Since this library does not have any
categories you will need to add one. Click on the
symbols to expand the tree structure and then
right-click on the FRP project and select the
Add Category option from the drop-down menu.
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Adding a Maintenance Task Step 2
Enter cat1 for the task category and click on
the Save button.
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Adding a Maintenance Task Step 3
Now that a category exists we can add a
maintenance task. There are two types of tasks.
The Remove/Replace task is used specifically
for tasks associated with removing and replacing
items. Other tasks are used for any other
situations. Right-click on cat1 and select the
Add Task Add Remove/Replace Task options.
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Adding a Maintenance Task Step 4
Enter the information for the task as shown and
click on the Save button.
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Task Groups
Maintenance Task Groups represent a set of
maintenance tasks. For example, you may define an
Engine Repair as a Task Group, and it would list
all of the tasks associated with an engine
repair. The slides that follow will walk you
through the creation of a task group.
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Adding a Task Group Step 1
To define a task group, click on the Task
Groups tab and click on the symbol to expand
the Task Groups tree. Right-click on your project
and select the Add option.
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Adding a Task Group Step 2
Fill in the information as shown, and click on
the Save button.
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Adding a Task Group Step 3
Click on your newly created task group then click
on the Task Group Tasks tab. Right-click on the
name field grid and select the Add option from
the menu. The select task window appears. Expand
the task tree in order to select tasks.
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Adding a Task Group Step 4
The Select Task window allows you to navigate to
any task library that you want to and select
tasks to be added to your task group. Select a
task and click OK and it will be added to the
task group. Click OK once you have selected 5
tasks in a similar fashion.
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Adding a Task Group Step 5
You can enter skill codes if you like. These are
free-form fields. In our example the A represents
Avionics, and E represents Electrical, but you
can use whatever you like. You can also edit the
Quantity and Number of People associated with
each task. The second screen shot shows the
display when you click on the Task Group tab.
Here it shows you the information associated with
the Task Group for all of its tasks.
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Section 4 Tasks, Task Groups, Judgments
Detailed tasks and judgments can be associated
for each item in your scenario tree. The
Maintainability Manager allows you to easily
reference tasks and task groups from the library,
and define judgments for cautions, notes, or as
difficulty factors for working in cramped or
adverse conditions. The slides that follow
provide examples of this.
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Defining Tasks Step 1
Select the Access Panel and click on the
button next to the Remove Time Field. The Edit
Remove Tasks window appears.
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Defining Tasks Step 2
The Edit Remove Tasks option allows you to select
tasks and task groups from the library, and
define judgments. Right-click on the grid and
select the Add Task All option. The Select a
Task window then appears so that you can select a
maintenance task from the library. These tasks
are maintained by the Maintainability Data
Manager. Here, you are selecting maintenance
tasks from the library.
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Defining Tasks Step 3
Select the symbol to expand the tree and open
up the FASTENERS folder under the COMMON_M472
project library. Select the M-001 Standard
Screw, Fastener and click on the OK button.
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Defining Tasks Step 4
The task appears in the Edit Remove Tasks grid.
Here, you can modify the of People needed to
perform the task, enter skill codes, and modify
the quantity. You can also enter a more
descriptive explanation of this task in the
Narrative field.
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Defining Task Groups - Step 1
We have now entered a maintenance task associated
with the Access Panel. Next, we will enter a task
group. Right-click on the first row in the grid
and select the Add Task Group option. Select Task
Group 1 from the Select Task Groups list and
click on the OK button.
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Defining Task Groups - Step 2
Task Group 1 now appears in the Edit Remove Tasks
window. Here, you can enter skill codes or adjust
the quantity information if desired.
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Defining Judgments - Step 1
Judgments have many uses. They can be used to
create a warning, caution, or note for the
maintainer, or they can be used as a difficulty
factor to add additional time for working in
cramped or adverse conditions. They can be
associated with a specific task, or be
non-specific and generally applicable for the
item you are repairing.
Right-click on the second row of the Edit Remove
Tasks grid and select the Add Judgement
Non-Task Specific Judgement options.
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Defining Judgments - Step 2
A non-task specific judgment appears in the Edit
Remove Tasks window. Here, we add 2.0 minutes and
document in the Narrative field the reason. Click
the OK button.
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Section 5 Defining Replace Tasks
Normally, the tasks performed to replace or
install an item are essentially the same as the
tasks used to remove the item (only in the
opposite order). The slides that follow provide a
shortcut for accomplishing this.
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Defining Replace Tasks - Step 1
Notice that the Remove Time value now reflects
the time associated with the Remove Tasks that we
defined earlier. To define Replace Tasks
associated with the Access Panel, click on the
button next to the Replace Time
field.
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Defining Replace Tasks - Step 2
Right-click on the first row in the grid and
select the Default to Inverse of Remove Items
option, and click on the Yes button when the
confirmation window appears.
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Defining Replace Tasks - Step 3
Notice, that the remove tasks appear in the
reverse order, with their corresponding
replacement times. You can use the Up Down
arrows to reposition the tasks if necessary, and
add any additional tasks that may be required.
