FMECA Module Basics

FMECA grid in the lower part of the screen appears after the FMECA module activation.

It displays Failure Modes and its consequences for the currently selected product tree element.

To perform the FMECA analysis, you should define Failure Modes for each product tree element.

Then for each Failure Mode its conditional probability (Alpha) and possible consequences chain should be defined: Next Higher Effects, their Next Higher Effects and End Effects.

Each item may have multiple Failure Modes, each Failure Mode may have multiple Next Higher Effects, each Next Higher Effect may have multiple End Effects.

On the illustration below, Failure Mode of Hard Drive (Single sector data error) cause NHE (Next Higher Effects) of System block (Error in data processing), which in turn lead to NHE of Control unit (Wrong system control) which in turn lead to several EE (End Effects) of the whole system level:

FMECA_Illustration

The RAM Commander FMECA module screenshot below displays FM-NHE-EE chains for the same situation explained above (TUTORIAL project):

FMECA_HDDSample

Each failure mode may have multiple detection methods (selected from FMECA Tests library). Each detection method may have Efficiency factor (probability of failure detection) from 0 to 1:

FMECA_Tests

Failures without detection methods considered to be undetectable (latent) failures.

Additional information (remarks, compensating provisions, corrective actions, user-defined fields etc.) may also be defined for each Failure Mode.

See below descriptions of standard FMECA data table fields:

Field	Description (MIL-STD-1629)
Failure Mode	The manner by which a failure is observed. Generally describes the way the failure occurs and its impact on equipment operation.
Failure Cause	The physical or chemical processes, design defects, quality defects, part misapplication, or other processes which are the basic reason for failure or which initiate the physical process by which deterioration proceeds to failure.
Alpha, Failure Mode Ratio	Failure mode conditional probability. The fraction of the part failure rate (FR) related to the particular failure mode under consideration shall be evaluated by the analyst and recorded. The failure mode ratio is the probability expressed as a decimal fraction that the part or item will fail in the identified mode. If all potential failure modes of a particular part or item are listed, the sum of the Alpha values for that part or item will equal one.
Next Higher Assembly (NHA)	Assembly/product tree item related to the Next Higher Effect
Next Higher Effect (NHE)	The consequence(s) a failure mode has on the operation, functions, or status of the items in the next higher indenture level above the indenture level under consideration.
Beta	Failure Effect probability Beta - conditional probability that the failure effect will result in the identified criticality classification, given that the failure mode occurs
End Effect	The consequence(s) a failure mode has on the operation, function, or status of the highest indenture level.
Detection	The means or methods by which a failure can be discovered by an operator under normal system operation or can be discovered by the maintenance crew by some diagnostic action.
Severity	The consequences of a failure mode. Severity considers the worst potential consequence of a failure, determined by the degree of injury, property damage, or system damage that could ultimately occur.
Corrective Action	A documented design, process, procedure, or materials change implemented and validated to correct the cause of failure or design deficiency.
Compensating Provisions	Actions that are available or can be taken by an operator to negate or mitigate the effect of a failure on a system.