Introduction Failure mode and effects analysis

1 introduction

1.1 functional analysis
1.2 ground rules
1.3 benefits

introduction

the fme(c)a design tool used systematically analyze postulated component failures , identify resultant effects on system operations. analysis characterized consisting of 2 sub-analyses, first being failure modes , effects analysis (fmea), , second, criticality analysis (ca). successful development of fmea requires analyst include significant failure modes each contributing element or part in system. fmeas can performed @ system, subsystem, assembly, subassembly or part level. fmeca should living document during development of hardware design. should scheduled , completed concurrently design. if completed in timely manner, fmeca can guide design decisions. usefulness of fmeca design tool , in decision-making process dependent on effectiveness , timeliness design problems identified. timeliness important consideration. in extreme case, fmeca of little value design decision process if analysis performed after hardware built. while fmeca identifies part failure modes, primary benefit identification of critical , catastrophic subsystem or system failure modes can eliminated or minimized through design modification @ earliest point in development effort; therefore, fmeca should performed @ system level preliminary design information available , extended lower levels detail design progresses.

remark: more complete scenario modelling type of reliability analysis may considered, example fault tree analysis (fta); deductive (backward logic) failure analysis may handle multiple failures within item and/or external item including maintenance , logistics. starts @ higher functional / system level. fta may use basic failure mode fmea records or effect summary 1 of inputs (the basic events). interface hazard analysis, human error analysis , others may added completion in scenario modelling.

functional analysis

the analysis may performed @ functional level until design has matured sufficiently identify specific hardware perform functions; analysis should extended hardware level. when performing hardware level fmeca, interfacing hardware considered operating within specification. in addition, each part failure postulated considered failure in system (i.e., single failure analysis). in addition fmeas done on systems evaluate impact lower level failures have on system operation, several other fmeas done. special attention paid interfaces between systems , in fact @ functional interfaces. purpose of these fmeas assure irreversible physical and/or functional damage not propagated across interface result of failures in 1 of interfacing units. these analyses done piece part level circuits directly interface other units. fmea can accomplished without ca, ca requires fmea has identified system level critical failures. when both steps done, total process called fmeca.

ground rules

the ground rules of each fmea include set of project selected procedures; assumptions on analysis based; hardware has been included , excluded analysis , rationale exclusions. ground rules describe indenture level of analysis, basic hardware status, , criteria system , mission success. every effort should made define ground rules before fmea begins; however, ground rules may expanded , clarified analysis proceeds. typical set of ground rules (assumptions) follows:

benefits

major benefits derived implemented fmeca effort follows:

from above list, identifications of sfps, input troubleshooting procedure , locating of performance monitoring / fault detection devices important benefits of fmeca. in addition, fmeca procedures straightforward , allow orderly evaluation of design.