Mitsubishi Heavy Industries Technical Review Vol. 52 No. 1 (March 2015) 42 *1 Chief Staff Manager, Nagoya Research & Development Center, Technology & Innovation Headquarters *2 Nagoya Research & Development Center, Technology & Innovation Headquarters *3 University of Tokyo *4 Yokogawa Electric Corporation *5 The Materials Process Technology Center (Sokeizai Center) Cost Reduction Technology for Airframe Maintenance TAKASHI YARI *1 NOZOMI SAITO *2 KAZUO HOTATE *3 SATOSHI MATSUURA *4 ENOMOTO KIYOSHI *5 Recently, aircraft structures adopt a damage tolerance design and its airworthiness is maintained through the periodical inspections specified in the maintenance plan before it becomes fatal. The establishment of health monitoring technology to continuously monitor the condition and airworthiness of an aircraft structure will hopefully lengthen the present inspection intervals and reduce maintenance costs, thereby improving the efficiency of aircraft operation. The authors developed an optical fiber sensor-based system for wide-area diagnosis of aircraft structures and evaluated its applicability to adopt structure condition monitoring through flight demonstration testing. It was found that the developed system can monitor the structural condition during flight operation. | 1. Introduction In aircraft operation, shorter aircraft inspection intervals and lower monitoring costs are among the matters required for higher managerial efficiency. Accordingly, there is hope for the commercialization of a structural health monitoring (hereinafter abbreviated as SHM) system that can be substituted for the structural inspection of aircraft during operations. A variety of approaches have been adopted to implement such a system and many researchers and engineers are striving for its commercialization. Among such efforts, the authors are engaged in R&D for the commercialization of the SHM system through the application of Brillouin optical correlation domain analysis (hereinafter abbreviated to BOCDA) technology to make wide-area diagnosis available with an optical fiber sensor that is light-weight, causes no electromagnetic interference, and is capable of being embedded into composite material. BOCDA can characteristically measure distributed strain along the entire length of an optical fiber and dynamic strain at arbitrary points. Figure 1 shows a conceptual image of its application to the SHM system based on such characteristics. The evaluation of optical fiber sensors placed across the airframe structure is now designed to identify the fatigue damage/structural life through the monitoring of damage occurrence due to changes of distributed strain or the measurement of dynamic strain. Figure 1 SHM System Application Concept