Aircraft corrosion and crack inspection using advanced magneto-optic imaging technology

A next generation magnetooptic imaging system, the MOI 303, has recently been introduced with the ability to generate real-time, complete, two-dimensional eddy current images of cracks and corrosion in aircraft. The new imaging system described features advanced, digital remote control operation and on-screen display of setup parameters for ease of use. This instrument gives the inspector the capability to more rapidly scan large surfaces areas. The magneto-optic/eddy current imaging technology has already been formally approved for inspection of surface cracking on an aircraft fuselage. The improved magnetooptic imager is now poised to aid rapid inspection for corrosion and subsurface cracking. Previous magnetooptic imaging systems required the inspector to scan the surface twice for complete inspection coverage: a second scan was necessary with the imager rotated about 90 degrees from the orientation of the first pass. However, by providing eddy current excitation simultaneously from two orthogonal directions, complete, filled-in magneto-optic images are now generated regardless of the orientation of the imager. These images am considerably easier to interpret and evaluate. In addition, there is a synergism obtained in applying eddy current excitation simultaneously in multiple directions: better penetration is obtained and the resulting images have better signal to noise levels compared to those produced with eddy current excitation applied only in one direction. Examples of these improved images are presented.