ISO 17025 Quality Manual ISO 17025 Quality Manual Template

Wednesday, August 02, 2006

 

4.11 Corrective Action

4.11.2 Cause analysis
Procedures for corrective action must start with root cause analysis.

Cause analysis is the key and sometimes the most difficult part in the corrective action procedure. Often the root cause is not obvious and thus a careful analysis of all potential causes of the problem is required. Potential causes could include customer requirements, the samples, sample specifications, methods and procedures, staff skills and training, consumables, or equipment and its calibration.

Root cause analysis (RCA) is a process designed for use in investigating and categorizing the root causes of events with safety, health, environmental, quality, reliability and production impacts. The term “event” is used to generically identify occurrences that produce or have the potential to produce these types of consequences. Simply stated, RCA is a tool designed to help identify not only what and how an event occurred, but also why it happened. Only when investigators
are able to determine why an event or failure occurred will they be able to specify workable corrective measures that prevent future events of the type observed.
Understanding why an event occurred is the key to developing effective recommendations. Imagine an occurrence during which an operator is instructed to close valve A; instead, the operator closes valve B. The typical investigation
would probably conclude operator error was the cause. This is an accurate description of what happened and how it happened. However, if the analysts
stop here, they have not probed deeply enough to understand the reasons for the mistake. Therefore, they do not know what to do to prevent
it from occurring again. In the case of the operator who turned the wrong valve, we are likely to see recommendations such as retrain the operator on the procedure,
remind all operators to be alert when manipulating valves or emphasize to all personnel
that careful attention to the job should be maintained at all times. Such recommendations do little to prevent future occurrences. Generally, mistakes do not just happen but can be traced to some well-defined causes. In the case of the valve error, we might ask, “Was the procedure confusing? Were the valves clearly labeled?
Was the operator familiar with this particular task?” The answers to these and other questions will help determine why the error took place and what the organization can do to prevent recurrence. In the case of the valve error, example recommendations might include revising the procedure or performing procedure validation to ensure references to valves match the valve labels found in the field. Identifying root causes is the key to preventing similar recurrences. An added benefit of an effective
RCA is that, over time, the root causes identified across the population of occurrences can be used to target major opportunities for improvement. If, for example, a significant number of analyses point to procurement inadequacies, then resources can be focused on improvement of this management system. Trending of root causes allows development of systematic improvements and assessment of the impact of corrective programs.

Although there is substantial debate on the definition of root cause, we use the following:
1. Root causes are specific underlying causes.
2. Root causes are those that can reasonably be identified.
3. Root causes are those management has control to fix.
4. Root causes are those for which effective recommendations for preventing recurrences can be generated.

Root causes are underlying causes. The investigator’s goal should be to identify specific underlying causes. The more specific the investigator can be about why an event occurred, the easier it will be to arrive at recommendations that will prevent
recurrence. Root causes are those that can reasonably be identified. Occurrence investigations must be cost beneficial. It is not practical to keep valuable manpower
occupied indefinitely searching for the root causes of occurrences. Structured RCA helps analysts get the most out of the time they have invested in the investigation.
Root causes are those over which management has control. Analysts should avoid using general cause classifications such as operator error, equipment failure or external factor. Such causes are not specific enough to allow management to make effective changes. Management needs to know exactly why a failure occurred before action can be
taken to prevent recurrence. We must also identify a root cause that management
can influence. Identifying “severe weather” as the root cause of parts not being delivered on time to customers is not appropriate. Severe weather is not controlled by management.

Root causes are those for which effective recommendations can be generated. Recommendations should directly address the root causes identified during the investigation. If the analysts arrive at vague recommendations such as, “Improve adherence to written policies and procedures,” then they probably have not found a basic and specific enough cause and need to expend more effort in the analysis process.

Four Major Steps
The RCA is a four-step process involving the following:
1. Data collection.
2. Causal factor charting.

3. Root cause identification.
4. Recommendation generation and implementation.

Step one—data collection. The first step in the analysis is to gather data. Without complete information and an understanding of the event, the causal factors and root causes associated with the event cannot be identified. The majority of time spent analyzing an event is spent in gathering data. Step two—Causal factor charting. Causal factor charting provides a structure for investigators to organize
and analyze the information gathered during the investigation and identify gaps and deficiencies in knowledge as the investigation progresses. The causal factor chart is simply a sequence diagram with logic tests that describes the events leading up
to an occurrence, plus the conditions surrounding these events.

Preparation of the causal factor chart should begin as soon as investigators start to collect information about the occurrence. They begin with a skeleton chart that is modified as more relevant facts are uncovered. The causal factor chart should
drive the data collection process by identifying data needs. Data collection continues until the investigators are satisfied with the thoroughness of the chart
(and hence are satisfied with the thoroughness of the investigation). When the entire occurrence has been charted out, the investigators are in a good position to identify the major contributors to the incident, called causal factors. Causal factors are those contributors (human errors and component failures) that, if eliminated, would have either prevented the occurrence or reduced its severity.
In many traditional analyses, the most visible causal factor is given all the attention. Rarely, however, is there just one causal factor; events are usually
the result of a combination of contributors. When only one obvious causal factor is addressed, the list of recommendations will likely not be complete.
Consequently, the occurrence may repeat itself because the organization did not learn all that it could from the event. Step three—root cause identification. After all the causal factors have been identified, the investigators begin root cause identification. This step involves the use of a decision diagram called the
Root Cause Map to identify the underlying reason or reasons for each causal factor.
The map structures the reasoning process of the investigators by helping them answer questions about why particular causal factors exist or occurred. The identification of root causes helps the investigator determine the reasons the event occurred so the problems surrounding the occurrence can be addressed. Step four—recommendation generation and implementation. The next step is the generation of recommendations. Following identification of the root causes for a particular causal factor, achievable recommendations for preventing its recurrence are then generated. The root cause analyst is often not responsible for the implementation of recommendations generated by the analysis. However, if the recommendations
are not implemented, the effort expended in performing the analysis is wasted. In addition, the events that triggered the analysis should be expected to recur. Organizations need to ensure that recommendations are tracked to completion.

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