In this thesis, assess electromechanical components of hydropower plant condition by usingrnfault tree analysis. Show the failure occurrences of Gilgel gibe II hydropower plantrngeneration units.rnAlso developed and constructed the model of fault tree of electromechanical components ofrnhydropower plant system based on Gilgel Gibe II hydropower plant in Ethiopia.rnThe causes are deductively identified as the event causing every possible hazard byrnconstructing a fault tree. The fault tree is constructed in a hierarchical structure with a singlerntop event. The qualitative results help in focusing attention on main apparatus ofrnelectromechanical components that contributed to the unreliability of the system. Throughrnqualitative fault tree analysis of electromechanical components Disabled turbine sub-systemrncontain 26 single-basic-event minimal cut sets with occurrence probabilities 0.026; thisrnindicates that disabled turbine sub-system is the highest ranking in qualitative structurernimportance which means the disabled turbine sub-system is the weakness point in thernelectromechanical system. The Turbine generator unit failure sub-system contain 14 singlernbasic events and 12 two basic events of minimal cut sets with occurrence probabilitiesrn0.014012, this indicates that The Turbine generator unit failure subsystem is the strongestrnpoint of electromechanical system.rnQuantitative analysis is performed to estimate the probability of the top event occurrence andrnsub top event occurrences or unreliability of the electromechanical components hydropowerrnplant system. The quantitative fault tree analysis resulted the rankings of quantitativerncontribution of sub-systems to the occurrence of top event are obtained as Disabled Turbinernwith occurrences of 0.0256776, Malfunction Generator with occurrences of 0.0158806 andrnTurbine-Generator unit failure with occurrences of 0.0139212 respectively. This means thatrnutmost care should be taken to prevent the occurrence of the most contribute sub-system ofrnelectromechanical system failure. Turbine Failure is the most contribute sub-system ofrnelectromechanical system failure, so it takes care to prevent the electromechanical system.rnAnd finally propose maintenance policy for the common component or system failurern(cooling and lubrication system) under root causes.rnKeywords: Fault tree analysis, electromechanical components of hydro power plantrn(Turbine, Generator and Governor and Control system)