The present project focuses on the failure analysis of high pressure gas turbine compressor blades in Hesa power plant. Five cases of premature failures happened in high pressure section of the compressor in Hesa power plant, three of which happened in the 9 th , one in the 10 th , and one in the 12 th stage of compressor. Since the latest failures happened in the 9 th row, and more information was available about them, the project focuses on the 9 th stage of compressor with Ti-6Al-4V blades. Fracture surfaces, cracked blade, different parts of the blade alloy, and also the disk alloy were metallurgically investigated. Chemical analysis, tensile test, hardness test, optical and electron microscopy and fractography analysis were performed on the samples. Also considering the steady working condition of the compressor, the stresses due to centrifugal forces in the dovetail of the blade and the disk were analyzed using numerical finite element method, and the stress distribution was studied. Fretting fatigue seems to be the dominant mechanism in the failure of the compressor blades. This mechanism is dominant when the two surfaces have very limited (less than 50 micron) relative movement, and undergo alternating loads. In order to become more familiar with this mechanism, its different characteristics, specifically fretting fatigue of Ti alloys, have been explained in the second chapter of this report. It seems that one of the main effective factors on the increasing the sever localized stress in the dovetail of blade and sever wear in this region is unsuitable overhaul of compressor and the lack of enough gap and distance in dovetail of the blade and disk, leading the root of blade to undergo more stresses during the service. In addition, the soft coating increases friction coefficient which leads to severe wear in the blade root and disk. This situation has led the fretting fatigue mechanism to be activated rapidly in this blade. According to the studies performed by different turbine producing companies such as Pratt Whitney in Canada, in addition to the need to control the installation of the blades on the disk, and also providing required equipments to carefully control the compressor’s bleeding valves, two suggestions have been offered to increase the resistance of Ti blades to fretting fatigue, which are as follows: Using suitable surfacing process and coating on the blades (such as sand blasting and using DLC or plasma nitration coatings), application of compression stresses (such as Low plasticity burnishing, LPB), or both.