ASENT_FMECA.PPT

Failure Mode, Effects, and Criticality Analysis (FMECA)Last revised 08/14/2014

ASENT_FMECA.PPT

Introduction

The FMECA toolkit provides most of the analyses commonly associated with a FMECA analysis. It supports the accomplishment of Task 101 (FMEA) and Task 102 (Criticality Analysis). In addition, you can use the toolkit to perform Testability Analysis and Reliability Centered Maintenance for each failure mode in the system.

ASENT’s FMECA Manager supports functional, hardware, or combined FMECAs, and its methodology allows you to do top-down or bottom-up FMECAs. Assemblies, boards, functions, parts, and signals can be modeled along with related failure modes and effects. The relationship between failure modes and effects and the tree structure are automatically tracked by the toolkit so that updates can easily be made at any time.

ASENT_FMECA.PPT

FMECA Manager Screen Layout

ASENT_FMECA.PPT

FMECA Manager Icons and Menu Bar

ASENT_FMECA.PPT

Recommended Methodology

Hint: refer to the FMECA Manager online help. Refer to the ‘Using the FMECA Manager’ help book.

ASENT_FMECA.PPT

Starting A New FMECA

The FMECA Manager is the tool in ASENT that is used to perform FMECAs. From the ASENT Session Manager, right-click on your project and select the FMECA Manager from the drop-down menu.

The first time that you enter the FMECA Manager for a project it will ask you to select a project to copy libraries from.

This gives you the ability to start your FMECA by leveraging off of FMECA data that may already exist for other projects. This can be very helpful when performing an analysis on equipment that is similar, where a FMECA already exists.

ASENT_FMECA.PPT

Initializing FMECA Libraries

If in doubt, just select the COMMON_FMD97 project. This should be highlighted as the default. This project is empty except it contains part types and their failure mode distributions. This is particularly helpful if you are performing a piece-part level FMECA.

Select what data you want copied from the selected project library to your FMECA project. If in doubt, leave everything checked and click the OK button.

If you want a totally blank library, then uncheck all of the boxes and click the OK button.

User selects the COMMON_FMD97 project to use as their default starting point.

ASENT_FMECA.PPT

Defining A Function/Phase

Next, you will create the function/phase for your FMECA. ASENT allows you to have as many function/phase combinations as you want. These are treated like separate projects within a project.

These are used to keep track of the data associated with different modes of operation. For example, you may have a FLIR with a function of Surveillance Mode. Maybe it has a Daytime phase and a Nighttime phase that need to be analyzed separately.

ASENT_FMECA.PPT

Importing the Reliability Tree

Normally, when performing a FMECA, a good starting point is to import the Reliability tree. Once imported, the user can add or delete items, and modify the data, since you have full tree editing capability in the FMECA. This is important, because often, there will be portions of your system that you may want to model functionally in the FMECA.

In the FMECA tool you can import trees or sub-trees from either the Reliability tree or other FMECA trees. If you import the Reliability tree then the FMECA tree will automatically be linked to it. If later, you have to modify descriptions or reference designator values, modify these in the Reliability tree, and simply use the FMECA Update Links option, from the project node, to make these changes in the FMECA. You can sever the links or re-link tree nodes anytime in the future.

ASENT_FMECA.PPT

Importing the Reliability Tree

To import the Reliability tree, right-click on the project node and select the ‘Import’ option from the drop-down menu. When the Import window appears, select ‘Reliability Manager Trees’ and click the OK button.

ASENT_FMECA.PPT

Importing the Reliability Tree

Next, a list of projects appear. Locate your project name in the list and select it, then click on the OK button.

After the project has been selected, a window will be displayed showing the product tree. Initially, the tree is collapsed and only the project node is shown. Select the project node and click on the OK button.

ASENT_FMECA.PPT

Importing the Reliability Tree

Once you have selected the project node of the Reliability tree and clicked OK, then you will be prompted for some additional data.

First, you will be asked whether or not to overwrite the existing FMECA tree. Answer ‘Yes’ so that the FMECA tree becomes a copy of the Reliability tree. If you answer ‘No’ it will append it off the project node of the FMECA tree.

Next, you will be asked whether or not to import parts. If you are doing a piece-part level FMECA then you should answer ‘Yes’. If not, then select ‘No’.

Finally, if you chose to import parts, then you will be asked whether or not to default the failure modes for each of the parts. ASENT does this by using the Part Type/Failures library, which is built into the FMECA. Normally, if you are importing parts, then you would want the failure modes automatically defaulted for these parts, so answer ‘Yes’ to this prompt.

