Introduction Following recent developments in renewable energy sources, wind turbines have been one of the main devices that have been focused on. Basically, wind turbines are devices that convert the kinetic energy of the wind into electrical energy for human use. “Wind farms” are created in very windy places to harness this energy. However, it is impossible to exploit the full energy potential of the wind. Only 59% of the total kinetic energy of the wind flowing through the turbine can be harnessed. Efficiency largely depends on the maintenance of the wind turbine and its components. A variety of tests can be applied to test material and structures. Extensive analysis and NDT testing performed. The life cycle of wind turbines, the blades are a very important component. Equipment durability due to rotation and exposure to the surrounding environment causes thermal stress, corrosion, oxidation and erosion. These aspects reduce the lifespan of the wind turbine. Lifespan may vary based on usage, due to many unexpected accidents that occur in the blade environment. Furthermore, some types of manufacturing or repair can deteriorate components and at the same time reduce the life of the modules. PENETRATING DYE TESTING Penetrant dye testing is the NDT method most often used to inspect wind turbine blades and fins. It is recommended to use fluorescent penetrating dyes for the examination. After a certain period of overhaul, the blade surface is often corroded. Under these circumstances, fluorescent dye penetrant is not approved, and normal dye penetrant is more practical. The disadvantage of the penetrating dye test is its suitability only for cracks opening on the surface. Subsurface defects cannot be detected. As soon as a crack is found, it is not possible to estimate the systems destroyed. In addition to indicating defect depth, ET is also likely to provide better sensitivity and therefore more timely guidance for life assessment of uncoated components compared to inspections based on surface techniques alone. Sensor limitations have delayed parallel developments in UT, but the obstacles do not appear insurmountable. CONCLUSION There are many methods available to determine the properties of turbine blades. Some of these methods can be used to supplement the information received from dye penetrant testing. Most methods are only available in the laboratory phase. But there are some techniques, such as eddy current and ultrasonic techniques, that can be used in practical on-site inspections. The driving force behind the NDT assessment is obviously the need for utilities to optimize plant operation and minimize the risks of damage to the service.