Wind turbines are gaining importance in the last years because of their high efficiency during energy production without greenhouse gas emission. Furthermore, they can be installed both on-and off-shore. However, wind blade maintenance operations have become difficult and expensive due basically to size aspects and operative costs related with their location and out-off service period. A non-destructive technique capable of detecting most significant in service defects in composite wind blade is infrared thermography (IRT). However, this method can only be applied by developing cost efficient in situ inspection strategies. This work presents a feasibility study for defect detection during maintenance operations in wind blades using unmanned aerial systems (UASs). IRT inspections are performed by means of passive IRT methodology first (i) for specimen located at the ground level with artificial defects (like delaminations, cracks, impact damage and debondings) and later (ii) during flight operation using an rotorcraft UAS. The developed inspection strategies, test results and several features of the developed acquisition system are reported.

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The usage of metal Additive Manufactured (AM) components is growing in aerospace industry since the establishment of quality standards and due to the current maturity of the manufacturing systems, processing route, and inspection methodology. Moreover, possibilities of designing complex shapes by using 3D-printers enables design engineers to build lightweight structures and/or increase part functionality. However, the freedom in design is often a challenge for non-destructive testing (NDT), especially in parts with limited access, non-flat surfaces, etc. Therefore, there are few NDT methods which can be applied on such complex 3D geometries and capable of inspecting the whole part volume. Computed Tomography (CT) and Digital Xray methods are the most relevant ones offering rich information of inner defectology and the outer geometrical metrology. Simulation tools regarding manufacturing process and mechanical behavior are already considered as part of the definition phase of AM components and utilized as inputs in the design loop. However, inspectionability issues are mainly considered during the quality assurance phase. Therefore, inspection problems related with the detectability of defects above the part allowable can appear once the part have been designed, validated, and manufactured. On the other hand, tools that perform numerical simulations of X-ray imaging like SimCT could be a valuable source of additional information [1]. Firstly, for the users of XRay imaging devices in order to set up best inspection parameters and system configuration [2, 3]. Secondly, for producing CT simulations which can evaluate the inspectionability of a part, avoiding non-inspectionable regions limited by the inspection method. In this way, this information can be introduced for validating the part design for instance at PDR (Preliminary Design Review) and later at CDR (Critical Design Review) levels. In this work, an aluminum Image Quality Indicator (IQI) with calibrated defects has been analyzed with both real and simulated CT scans using different physical resolutions. In this way, a comprensive analysis for determining the limits of defect detectability by comparing both simultaion and test results has been developed. Defects of 100, 200 and 500µm diameter have been evaluated, corresponding to aerospace allowable for pores in AM hardware, depending on part criticality.

X-Ray Computed Tomography (CT) has been established as the preferable NonDestructive Testing (NDT) method to detect inner defects in Metal Additive Manufactured (MAM) parts such as porosity, inclusions, lack of fusion, etc. Moreover, the usage of this manufacturing technology has grown in the aerospace sector due to the establishment of quality standards and the current maturity of the manufacturing systems, processing route and means of inspection. For instance, the European Cooperation for Space Standardization has developed a specific standard (coordinated by the European Space Agency – ESA) for AM quality assurance, processing, and requirements in space applications (ECSS-Q-ST-70-80C) indicating that CT inspections shall be carried out especially for critical structural and functional components. Similarly, large OEMs (Original Equipment Manufacturers) have developed their own standards considering CT as a mandatory NDT method in critical parts, but also other techniques such as Penetrant Testing (PT), Digital Radiography (DR) or visual inspection (VI) are also considered necessary to assure the quality of the components. This works presents diverse applications examples of different NDTs for hardware qualification: Titanium brackets for CHEOPS space missions; Aluminium helix antenna for PROBA3; Aluminium brackets for JUpiter ICy moons Explorer mission (JUICE), the last; or other aeronautic components like Aluminium fairings for the Clean Sky 2 IADP demonstrator, and structural Titanium flap fittings of the RACER helicopter. The aforementioned cases will be analysed not only from the execution of the inspection, but also from the application of different standards and requirements, specifically developed for AM or adapted to this novel manufacturing technology.