ASENT_FMECA.PPT

Extensive use of libraries reduces data entry and errors

Data entry and errors are significantly reduced by the extensive use of libraries in the tool.

The FMECA Library Editor contains data tabs to access various types of library data.

Libraries exist for failure modes and effects, signals, part types and their corresponding failure modes, and detection or test codes.

The navigation buttons and their meanings are shown below.

ASENT_FMECA.PPT

Part Types/Failures Library

Here, the default Here, the default failure modes and failure modes and their failure their failure distributions are distributions are displayed for a displayed for a Bipolar Digital Bipolar Digital Microcircuit. The Microcircuit. The user can select user can select either the FMD-97, either the FMD-97, MIL-HDBK-338, MIL-HDBK-338, or their own library or their own library for part type for part type failures. This failures. This feature virtually feature virtually eliminates the need eliminates the need to enter failure to enter failure modes for parts modes for parts when doing a piece-when doing a piece-part level FMECA.part level FMECA.

ASENT_FMECA.PPT

Adding Failure Modes

To add failure modes for an item, right-click on its corresponding FMs container and select the ‘Add’ option from the drop-down menu.

Here, we are adding failure modes for the PWRCNV.

ASENT_FMECA.PPT

Adding Failure Modes

Failure modes can be added by either selecting a failure mode that exists in the library, or it can be added on the fly.

Click here to select a failure mode from the library.

Click here to add a new failure mode on the fly.

ASENT_FMECA.PPT

Adding Failure Modes that exist in the library

This screen shows the user selecting a failure mode from the library. This picklist has an active search capability, so if you start typing, it will immediately jump down to the first failure mode that contains your string.

ASENT_FMECA.PPT

Adding Failure Modes on the fly

When the user is adding failure modes for an item and they select the button, then the following screen appears.

This screen allows the user to enter a failure mode that was not previously defined in the failure mode library. The name field will handle 255 characters. Enter the failure mode in the Name field and click OK. Then, click on the Save button to add the failure mode.

The Description field is normally left blank. Only use it if you need more than 255 characters.

ASENT_FMECA.PPT

Working with Failure Modes

Individual failure modes or groups of failure modes can be copied and moved from one location to another. The CTRL-Drag-and-Drop accomplishes a copy and the Drag-and-Drop accomplishes a move.

Always drop the item to be copied on the next biggest item. For example, individual failure modes should be dropped on a FMs container and entire FMs containers dropped on items.

Hint: Refer to the FMECA Manager online help for detailed instructions on working with failure modes. Refer to the ‘Working with Failure Modes’ help book.

ASENT_FMECA.PPT

Entering Failure Mode Ratios

Failure Mode Ratios should only be entered at the lowest level in the tree structure. For example, if you are doing a piece-part level FMECA, then failure mode ratios should be filled in for each failure mode at the part level. If ASENT was told to default the failure modes for the parts, then this will happen automatically.

If the lowest level in your tree structure is a function or a circuit card, then at this level the failure mode ratios need to be filled in. The failure mode ratios for all of the failure modes associated with intermediate nodes should be left blank. Right-click on the project node and select the ‘Roll-up Failure Mode Ratios’ option to calculate these values.

ASENT_FMECA.PPT

Evenly Distribute Failure Mode Ratios

ASENT has the ability to evenly distribute the failure mode ratios among all of an item’s failure modes.

To do this, merely right-click in the grey area above the Description, and select the ‘Distribute FM Ratios’ option.

ASENT_FMECA.PPT

Defining Next Higher Effects

List of modes at the NHA that have not been selected.

Use these buttons to Add or Remove Next Effects.

The failure mode that we are assigning Next Higher Effects for.

ASENT_FMECA.PPT

FMECA Manager product tree display

Here, the Here, the FMECA FMECA Manager displays Manager displays the product tree the product tree structure for the structure for the Radar / Operating Radar / Operating phase that is phase that is being analyzed. being analyzed. By selecting the By selecting the Failure Mode Failure Mode (FMs) container (FMs) container on the project on the project node the user is node the user is able to view or able to view or edit the system edit the system level (End) level (End) effects.effects.

ASENT_FMECA.PPT

User selects a single effect to analyze

Notice, when the user Notice, when the user selects a single failure selects a single failure mode or effect the data mode or effect the data for that item is for that item is displayed on the right displayed on the right side. Also, the user side. Also, the user can select the Causes can select the Causes tab to view the failure tab to view the failure causes, enter causes, enter compensating compensating provisions, remarks, provisions, remarks, the detection method, the detection method, or perform testability or perform testability analysis. At the RIU or analysis. At the RIU or PWRCNV levels in PWRCNV levels in the tree the user would the tree the user would also be able to view / also be able to view / edit the Next Higher edit the Next Higher Effects.Effects.

