FMECA and FMEA
The FMECA Module of Reliability Workbench provides the full framework and reporting facilities to allow users to construct FMECAs to MIL-STD-1629A, BS 5760 Part 5, GJB 1391-92, AIAG FMEA 3, SAE J1739, ARP5580 and similar standards as well as customizing the FMECA to the user’s own requirements.
In addition Process and Design FMEAs and commercial aircraft FMEAs may also be constructed and analyzed within this module. EFA (European Fighter Aircraft) format FMECAs may also be constructed.
What is FMECA? What is FMEA?
A Failure Mode, Effects and Criticality Analysis is a procedure for identifying potential failure modes in a system and classifying them according to their severity values.
A FMECA is usually carried out progressively in two parts:
- Identifying failure modes and their effects (Failure Mode and Effects Analysis).
- Ranking failure modes according to the combination of severity and the probability of that failure mode occurring (Criticality Analysis).
How do I Construct a FMECA?
The FMECA procedure may be summarized as completing the following steps:
- Define the system to be analyzed
- Construct a hierarchical block diagram
- Identify failure modes at all levels of indenture
- Assign effects to the failure modes
- Assign severity categories to effects
- Enter other failure mode data such as failure detection methods, failure rates, etc.
- Rank failure modes in terms of severity and criticality
- Produce reports highlighting critical failures
- Recommend redesign or maintenance actions to reduce critical failures
The FMECA Module provides interactive graphical facilities for constructing a block diagram representing the logical connection between the sub-systems and components constituting the overall plant or system. This diagram may be extended to represent failure modes at various hierarchical levels.
The FMECA Module permits the rapid entry of data using pop-up dialogs which may be accessed simply by clicking on the relevant part of the block diagram.
Automatic Calculation in FMECA
One of the most powerful features of the FMECA Module is its ability to automatically trace failure effects, severity values and failure causes through the system hierarchy. Failure rate and criticality values are automatically calculated by the program.
The FMECA Module will also filter detectable and non-detectable failures in reports and determine the ratio between the frequency of detectable failures and total failures.
A large proportion of data entered when performing a FMECA is descriptive text. The FMECA Module provides a master phrase library which contains commonly used descriptions of component parts, failure modes and effects. These phrases may be inserted into descriptive fields by selecting the required phrase from the library saving considerable typing and ensuring consistency.
Users may build up their own phrase libraries or add to the master library provided.
The FMECA Module provides an apportionment library facility which allows the user to create commonly used component and failure mode groupings. Each failure mode in a grouping is given an apportionment percentage. Users may add a component to the FMECA block diagram together with the appropriate failure modes by selecting the appropriate entry in the apportionment library. This saves considerable effort when constructing the block diagram.
Process and Design FMEA
Process and Design FMEAs provide an alternative approach to performing a Failure Mode and Effect Analysis. Occurrence, severity and detection rankings replace apportionments and failure rates. Risk Priority Numbers (RPN) are calculated by multiplying the severity, occurrence and detection ranking numbers together.
Commercial Aircraft FMEA
Commercial Aircraft FMEAs are a special format of FMEA allowing users to define failure modes and effects at unit, system, engine and aircraft level.
Some of the FMECA Module features are summarized below :
- Apportionment library for fast data entry
- Phrase library for eliminating repetitive text entry
- User-definable data fields
- Effects automatically traced through to system level
- Root contributors automatically calculated
- Extensive sorting facilities
- Data verification for consistency checks
- Severities automatically assigned
- Automatic criticality calculations
- Multiple failure effects permitted for a single failure mode
- Effects may be defined on any higher-level sub-system
- User-definable severity category libraries
- Failure detection filter facility
- Sub-projects may be linked to a master project
- Automatic data transfer from prediction modules
- Drag and drop components to the RBD module
- Spelling checker and global text replacement
- Automatic fault tree construction facility