Resonant Eddy Current Sensor (RECS) for C-Paint Measurement on Advanced Aircraft

Advanced aircraft use carbon fiber composite as structural skin to replace heavier metals. The higher resistivity carbon requires a conductive paint (C-paint) to prevent electromagnetic interference with avionics in the aircraft. Due to the high cost of the paint, the Air Force has tight specifications on the amount of paint to be applied to meet cost and performance requirements. The current technology (traditional eddy current sensors) used to verify this conductive paint thickness have been found to have poor reliability, increasing costs as more paint must be applied to ensure minimum thickness limits are reached. Furthermore, the current scanning process is labor-intensive leading to lower throughput from the depots. CTG proposes that the Resonant Eddy Current Sensor (RECS) can be adapted as a solution to this problem. This sensor design is based upon traditional eddy current principals but makes use of resonances within the coil to greatly amplify the sensitivity of the device. This device is designed to very lightweight (~1-2 pounds) and compact, greatly aiding in the portability of the unit. Under the proposed effort, CTG will design and construct probes capable of detecting the paint thickness within acceptable accuracy limits. In addition, these probes will be mounted onto robotic platforms to allow for full automated scanning. By the end of the proposed effort, it is expected that CTG will have generated a probe and software capable of detecting paint thickness at a level of accuracy and reliability superior to the current technology. This solution will also be demonstrated on a robot system, allowing for large increases in speed and reductions in labor cost per aircraft. Overall, this technology will improve Air Force capabilities by reducing costs and increasing throughput for aircraft coatings.