ARM 55: 2) Root Cause Analysis

Steps in root cause analysis process

The RCA process is a systematic way to determine root cause. The steps include data collection, casual factor charting, root cause identification, and recommendation determination and implementation.

Casual factors

The agents that directly result in one event causing another.

End effect

The consequence of a failure mode on the operation, function, or status of the highest indenture level.

Next-higher-level effect

The consequence of a failure mode on the operation, function, or status of the items in the indenture level immediately above the indenture level under analysis.

Local effect

The consequence of a failure mode on the operation, function, or status of the specific item or system level under analysis.

Root cause

The event or circumstance that directly leads to an occurrence

Failure mode

The manner in which a perceived or actual effect in an item, process, or design occurs.

Risk priority number (RPN)

The product of rankings for consequence, occurrence, and detection used to identify critical failure modes when assessing risk within a design or process.

Effects analysis

The study of a failures consequences to determine a risk events root cause(s).

Procedure for conducting a 5 why's analysis

1. The specific problem under investigation is described completely. 2. The investigator asks why that particular problem occurred and determines the answer. 3. If the answer does not reveal the problems root cause, the investigator determines why the problem embodied by the determination made in step two occurred. 4. The investigator repeats the previous two steps until the root cause of the original problem has been determined.

5 whys

5 why's analysis is a crucial component of a fishbone diagrams construction. It is a specific root cause analysis technique used primarily for problems involving human factors, such as managerial oversight. When the problem has been identified, asking why repeatedly can lead to a determination of it's ultimate cause. Prevents investigators from relying on assumptions about the root cause of a problem, and instead traces the problem through a chain of causality to it's origin.

Fishbone diagram

5 why's analysis is the most prevalent method used to fuel the brainstorming sessions that generate specific causes depicted in a fishbone diagram. These causes are depicted as diagonal lines (fish's bones) connected to a horizontal arrow (fish's spine) that indicates the problem being addressed.

Criticality

A combination of the risk priority number elements of consequence and occurrence used to determine the relative risk of a a failure mode and effects analysis item.

M's alternatives

A simplified version of 4 m's only uses the categories of machine, method, materials and manpower. 8 m's adds the categories of management/money power and maintenance.

Root cause analysis (RCA)

A systematic procedure that uses the results of the other analysis techniques to identify the predominant cause of the accident.

8 p's

Also used by organizations in the service industry as an alternative to 8 m's: product or service, price, place, promotion/entertainment, people (key person), process, physical evidence, productivity and quality.

5 s's

Also used by organizations in the service industry as an alternative to 8 m's: surroundings, suppliers, systems, skills, and safety.

Criticality analysis

An analysis that identifies the critical components of a system and ranks the severity of losing each component.

Failure mode and effect analysis (FMEA)

An analysis that reverses he direction of reasoning in fault tree analysis by starting with causes and branching out to consequences.

Fault tree analysis (FTA)

An analysis that takes a particular system failure and traces the events leading to the system failure backwards in time.

Indenture level

An items relative complexity within an assembly, system, or function.

6 m's

This group of categories typically is used to determine root causes of problems in manufacturing. •machine (technology) - any equipment or technology involved in completing a job, such as computers, tools, or other machinery •method (process) - requirements that specify how a process is performed (for example, policies, procedures, rules, regulations and so forth) •materials - information, parts, pens, papers, raw materials, and so forth used to make the final product (consumables) •manpower (physical work)/mind power (brain work) - anyone involved in a process who provides physical or mental effort •measurement (inspection) - data generated from a process used to judge the quality of a product •milieu/Mother Nature (environment) - local conditions, such as temperature, time, location, or culture, within which a process operates

"5 whys" analysis and the fishbone diagram

When used with a 5 why's analysis, a fishbone diagram also can reveal relationships among the variables in a process or system.