ASENT_FMECA.PPT

Viewing the causes of a system level effect

The user views the The user views the failure causes for the failure causes for the highlighted system highlighted system level effect by level effect by clicking on the clicking on the Causes tab. Here, a Causes tab. Here, a bit circuit failure on bit circuit failure on the RIU causes a bit the RIU causes a bit circuit failure on the circuit failure on the system.system.

ASENT_FMECA.PPT

Viewing the End Effects of a Failure Mode

The user can easily The user can easily view all the End view all the End Effects for a failure Effects for a failure mode by selecting the mode by selecting the End Effects Tab. This End Effects Tab. This informs him if the informs him if the Criticality Criticality Calculations are Calculations are current and shows the current and shows the criticality, severity criticality, severity and conditional and conditional probability.probability.

ASENT_FMECA.PPT

Adding & Viewing Graphics

The user can add graphics The user can add graphics or supporting documents to or supporting documents to the tree, or view this the tree, or view this information for an information for an assembly by selecting assembly by selecting ‘Graphics’ from the pop ‘Graphics’ from the pop up menu.up menu.

ASENT_FMECA.PPT

FMECA Manager Menus

Failure rates in the FMECA Failure rates in the FMECA can easily be updated with can easily be updated with new prediction results from new prediction results from the Reliability Manager. The the Reliability Manager. The tool calculates Criticality and tool calculates Criticality and Fault Detection / Isolation. Fault Detection / Isolation. Extensive reporting Extensive reporting capabilities exist, including a capabilities exist, including a user defined report feature.user defined report feature.

ASENT_FMECA.PPT

Built-in Completeness Checker

The Check The Check FMECA utility FMECA utility checks your checks your analysis and analysis and pinpoints any pinpoints any areas where areas where needed data is needed data is missing. This missing. This time saving time saving feature helps feature helps ensure that your ensure that your analysis is analysis is complete. In complete. In spreadsheets and spreadsheets and many other tools many other tools this is usually this is usually performed performed manually by the manually by the user.user.

ASENT_FMECA.PPT

Completeness Checker Results

Here, the completeness Here, the completeness checker reports that the checker reports that the LOSS OF 5 VOLTS A LOSS OF 5 VOLTS A failure mode does not have failure mode does not have a Next Higher Effect, and a Next Higher Effect, and that the Criticality numbers that the Criticality numbers have not been calculated.have not been calculated.

ASENT_FMECA.PPT

Finding Data in the FMECA

The Find menu The Find menu makes it easy to makes it easy to find items within find items within your FMECA. your FMECA.

ASENT_FMECA.PPT

Fault Detection / Isolation

Here, the user Here, the user defines the defines the detection / detection / isolation groups isolation groups to determine test to determine test coverage. For coverage. For example, the example, the SRA TEST SRA TEST group uses test group uses test points to isolate points to isolate failures to the failures to the component level. component level. The Isolation The Isolation Group sizes are Group sizes are defined as <=4, defined as <=4, <=8, and <=10 <=8, and <=10 components.components.

Refer to the Testability Analysis tutorial for more details.

ASENT_FMECA.PPT

Leverage the existing Failure Mode Analysis

The user enters The user enters detection / detection / isolation isolation information at information at the lowest the lowest level, and then level, and then intermediate intermediate values are values are calculated. calculated. Here, an Here, an Improper Improper Config Config Resistor failure Resistor failure is detected by is detected by the SRA TEST the SRA TEST group using group using testpoint J1-92. testpoint J1-92. It isolates the It isolates the failure to the failure to the R0005 R0005 component.component.

ASENT_FMECA.PPT

Importing / Exporting Data

Data from the FMECA Data from the FMECA can easily be exported to can easily be exported to Logan for Fault Tree Logan for Fault Tree Analysis, creating Analysis, creating significant savings of significant savings of time and money in time and money in performing this analysis.performing this analysis.

Failure Mode data may Failure Mode data may also be imported to the also be imported to the library from an Excel library from an Excel spreadsheet.spreadsheet.

In addition, entire In addition, entire FMECAs can be FMECAs can be imported using the imported using the FMECA Import.xls FMECA Import.xls template found in the \template found in the \ASENT\Data folder.ASENT\Data folder.