Importance analysis of fault trees by visual inspection

To achieve high reliability for any system, it is necessary to identify the components and the subsystems that have the greatest impact on its reliability. Such items can be identified using importance measures that rank the items quantitatively according to their contribution to the system unreliability. Taking into consideration the complexity and time involved in computing these measures we have proposed an algorithm that can pinpoint the most important component just by visually inspecting the fault tree. Calculations whenever required, involve simple arithmetic. It gives the user freedom from the complex calculations, save their time and performs the intended task without the use of software tools. Then the generalization of this work has been proposed that ranks the components of the fault tree. We have illustrated both the algorithms for the fault trees without as well as with repeated events.