Inspection of Helicopter Rotor Blades by Neutron- and X-ray Radiography

In order to detect the presence of defects in the composite structure of helicopter rotor blades, combined neutronand X-ray radiography investigations were performed at the Budapest Research Reactor. The rotor blades were about 10 m (or 6,5 m) long, and therefore the images were taken in several segments, and a special program was developed to reconstruct the entire radiographic image from the individual segments. Several types of defects were discovered using neutron radiation: imperfections in the honeycomb structure, resin-rich or resin-starved areas at the core-honeycomb surfaces, in-homogeneities in the adhesive filling, corrosion products behind the covering, and water percolation at the sealing interfaces of the honeycomb sections. The location and condition of structural metal parts was analysed by X-ray radiography.