Visual inspection with endoscope plays an important role in modern fault diagnosing of aeronautic engine. An inspection approach of aperture’s surface crack on an aeroengine labyrinth disc is studied based on industrial videoscope. The appearance reason of the crack and its characteristic are analyzed firstly. An automatic recognition method of surface crack is proposed based on a localization-recognition model. A novel fuzzy fast Hough transform is presented and used to detect the circular contour to locate the aperture. Then

an interesting region is defined around the aperture

in which the image is binarized by a threshold and the binary image is thinned by a morphological method. Moreover

the chain codes in the image are analyzed to recognize the crack. The results of circular contour detection by the proposed fuzzy fast Hough Transform are compared with the results by Standard Hough Transform and Randomized Hough Transform respectively. The results show that the fuzzy fast Hough transform can detect the contour quickly and accurately. The test of crack detection is carried out in 80 aperture images

and the results indicate that the detecting accuracy is 91.2%.