(FMECA) - An extensive but simple method for identifying ways in which an engineered system could fail. The primary goal of FMECA is to develop priorities for corrective action based on estimated risk.
Failure mode, effects and criticality analysis (FMECA) is an extension of failure mode and effects analysis (FMEA). FMEA is a bottom-up, inductive analytical method which may be performed at either the functional or piece-part level. FMECA extends FMEA by including a criticality analysis, which is used to chart the probability of failure modes against the severity of their consequences. The result highlights failure modes with relatively high probability and severity of consequences, allowing remedial effort to be directed where it will produce the greatest value.
The FMECA analysis procedure typically consists of the following logical steps: * Define the system * Define ground rules and assumptions in order to help drive the design * Construct system block diagrams * Identify failure modes (piece part level or functional) * Analyze failure effects/causes * Feed results back into design process * Classify the failure effects by severity * Perform criticality calculations * Rank failure mode criticality * Determine critical items * Feed results back into design process * Identify the means of failure detection, isolation and compensation * Perform maintainability analysis * Document the analysis, summarize uncorrectable design areas, identify special controls necessary to reduce failure risk * Make recommendations * Follow up on corrective action implementation/effectiveness
FMECA may be performed at the functional or piece part level. Functional FMECA considers the effects of failure at the functional block level, such as a power supply or an amplifier. Piece part FMECA considers the effects of individual component failures, such as resistors, transistors, microcircuits, or valves. A piece part FMECA requires far more effort, but is sometimes preferred because it relies more on quantitative data and less an engineering judgment than a functional FMECA. The criticality analysis may be quantitative or qualitative, depending on the availability of supporting part failure data.