The extensive use of composite materials in modern military aircraft poses a significant challenge to existing non-destructive inspection (NDI) technologies. In older aluminum aircraft, NDI could be performed by an inspector either visually or audibly, using a coin tap. Composite aircraft are more complex, since severe defects (e.g. ballistic impact damage, fluid ingress, delamination, adhesive disbonds) may not be visually detectable at the surface.
Thermal Wave Imaging, Inc. (TWI) developed a novel system for thermographic NDI of composite aircraft capable of inspecting a large area (~ 100 ft^2) in a short time (10 minutes). Unlike most conventional NDI methods, the Large Standoff Large Area Thermography (LASLAT) system operates at a standoff distance of 10-15 feet from the aircraft and builds an aggregate image of the inspection area by serially interrogating an Instantaneous Field of View (IFOV) of ~20” x 15”.
TWI (winner of the CTMA Technology Challenge in 2017) is partnering with NCMS and Warner-Robins AFB on a CTMA project to test the LASLAT system on RQ-4 Global Hawk unmanned surveillance platform. The Global Hawk can cover over 40K square miles per day and has a maximum speed of nearly 400 MPH while flying for 32+ hours per mission.
The LASLAT Inspection was completed on AUG 27-28 at Warner-Robins AFB. “The inspection went exactly as planned. They seemed pleasantly surprised that we could see the sub-surface structure of the aircraft and even an area where a patch had been applied,” Maria Beemer, technology lead on the LASLAT project at TWI.
The LASLAT NDI system is being tested to verify the repair of Global Hawk composite airframe structures. NCMS is working to evaluate the advantages of LASLAT over current NDI methodologies. The ability to repair and inspect composite structure will be a key requirement as the USAF transitions to next-generation aircraft. Results of this project will likely be of great interest to all Services that use composite material on aircraft, vehicles, or other equipment.