Root Cause Failure Analysis - Trinath Sahoo

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       Experience builds your capability to handle future major failures – When a major failure does occur, your “rusty” employees and your out of date processes simply won’t be able to handle it. Both the military and healthcare managers have proven that the more often you train for and work through actual major failures, the better prepared you will be when an unplanned failure occurs in the future.

      Many companies and organizations have been on the reliability journey for a number of years. There are many elements of a solid reliability program – establishing a reliability‐centered culture, tracking key metrics, bad actor elimination programs and establishing equipment reliability plans – to name a few. But, one key element to a solid reliability program, and one that is very important to improving unit reliability metrics, is root cause failure analysis (RCFA). One of the interesting benefits of organizations that have fully embraced the RCFA work process across the entire organization is that over time the RCFA methodology starts to impact how people approach everyday problems – it becomes how they think about even the smallest failure, problems, or defects. Now the organization starts to evolve into a culture that does not accept failure and provides a mindset to help eliminate failures across the organization.

      It is not uncommon to see industries caught in the vicious cycle of failure, repair, blame, failure, repair, blame, etc. When there is premature failure of equipment, people involved often asked the question, whose fault it is. Many a time you will get the answer “it is other guy’s fault.”

      If one were to ask a operator why the equipment fail, the immediate answer will be it was the fault of maintenance mechanic who had not fixed it properly. In the same line, a maintenance mechanic likely answer to that question would be “operator error.” At times, there is some validity to both these answers, but the honest and complete answer is much more complex. This chapter briefly introduces the concepts of failure analysis, root cause analysis, and the role of failure analysis as a general engineering tool for enhancing failure prevention.

      Failure analysis is a process that is performed in order to determine the causes that may have attributed to the loss of functionality. These defects may come from a deficient design, poor material, mistakes in manufacturing or wrong operation and maintenance. Many a time there is no single cause and no single train of events that lead to a failure. Rather, there are factors that combine at a particular time to allow a failure to occur. Failure analysis involves a logical sequence of steps that lead the investigator through identifying the root causes of faults or problems.

      Look at any well‐studied major disaster and ask if there was only one cause. Was there only one cause for the TITANIC? Three Mile Island? The Exxon Valdez mess? Bhopal? Chernobyl? It would be nice if there were only one cause per failure, because correcting the problem would then be easy. However, in reality, there are multiple causes to every equipment failure. Let us take the case of TITANIC failure.

      The two official investigations back in 1912 started with a conclusion – the TITANIC hit an iceberg and sank. They made somewhat of an attempt to answer why that happened without attaching too much blame. The result was not so much as getting to the root cause but found out the immediate cause.

      Richard Corfield writes in a Physics World retrospective on the disaster that caused 1514 deaths on 14–15 April 1912. He described it was an event cascade followed by a perfect storm of circumstances conspired the TITANIC to fail. The iceberg that the TITANIC struck on its way from Southampton to New York is No. 1 on a top‐9 list of circumstances. Here are eight other suggested circumstances from Richard Corfield's article and other sources:

       Climate caused more icebergs: Weather conditions in the North Atlantic were particularly conducive for corralling icebergs at the intersection of the Labrador Current and the Gulf Stream, due to warmer‐than‐usual waters in the Gulf Stream. As a result, there were icebergs and sea ice concentrated in the very position where the collision happened

       The iron rivets were too weak: Metallurgists Tim Foecke and Jennifer Hooper McCarty looked into the materials used for the building of the TITANIC at its Belfast shipyard and found that the steel plates toward the bow and the stern were held together with low‐grade iron rivets. Those rivets may have been used because higher‐grade rivets were in short supply, or because the better rivets couldn’t be inserted in those areas using the shipyard's crane‐mounted hydraulic equipment. The metallurgists said those low‐grade rivets would have ripped apart more easily during the collision, causing the ship to sink more quickly that it would have if stronger rivets had been used.

       The ship was going too fast: Many investigators have said that the ship’s captain, Edward J. Smith, was aiming to better the crossing time of the Olympic, the TITANIC’s older sibling in the White Star fleet. For some, the fact that the TITANIC was sailing full speed ahead despite concerns about icebergs was Smith’s biggest misstep. “Simply put, TITANIC was traveling way too fast in an area known to contain ice, which was one of the major reason of the TITANIC disaster.

       Iceberg warnings went unheeded: The TITANIC received multiple warnings about icefields in the North Atlantic over the wireless, but Corfield notes that the last and most specific warning was not passed along by senior radio operator Jack Phillips to Captain Smith, apparently because it didn't carry the prefix “MSG” (Masters’ Service Gram). That would have required a personal acknowledgment from the captain. “Phillips interpreted it as non‐urgent and returned to sending passenger messages to the receiver on shore at Cape Race, Newfoundland, before it went out of range,” Corfield writes.

       The binoculars were locked up: Corfield also says binoculars that could have been used by lookouts on the night of the collision were locked up aboard the ship – and the key was held by David Blair, an officer who was bumped from the crew before the ship’s departure from Southampton. Some historians have speculated that the fatal iceberg might have been spotted earlier if the binoculars were in use, but others say it wouldn’t have made a difference.

       The steersman took a wrong turn: Did the TITANIC’s steersman turn the ship toward the iceberg, dooming the ship? That’s the claim made by Louise Patten, who said the story was passed down from her grandfather, the most senior ship officer to survive the disaster. After the iceberg was spotted, the command was issued to turn “hard a starboard,” but as the command was passed down the line, it was misinterpreted as meaning “make the ship turn right” rather than “push the tiller right to make the ship head left,” Patten said. She said the error was quickly discovered, but not quickly enough to avert the collision. She also speculated that if the ship had stopped where it was hit, seawater would not have pushed into one interior compartment after another as it did, and the ship might not have sunk as quickly.

       Reverse thrust reduced the ship's maneuverability: Just before impact, first officer William McMaster Murdoch is said to have telegraphed the engine room to put the ship's engines into reverse. That would cause the left and right propeller to turn backward, but because of the configuration of the stern, the central propeller could only be

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