In-Situ Detection of Hidden General and Pitting Corrosion of Aircraft Structure

Innovative Materials Testing Technologies, Inc., (IMTT), supported by Lockheed Martin Company, propose a methodology, based on a combination of two novel technologies, for the in-situ measurement of general and pitting corrosion in aluminum structures to meet the requirements stated in the solicited topic ¡°In-Situ Detection of Hidden General and Pitting Corrosion of Aircraft Structure¡±. The two technologies are: 1. Flat-Geometry Remote Field Eddy Current (FG_RFEC) technique for deeply hidden and inaccessible corrosion detection and quantification, and 2. Magnetic Carpet Probe (MCP) technique for large area, static and instant detection and quantification of corrosion under aircraft paint/coating. FG_RFEC technique is a unique technique in the world that can penetrate deeply through multiple metallic and composite layer aircraft structures and detect hidden corrosion and cracks buried within. Typical examples include: 1. Detect 0.040¡± deep corrosion through 0.600¡± ¨C 0.700¡± thick multiple layer aluminum structure; 2. Detect 0.006¡± deep corrosion through 0.367¡± thick multiple layer aluminum structure; 3. Detect 0.092¡±diameter and 0.004¡± deep corrosion pit on the backside of a 1/8¡± thick aluminum plate. The detected corrosion signals from general corrosion or corrosion pitting can be quantified using software installed in  IMTT¡¯s Super Sensitive Eddy Current (SSEC) instrument. MCP technique was developed under an FAA project for large area, static and instant detection and quantification of crack on titanium components. An MCP is coil array built in a 0.004¡± to 0.008¡± thick flexible printed circuit board. It can be conformed to a curved surface to inspect for corrosion and/or cracks. An MCP covers a relatively large area under inspection. All actions, including the C-scan, imaging and corrosion identification, are done in few seconds electronically. No mechanical movement is needed. IMTT has proved experimentally that this technique can also be used for large area, static and instant detection/quantification of corrosion under up to 0.060¡± thick coating. The two technologies are complementary each other. MCP is excellent in detection of corrosion under paint/coating. FG_RFEC technology is excellent in detection of corrosion hidden in inaccessible areas. An appropriate combination of the two technologies can provide a complete package for corrosion inspection without having the aircraft disassembled. BENEFIT: The proposed technology combination will enable the ability to detect the corrosion activity in hidden and inaccessible areas in a field environment without aircraft disassembly.  This will reduce maintenance hours, reduce cost, and improve aircraft availability. Success in meeting the requirement of this SBIR topic will provide military aircraft with a corrosion prognostics capability. Corrosion detection is a common issue for both military and commercial airplanes. Significant Return of Investment (ROI) is expected from commercialization of these two techniques. Therefore, commercial aircraft manufacturers, owners, and operators will capitalize on the benefits and ROI associated with these technologies.)