AE 417 · Aerospace Structures and Instrumentation Laboratory · Fall 2025 · ERAU
A Ridgid Micro CA-150 borescope camera was connected to a Funai LED display and inserted into the interior of a metallic aircraft wing airfoil section. The camera was navigated along the inner surface, with brightness adjusted to minimize glare on the metallic skin. Photographs were taken at locations of interest and reviewed for surface-level damage indicators.
Results: Visible scratches and cracks were identified near the rivet holes on the interior surface. These are consistent with stress-concentration-driven fatigue damage from cyclic loading. No corrosion or delamination was observed. Borescope imaging proved effective for preliminary screening of difficult-to-access interior surfaces, though it cannot detect subsurface damage.
Thermography: The FLIR T440 thermal camera imaged a sheet of paper before and after applying cold water droplets and a hand imprint. The camera clearly resolved the temperature differential — cold water appeared as dark (lower temperature) zones and the hand imprint as warm (higher temperature) regions. This demonstrated thermography's sensitivity to surface thermal nonuniformities, applicable to detecting disbonds, coolant leaks, or heat-affected zones in aerospace structures.
Radiography: An X-ray system (film/digital) imaged a welded aluminum plate and an Apple Watch. The weld X-ray revealed interior bead geometry useful for quality assurance; the watch X-ray resolved internal electronic components. Complex assemblies showed overlapping features that complicate defect discrimination — a known limitation of projection radiography.
Liquid Penetrant: A fluorescent penetrant was sprayed onto an aluminum pressure vessel, allowed to dwell for ≈10 minutes, wiped clean, and developed. Under UV illumination, at least eight discrete damage indications appeared as bright zones contrasting the green developer background. These included scratches and cracks invisible under normal light, confirming the dye/developer system's sensitivity to shallow, tight surface discontinuities.
A portable Quantum TE ultrasonic inspection device with a 5 MHz piezoelectric transducer was coupled to stepped aluminum calibration blocks (SCB) using ultrasonic couplant gel. The transducer was swept across the block surface and the echo time-of-flight patterns recorded at each thickness step.
Results: As the transducer moved from the tallest (≈24.96 mm) to the shortest (≈3.32 mm) section, the spacing between successive back-wall echoes decreased proportionally, confirming the ultrasonic pulse-echo thickness measurement principle. Echo amplitude decreased slightly with step edges due to wave scattering at the ledges. The technique is directly applicable to detecting cracks, corrosion thinning, and delaminations in aircraft skins and turbine blades without requiring access to the back surface.