The Apollo Root Cause Analysis method is a very effective approach to finding effective solutions to event-based problems.
Stated simply, the steps of the Apollo method are:
- Clearly define the problem
- Create a cause and effect chart to explain why the problem occurred
- Identify effective solutions that will prevent the problem from reoccurring (or the likelihood of a reoccurrence represents an acceptable risk)
- Implement and track the best solutions to assure they are effective
An open mind is a key requirement of the Apollo Root Cause Analysis methodology. Preconceived ideas, limitations, and narrow-minded thinking are perhaps the greatest barriers to creative solutions. However, from time to time, a mandate from management can prevent an investigation team from delivering the desired results. Here we’ll examine one example of how a company directive negatively impacted an RCA investigation.
In this company, mixers are used to make a product. They are driven by standard three-phase, AC motors, which will fail with time. The mixers are located in a very congested area and are repaired in place. The motors are accessed from above, but the motor power terminations are on the bottom. As a result, maintenance personnel have to disconnect and reconnect the power leads by feel.
Adding to the challenges of replacing a motor, there is a 50% chance that the new motor will rotate in the wrong direction. Correcting this problem is straight forward – just swap any two of the power leads. The problem is that running the mixer in reverse will damage the mixer internals and the current method to test the motor rotation is to power it up. Even though maintenance personnel try to start and stop the motor as quickly as they can, they are forced to do this at the motor’s main breaker. By the time they turn the breaker off the mixer internals have been damaged. If the motor is running in reverse, maintenance has to swap two of the electrical leads and repair the mixer before it can be returned to service.
A RAM Analysis of the production equipment identified extended downtime after mixer motor replacement as a significant contributor to reduced production capacity. A Root Cause Analysis team was formed to investigate the problem.
The site’s process control system was very antiquated, and an upgrade project would cost around $200,000. The site’s management made it clear that upgrading the process control system was too expensive and they did not want to hear any discussion on the subject. As a result, the RCA investigation team avoided any possible connection to the process control system during their problem analysis.
The investigation team, after interviewing personnel familiar with the problem, but biased by the message they received from site management, summarized the problem as:
“Mixer internals are sometimes damaged after a mixer motor is replaced because the mixer is operated in reverse during post-maintenance work testing. Although the electrician turns the motor on and off as quickly as possible, the motor can generate sufficient speed to damage the internals if the motor is operating in reverse. Because the electricians cannot see the electrical leads, it is guesswork as to whether the electrical leads are installed correctly or not. There is nothing we can do about the situation and sometimes equipment damage will occur."
If we were to put the above information into a ‘Cause and Effect’ chart:
This does not give us a clear understanding of the event and does not provide a sufficient amount of ‘Causes’ to work with for identifying possible solutions. They suspected they were missing something and engaged ARMS Reliability to help facilitate the Root Cause Analysis.
With the help of ARMS Reliability and the Apollo Root Cause Analysis methodology, the investigation team realized where they should have asked more questions to gain a deeper understanding of the event. They also discovered how the site management’s message to avoid any connection to the process control system was impacting their investigation and limiting their brainstorming capabilities.
The revised cause and effect chart contained over 30 causes:
To generate possible solutions, a question is asked of each cause one at a time: “What could we do to change, control, or eliminate this cause?” All possible solutions are captured without discussion. After this brainstorming step is completed, the solutions are reviewed to determine which of them pass these four criteria:
- The solution prevents the problem from recurring
- The solution is within the organization’s control to be implemented
- The solution is in line with the organization’s goals and objectives
- The solution does not cause other problems
Only possible solutions that pass these criteria are considered for implementation.
|Motor rotation test equipment not purchased||Purchase motor rotation test equipment||Passed||Yes|
|No motor "jog" feature
Reverse operation damages mixer internals
|Install motor jog feature||Passed||Yes|
|Line of sight modification not installed||Install second termination box on top of motor||Passed||No|
|Breaker has mechanical internals||Replace with fast acting breaker||Passed||No|
|1 second to reach full mixer speed||Install variable frequency drive||Passed||No|
|1 second to reach full mixer speed||Install slow-start||Passed||No|
|Wires terminated by "feel"||Make wire ends and termination points matched sets||Passed||No|
|Small termination box||Install larger termination box||Failed||No|
|Line of sight modification not installed||Purchase borescope||Failed||No|
|Line of sight modification not installed||Move termination box to top of motor||Failed||No|
|Reverse operation damages mixer internals||Modify mixer internals||Failed||No|
During this investigation, 11 possible solutions were identified. 7 of the 11 possible solutions passed the acceptance criteria and were evaluated for implementation. 2 of the 7 solutions were deemed to provide the best value to the company and were recommended for implementation.
As it turned out, upgrading the site’s process control system was not identified as a recommended solution. This is because upgrading the process control system would not have changed, controlled or eliminated any of the causes in the cause and effect chart. Even if the process control system was upgraded, a mixer would still be damaged if the motor rotation was in reverse. However, the notion to avoid any connection to the process control system stifled the investigation and affected the analytical thinking skills of the group.
The Apollo Root Cause Analysis method helps an investigation team to develop a deeper understanding of why an event occurred. Company directives, opinions, and similar factors are only included in the cause and effect chart, or the subsequent list of possible solutions, if there is a logical connection to the event being investigated. In addition, creating a comprehensive cause and effect chart will yield possible solutions that were not apparent at the beginning of the investigation. This results in identifying and implementing solutions that will prevent the event from recurring.