As fleets of aircraft age, corrosion of metal parts becomes a very real economic and safety concern. Corrosive agents like moisture, salt, and industrial fluids—and even internal problems, like leaks and condensation—wear away and, especially over time and repeated exposure, begin to corrode aircraft.
Costs of repairs, which often involve replacing entire panels, downtime for fleet craft, and the potential loss of use of a vehicle all contribute to the economic concerns. In the United States alone, this is a multibillion dollar problem. In terms of safety, corrosion can be so widespread as to cause problems with the structural integrity of the craft, but it can also be just as dangerous when localized, like eating away at electrical wires or rusting away at crucial landing gear components.
NASA is invested in the development of new materials and material coatings to retard and prevent corrosion, but it is also researching methods for monitoring corrosion on existing aircraft.
Moisture can lead to corrosion in an aircraft, and altered pH can indicate that corrosion is occurring. Intelligent Optical Systems Inc. (IOS), of Torrance, California, completed Phase I and II Small Business Innovation Research (SBIR) contracts with NASA’s Langley Research Center to develop moisture- and pH-sensitive sensors to detect corrosion or pre-corrosive conditions. As opposed to typical inspection equipment, like ultrasound or X-ray imaging, this technique can warn of potentially dangerous conditions before significant structural damage occurs. This new type of sensor uses a specially manufactured optical fiber whose entire length is chemically sensitive, changing color in response to contact with its target. These sensor fibers, embedded directly in aluminum “lap joints,” have detected the location—to within 2 centimeters—and alkalinity of potentially corrosive moisture incursions.
After completing the work with NASA, the company received funding through a Defense Advanced Research Projects Agency (DARPA) Phase III SBIR to develop the sensors further for detecting chemical warfare agents. The sensors proved just as successful at locating and identifying specific chemicals as they had been at detecting moisture and pH levels. The next stage of development involved working with the U.S. Department of Defense (DoD) to fine-tune the sensors for detecting potential threats, such as toxic industrial compounds and nerve agents. Through the DoD contract, the company has set up beta testing in major metropolitan areas.