Abstract: Methods and apparatuses for detecting corrosion in one or more blades of a gas turbine system includes a detection head having a shape that conforms to a surface geometry of a filet section of a gas turbine blade, whereby the detection head is operable to move along the axial length of the filet section for detecting corrosion pitting. At least one coil device located within the detection head induces a first magnetic field within an area of the filet in contact with the detection head. A receiver device is adapted to detect a signal corresponding to a second magnetic field received from the area of the filet exposed to the first magnetic field, where the second magnetic field is generated by induced currents in the area by the first magnetic field.