Thadd C. Patton
David K. Hsu
FAA-Ctr. for Aviation Systems Reliability, Iowa State Univ., Ames, IA 50011
In keeping with the requirements of the air carrier maintenance community, a closed-cycle, water-coupled, focused-beam ultrasonic method for the NDI of adhesively bonded aircraft fuselage structures has been developed. This approach, known as the ``dripless bubbler'' technique is the combination of focused-beam immersion ultrasonics with protable ultrasonic scanners. Because a focused ultrasonic beam is used during the scan, the spatial resolution is much greater than that obtainable with conventional flat contact transducers. The improved spatial resolution is necessary for the detection of localized corrosion pits and surface roughness associated with active corrosion sites in aluminum skin structures. The dripless bubbler allows for the capability to ultrasonically scan the exterior of an aircraft over surface protrusions such as button-head rivets in any orientation without the problem of uncontained couplant water. Recently the dripless bubbler has been involved in a technology deployment and transition program as part of the FAA-National Aging Aircraft Research Program. The result of this technology transfer will be a fully functional prototype scanner incorporating the dripless bubbler technique for rapid, large area NDI of aircraft bonded structures. Results will be presented on the development history of the dripless bubbler along with its current design and verification process. [Work supported by FAA.]