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Public reporting burden for tiiis collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Sereices, Directorate for Information Operations and Reports 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Papenwork Reduction Project (0704-0188) Washington DC 20503 AGENCY USE ONLY (Leave blank) TITLE AND SUBTITLE REPORT DATE August 2004 REPORT TYPE AND DATES COVERED Technical MemorandumA Foreign Object Damage Event Detector Data Fusion System for Turbofan Engines AUTHOR(S)James A. Turso and Jonathan S. Litt PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)National Aeronautics and Space Administration John H. Glenn Research Center at Lewis Field Cleveland, Ohio 44135-3191 A Data Fusion System designed to provide a reliable assessment of the occurrence of Foreign Object Damage (FOD) in a turbofan engine is presented. The FOD-event feature level fusion scheme combines knowledge of shifts in engine gas path performance obtained using a Kalman filter, with bearing accelerometer signal features extracted via wavelet analysis, to positively identify a FOD event. A fuzzy inference system provides basic probability assignments (bpa) based on features extracted from the gas path analysis and bearing accelerometers to a fusion algorithm based on the Dempster-Shafer-Yager Theory of Evidence. Details are provided on the wavelet transforms used to extract the foreign object strike features from the noisy data and on the Kalman filter-based gas path analysis. The system is demonstrated using a turbofan engine combined-effects model (CEM), providing both gas path and rotor dynamic structural response, and is suitable for rapid-prototyping of control and diagnostic systems. The fusion of the disparate data can provide significantly more reliable detection of a FOD event than the use of either method alone. The use of fuzzy inference techniques combined with Dempster-Shafer-Yager Theory of Evidence provides a theoretical justification for drawing conclusions based on imprecise or incomplete data. • TECHNICAL PUBLICATION. Reports of conipleted research or a major significant phase of research that present the results of NASA programs and include extensive data or theoretical analysis. Includes compilations of significant scientific and technical data and information deemed to be of continuing reference value. NASA's counterpart of peerreviewed formal professional papers but has less stringent limitations on manuscript length and extent of graphic presentations. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)National SUBJECT TERMS• TECHNICAL MEMORANDUM. Scientific and technical findings that are preliminary...

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