Determination of Functional Failures

DOE-STD-1052-93

Component reliability problems that do not have human performance factors may best

be resolved by using the functional analysis technique commonly used in reliability-

centered maintenance programs. The functional analysis technique, as applied to

components, is described in Sections 6.5, "Determination of Functional Failures"; and

6.6, "Determination of Failure Modes and Effects."

The functional analysis technique establishes the following:

component functions

component failure modes

effects or consequences of the failures

It should be recognized that analysis of component performance problems usually

results in addition of PM activities. It also should be noted that the results of the

component analysis may be modified when the system containing the component is

analyzed. Documentation developed during the component analysis should be

retained and available for use in the system analysis, described in Section 7.

6.5

Determination of Functional Failures

This section describes the method for determining component functions and how the

component may fail.

From the data collected during the component history review, the functions of the

component should be determined and recorded. Functions are actions or

requirements the component should accomplish to support its overall system function.

It is important that all functions of the component be identified since preserving these

functions is the primary objective of the PM tasks that should be selected.

After the component functions are determined, the next step is to identify the likely

failures that may cause loss of one or more component functions. These are called

functional failures. A functional failure exists when a component ceases to provide

a required function whether the function is active or passive, evident or hidden. Some

functional failures may be considered to be implausible. Examples of implausible

failures are those that result from a rare or unexpected external occurrence or from

an unexpected or unlikely failure mechanism. Although they are noted, implausible

failures are not considered for further analysis.

D - 13