Improved Ultrasonic Scanner. Part 2. Field Evaluation.

Abstract : One of the most challenging problems for the aerospace NDE community in recent years has been the nondestructive inspection for radial cracks, around installed fasteners, in first layer aircraft wing structure. A few years back, Boeing proposed a technique which used ultrasonics to perform such an inspection. This method used a water-filled rubber boot attached to the transducer face to couple the sound waves into the inspection surface. The angle of incidence and the radial distance of the point of incidence could be varied manually. This instrument, however, has a very limited field use. Using the above concept, SRL developed a semiautomatic microprocessor-based NDE system-Autoscan, which allows for convenient adjustment for optimum inspection parameters. Four such instruments were manufactured and used for inspection of the Air Force SIEP C-5A wing at Lockheed-Georgia. Since that time, these units have been used to inspect many other USAF aircraft. This paper discusses the results of the field evaluation of Autoscan in detection of radial bolt hole cracks in C-5A and aircraft wing structure in general.