Large-Standoff, Large-Area Thermography (LASLAT)
Nondestructive testing has played a central role in the long-running struggle against aviation accidents. In the 1990s, technicians used dye penetrant inspection and magnetic-particle and fluorescent-particle methods to detect fine cracks in engine components, a step up from trying to spot cracks with a borescope or the naked eye. It was these methods that would be lumped together under the name “non-destructive inspection” (NDI).
Of course, aircraft contain a wider range of materials—and possess more points of failure—than can be found in their engines. One concern for modern technicians is “disbonds” in composite material, often found in external components and/or covering large surfaces. Disbonds occur when layers of a composite material separate, diminishing its integrity and resistance to cracking and other serious types of damage.
As Aviation Week describes, traditional inspection methods have their drawbacks:
One simple method of detecting disbonds is the “coin tap” in which the material is gently struck with a metal object and the inspector listens for a telltale dull thud. Helicopters have been equipped with composite blades for decades, and coin tapping them has shown that method’s efficacy to be extremely subjective, influenced by both the environment and the inspector’s perceptiveness.
More recently, thermography, also called thermal imaging, has showed considerable value as a technological solution for the non-destructive inspection of composites, though its usefulness for inspecting large areas has been limited by reliance on gantry systems and the design of scanning apparatuses. However, in the past few years, NCMS member Thermal Wave Imaging pioneered a system that overcomes these restrictions.
Thermal Wave Imaging won last year’s CTMA Technology Competition with its Large-Standoff, Large-Area Thermography (LASLAT) system, an NDI solution capable of inspecting a 17-by-15-foot area with a stationary device placed 15 feet back from the aircraft being inspected. LASLAT systems are now in production, with the first unit now in use by Fleet Readiness Center (FRC) East to inspect proprotor blades on the V-22 Osprey tiltrotor aircraft. Thermal Wave Imaging also presented on LASLAT at this year’s CTMA/DLA Partners Meeting at DLA Distribution Richmond, where Maglogix won the 2018 CTMA Technology Competition.
You can read more about LASLAT and the CTMA Technology Competition in the 20th-anniversary edition of CTMA Magazine.