{"id":9748,"date":"2022-03-08T00:00:00","date_gmt":"2022-03-08T00:00:00","guid":{"rendered":"https:\/\/websitemigration.xyz\/what-is-fault-tree-analysis-fta\/"},"modified":"2024-09-20T03:11:33","modified_gmt":"2024-09-20T07:11:33","slug":"what-is-fault-tree-analysis-fta","status":"publish","type":"post","link":"https:\/\/eptura.com\/discover-more\/blog\/what-is-fault-tree-analysis-fta\/","title":{"rendered":"What is fault tree analysis (FTA)?"},"content":{"rendered":"

Before you can make any progress to avoid future failures, you have to first work your way back to discover the root causes. Otherwise, it’s not a question of if a failure can reappear; it’s just a question of when.<\/span>\u00a0<\/span><\/p>\n

Fault tree analysis (FTA) is a systematic method that helps you diagram lower-level events to understand how a system can fail so you can find ways to reduce risks.<\/span>\u00a0<\/span><\/p>\n

What is fault tree analysis?<\/span>\u00a0<\/span><\/h2>\n

Fault tree analysis is closely connected to root causes analysis and shares the goal of helping you understand systems specifically in terms of how they can fail. In many cases, it can help you understand how specific combinations of events can come together to create failures.<\/span>\u00a0<\/span><\/p>\n

A quick review of root cause analysis makes it easier to understand FTA.<\/span>\u00a0<\/span><\/p>\n

In the basic Five Whys process of root cause analysis, you start with a failed state and keep asking yourself why until you reach the root cause. Generally, but not always, you need to ask five times, with each answer creating the basis of the following question. So, if the failed state is that the engine won’t start, you ask yourself why. The answer is that the battery is dead. So, the next question is “Why is the battery dead?” If the answer to that is a broken alternator, you then ask, “What’s wrong with the alternator?” Eventually, you might arrive at “Because the maintenance department missed the PM to check the alternator.”<\/span>\u00a0<\/span><\/p>\n

FTA is similar because you’re also starting at an undesired state, so it’s possible to use the same example, the engine won’t start. But instead of asking questions, we’re creating a diagram with all the possible reasons for the failure. Throughout the diagram, we include events and gates. Events represent things that can happen in the system that either directly cause or partially contribute to a failure. Gates are show how failure moves through the system. At any given gate, you might need only one event for the failure to move to the next level. In some, you might need a combination of events to all happen before the failure can pass through the gate and spread further, while in others you need only some of the related events.<\/span>\u00a0<\/span><\/p>\n

Because of the relationships between gates and events, you can understand the gates as operating on Boolean logic.<\/span>\u00a0<\/span><\/p>\n

Common FTA events<\/span>\u00a0<\/span><\/h3>\n

At the top of your diagram is the top event (TE), the event that you want to figure out how to avoid. It’s the failure that’s at the center of your analysis, but because you’re using a tree diagram, it’s at the top. Basic events (BE) are along the bottom of the tree. Although\u00a0they can move up, passing gates to connect with other events, there’s nothing below them. Between the two are your intermediate events (IE), which are first caused by the BEs before the move up to in turn cause the TE.<\/span>\u00a0<\/span><\/p>\n

Common FTA gates<\/span>\u00a0<\/span><\/h3>\n

For an AND gate, the failure can only pass if all the input events happen. The number of inputs is not important; it might be two or two hundred. But for them to pass the gate, they all need to happen. With an OR gate, you need one or more of the events to happen before they can pass, while with XOR, you need only one of them. If more than one event happens, they can’t pass.\u00a0\u00a0<\/span>\u00a0<\/span><\/p>\n

What are the benefits of FTA?<\/span>\u00a0<\/span><\/h2>\n

One way to understand the benefits is to look at the origins. In the early 60s, Bell Laboratories developed FTA to ensure the safety and reliability of the Intercontinental Ballistic Missile (ICBM) Launch Control System. From there, it quickly spread to other high-hazard industries, including:<\/span>\u00a0<\/span><\/p>\n