Root Cause Failure Analysis. Trinath Sahoo

a problem. This is critical as symptoms often mask the causes of problems. As with effective incident classification, basing actions on symptoms is worst possible practice. Using the technique effectively will define the root cause of any non‐conformances and subsequently lead you to defining effective long‐term corrective actions.

      While you want clear and concise answers, you want to avoid answers that are too simple and overlook important details. Typically, the answer to the first “why” should prompt another “why” and the answer to the second “why” will prompt another and so on; hence the name Five Whys. This technique can help you to quickly determine the root cause of a problem. It's simple and easy to learn and apply.

      The 5‐Why analysis is the primary tool used to determine the root cause of any problem. It is documented in the Toyota Business Process manual and practiced by all associates.

      When to Use 5 Why

      When the problem and root cause is not immediately apparent When you want to prevent the problem from occurring in the future.

      Ask yourself, “Will implementing the Systemic Corrective Action prevent the next failure?” If the answer is “NO,” you must understand the deeper WHY.

      If human error is identified, you must understand why the human committed the error. What management controlled factor impacted performance? What system must change to eliminate (or significantly reduce) the chance for error? “Training the Operator” is rarely the best response.

Why was the operator not trained properly? Why was the training not effective? What environmental factors caused the operator to not do his/her best work? Did he/she have to go around the system due to other issues or pressures? Can the system be error‐proofed? All root cause analysis must include a look at the associated Management Systems For virtually every incident, some improvement(s) in the Management Systems could have prevented most (or all) of the contributing events – ASQ estimates 82–86% Correct the process that created the problems.

      During the 5 Why analysis, you should ask yourself if there are similar situations that need to be evaluated perform a “Look Across” the organization. If this situation could apply to multiple funds, then the corrective action must address all funds.

      How to Use the 5 Whys

      1 Develops the problem statement. Be clear and specific.

      2 Assemble a team of people knowledgeable about the processes and systems involved in the problem being discussed. They should have personal knowledge about the non‐conformance of the system.

      3 On a flip chart, presentation board, or even paper; write out a description of what you know about the problem. Try to document the Problem and describe it as completely as possible. Refine the definition with the team. Come to an agreement on the definition of the Problem at hand.

      4 The team facilitator asks why the problem happened and records the team response. To determine if the response is the root cause of the problem, the facilitator asks the team to consider “If the most recent response were corrected, is it likely the problem would recur?” If the answer is yes, it is likely this is a contributing factor, not a root cause.If the answer provided is a contributing factor to the problem, the team keeps asking “Why?” until there is agreement from the team that the root cause has been identified.It often takes three to Five Whys, but it can take more than five! So keep going until the team agrees the root cause has been identified.

      The 5 Whys can help you uncover root causes quickly. However, making a single mistake in any question or answer can produce false or misleading results. You may find that there is more than one root cause for each non‐conformance; corrective actions should be implemented for each of these.

Fishbone Diagram

      One of the more popular tools used in root cause analysis is the fishbone diagram, otherwise known as the Ishikawa diagram, named after Kaoru Ishikawa, who developed it in the 1960s. A fishbone diagram is perhaps the easiest tool in the family of cause and effect diagrams that engineers and scientists use in unearthing factors that lead to an undesirable outcome.

A fishbone diagram is a visual way to look at cause and effect. It is a more structured approach than some other tools available for brainstorming causes of a problem (e.g., the Five Whys tool). The problem or effect is displayed at the head or mouth of the fish. Possible contributing causes are listed on the smaller “bones” under various cause categories. A fishbone diagram can be helpful in identifying possible causes for a problem that might not otherwise be considered by directing the team to look at the categories and think of alternative causes. Include team members who have personal knowledge of the processes and systems involved in the problem or event to be investigated.

      Fishbone Diagram Structure

      The left side of the diagram is where the causes are listed. The causes are broken out into major cause categories. The causes you identify will be placed in the appropriate cause categories as you build the diagram.

      The right side of the diagram lists the effect. The effect is written as the problem statement for which you are trying to identify the causes.

      Ishikawa Fish Bone Diagram

      The diagram looks like the skeleton of a fish, which is where the fishbone name comes from.

      How to Create a Cause and Effect Diagram

      A cause and effect diagram can be created in six steps.

      1 Draw Problem Statement

      2 Draw Major Cause Categories

      3 Brainstorm Causes

      4 Categorize Causes

      5 Determine Deeper Causes

      6 Identify Root Causes

      1 Draw Problem StatementThe first step of any problem‐solving activity is to define the problem. You want to make sure that you define the problem correctly and that everyone agrees on the problem statement.Once your problem statement is ready, write it in the box on the right‐hand side of the diagram.

      2  Draw Major Cause CategoriesAfter the problem statement has been placed on the diagram, draw the major cause categories on the left‐hand side and connect them to the “backbone” of the fishbone chart.In a manufacturing environment, the traditional categories areMachines/EquipmentMethodsMaterialsPeopleIn a service organization, the traditional categories are…PoliciesProceduresPlantPeopleYou can start with those categories or use a different set that is more applicable for your problem. There isn't a perfect set or specified number of categories. Use what makes sense for your problem.Cause and Effect Diagram ‐ Major Cause Categories

      3 Brainstorm CausesBrainstorming the causes of the problem is where most of the effort in creating your Ishikawa diagram takes place.Some people prefer to generate a list of causes before the previous steps in order to allow ideas to flow without being constrained by the major cause categories.However, sometimes the major cause categories can be used as catalysts to generate ideas. This is especially helpful when the flow of ideas starts to slow down.

      4  Categorize CausesOnce your list of causes has been generated, you can start to place them in the appropriate category on the diagram.Draw a box around each category label and use a diagonal line to form a branch connecting the box to the spine.Write the main categories your team has selected to the left of the effect box, some above the spine and some below it.Ideally, each cause should only be placed in one category. However, some of the “People” causes may belong in multiple categories. For example, Lack of Training may be a legitimate cause for incorrect usage of Machinery as well as ignorance about a specific Method.Establish the major causes, or