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Section 7 Copying Tasks
Follow the same steps that you learned earlier,
and add the two remove tasks shown below for
board1. The slides that follow will show you how
to copy tasks from one item in your scenario tree
to another.
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Copying Tasks - Step 1
ASENT allows you to easily copy tasks from one
item in your Scenario Tree to another. Right-click
on board1 and select the Copy Node Data option.
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Copying Tasks - Step 2
To paste tasks from board1 to board2, right-click
on board2 and select the Paste Node Data
option. The Select Fields to Copy window will
then appear, and give you the option of
deselecting some of the fields, if desired. Click
on the OK button, and then click Yes when the
confirmation window appears.
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Section 7 Disassembly/Reassembly Items
Disassembly/Reassembly Items account for the
items that must be moved out of the way in order
to reach the item of interest. Covers and Access
Panels are good examples of these. Another
example might be where a mother board has other
cards plugged into it. These cards would be
considered disassembly/reassembly items if we
were changing out the mother board. The slides
that follow provide examples of working with
disassembly/reassembly items and their associated
access and close-up tasks.
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Defining Disassembly Items - Step 1
Disassembly items represents items that must be
moved out of the way to get to the item of
interest. To specify disassembly items associated
with board1, click on the button next to
the Disassembly Time field. Additional Access
tasks may also be needed. Click on the second
button next to Disassembly Time to
enter these.
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Defining Disassembly Items - Step 2
In this example, the Access Panel needs to be
removed to get to board1, so it would be
considered a disassembly item associated with
board1. Click on the Access Panel and then select
the button with an arrow pointing to the
right. This will move it into your list of
selected items. Click on the OK button.
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Defining Reassembly Items - Step 1
Notice, that the Disassembly Time is now
populated to reflect the fact that the Access
Panel is a disassembly item. Now, lets define
Reassembly items for board1. Click on the
button next to the Reassembly Time
field. Additional Close Up tasks may also be
needed. Click on the second button next
to Reassembly Time to enter these.
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Defining Reassembly Items - Step 2
Normally, items that we have to move out of the
way to reach an item need to be put back once the
repair is complete. In most cases the reassembly
items are just the disassembly items in the
reverse order. Right-click on the Access Panel
and select the Default to Inverse of Disassembly
option. Click on the Yes button when the
confirmation window appears.
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Defining Reassembly Items - Step 3
The Access Panel moves over into the Selected
Items list. Click on the OK button. The
Reassembly Time is now filled in for board1.
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Section 8 Creating a Maintainability Prediction
You have now successfully defined detailed task
data for some of the items in your scenario tree.
We will utilize this information in a simple
maintainability prediction. The slides that
follow provide examples.
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Maintainability Predictions - Step 1
Previously we had been working in the Scenario
Tree. To create a prediction, click on the
Predictions tab.
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Maintainability Predictions - Step 2
Modify the Prediction defaults as shown here, and
click on the Save button.
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Maintainability Predictions - Step 3
To create a new prediction using the defaults
that you selected, right-click on the Predictions
item and select the Add option.
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Maintainability Predictions - Step 4
For this example, click on the OK button.
When adding a new maintainability prediction, you
have a lot of flexibility to control what is
automatically brought in from the scenario tree.
The default option will bring in all items from
the scenario tree, but you can choose to bring in
only items marked with a certain assembly type
(e.g. LRU) or with certain SMR Codes. If the Add
individually option is selected nothing will be
brought into the prediction, but from the
prediction you can add items one at a time or
select multiple items to be brought in. Selecting
the Cancel button aborts the creation of the
prediction.
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Maintainability Predictions - Step 5
Enter I Level for the Prediction Name and click
on the Save button.
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Maintainability Predictions - Step 6
Click on the Corrective Maintenance tab to
refine your prediction information. Here, you can
add or delete items, and user-set values to
perform quick trade-offs. When you uncheck a
user-set value then it will revert back to the
calculated value if detailed task information
exists for the item.
By clicking on the splitter bar, the right side
of the screen will become full screen. If you
click it again then it will go back to the
original layout.
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Maintainability Predictions - Step 7
You can see prediction results at a glance by
clicking on the Prediction Results tab.
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Section 9 Generating Reports
You can generate reports from both the Scenario
tree or the Predictions view. All of the reports
generate a familiar Excel spreadsheet format. The
slides that follow provide examples.
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Maintainability Reports - Step 1
Right-click on your prediction and select the
Reports Procedure 2 Prediction options.
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Maintainability Reports - Step 2
It is not uncommon to see this confirmation
window when you run a report. If any values in
your prediction have been user-set or defaulted
then they will not match the details in your
scenario tree, and in this case you would get
this warning message. Click No to acknowledge the
message, but dont worry about having it update
the prediction prior to the report. We are
receiving the message because we defaulted some
of the prediction values.
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Maintainability Reports - Step 3
Click the OK button to generate the report. A
sample Procedure II Prediction report is shown
below.