Title: A wavelet-based index for fault detection and its application in condition monitoring of helicopter drive-train components

Authors: Kareem M. Gouda; Joshua A. Tarbutton; Mohammed A. Hassan; David Coats; Abdel-Moez E. Bayoumi

Addresses: Department of Mechanical Engineering, Condition-Based Maintenance Research Center, University of South Carolina, Columbia, SC 29208, USA ' Department of Mechanical Engineering, Condition-Based Maintenance Research Center, University of South Carolina, Columbia, SC 29208, USA ' Electrical Engineering Department, Fayoum University, Fayoum 63514, Egypt ' Department of Electrical Engineering, Condition-Based Maintenance Research Center, University of South Carolina, Columbia, SC 29208, USA ' Condition-Based Maintenance Research Center, University of South Carolina, Columbia, SC 29208, USA

Abstract: This paper presents a new condition indicator using wavelet analysis for the purpose of fault detection in an AH-64 gearbox. Historically, vibration-based condition indicators from employed component monitoring equipment are derived from both temporal and spectral domain analysis. However, these indicators failed to accurately capture high order correlations for the gearbox study addressed in this paper. An improved approach is necessary to overcome limitations of traditional vibrational monitoring techniques. The proposed condition indicator is derived from the Morlet continuous wavelet .transform The power spectra obtained from the wavelet transform coefficients at a certain scale or frequency are added together and then are normalised to one composite signal, denoted by a numeric index. Concepts of the wavelet index are discussed. This index is applied using real-world vibration data from a tail rotor gearbox with an output seal leak as part of condition-based maintenance practices. Results demonstrate potential of the proposed wavelet index to more effectively capture the fault when compared to gearbox condition indicators. [Received 24 January 2014; Revised 28 August 2014; Accepted 3 October 2014]

Keywords: condition indicators; helicopter gearbox; condition-based maintenance; CBM; fault detection; condition monitoring; wavelet transform; helicopter drivetrains; drivetrain components; vibration analysis; tail rotor gearboxes; seal leak.

DOI: 10.1504/IJMR.2015.067619

International Journal of Manufacturing Research, 2015 Vol.10 No.1, pp.87 - 106

Published online: 22 Apr 2015 *

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