ABSTRACT
In the aerospace industry, NDT has fundamental role. Aircraft components are inspected before they are assembled into the aircraft and then they are periodically inspected throughout their useful life. Aircraft parts are designed to be as light as possible while still performing their intended function. Since aircraft are cycled (loaded and unloaded) as they fly, land, take off, and pressurize the cabin, many components are prone to fatigue cracking after some length of time. Over 80 per cent of the inspections done to an aircraft are visual inspections. At regular intervals, inspectors look at various components of the aircraft for signs of damage. However, not all areas of the aircraft can be accessed for visual inspection and not all damage can be detected by visual means. This is where NDT plays a critical role in thoroughly inspecting airplanes [1]. The airplane component object of study in this paper is called slat track: it is the movable support structure that connects the wing with the leading-edge slats. The methodology proposed in this article is a combination of ultrasonic and optical detection, always subject of interest for non-destructive testing (see [2] for an introduction to several NDT techniques). The choice to use an ultrasonic-optical technique instead of other
methods currently used in practice (ultrasonic scanning, magnetic particle inspections, X ray imaging and in general all imaging techniques) is due to following reasons:
• The purpose to use these results for future applications in an on line monitoring of fatigue cracks in aircraft components, when there is not space available for a receiver ultrasound transducer because, during a lab test, the surface moves in contrast with fixed rollers. Using the laser, more ever, a scan over the region of interest can be effectuated.
