PEER REVIEW
20
th
Australian International Aerospace Congress, 27-28 November 2023, Melbourne
20th Australian International Aerospace Congress
ISBN number: 978-1-925627-66-4
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Diagnostics and tracking of helicopter’s engine shaft
bearing inner ring degradation using cyclostationary
methods
Alexandre Mauricio
1,2
, Arnaud Talon
3
, Vercoutter Agathe
3
, Karl Janssens
4
and Konstantinos Gryllias
1,2
1
Department of Mechanical Engineering, Faculty of Engineering Science, KU Leuven, 3001, Leuven, Belgium
2
Dynamics of Mechanical and Mechatronic Systems, Flanders Make, Leuven, Belgium,
3
SAFRAN Helicopter EnginesAvenue Joseph Szydlowski 64511 Bordes - France
4
Siemens Industry Software NV, Interleuvenlaan 68, B-3001, Leuven, Belgium
Abstract
The components of an engine’s helicopter gearbox are vulnerable to fatigue and therefore
Health and Usage Monitoring Systems are intended to be developed, focusing towards early,
accurate and on time detection of degradation’s initialisation with limited false alarms and
missed detections. The main aim of HUMs is to enhance the helicopters’ engine operational
reliability and functionality and to improve flight airworthiness.
Bearings are one of the components of essential interest of helicopter’s engine drivetrains, as
they support the rotating components or gears, and early degradation detection is necessary to
prevent sudden breakdown. On the other hand, bearing signals are often masked by noise and
other vibration sources, which further challenges their early detection. Over the recent decade,
several cyclostationary tools have been proposed in order to extract the bearing health state
information from vibration data. These methods are based on the demodulation of the signals
using either the Hilbert Transform or the Spectral Correlation and/or Coherence, in tandem with
band pass filtering using band selection tools.
In this paper, the performance of several cyclostationary-based indicators targeting to early
bearing degradation detection is evaluated on a special dataset, including vibration and particle
data, captured on a dedicated test bed of a helicopter engine drivetrain during a lifetime test. A
bearing with an inner race indented in three positions was mounted on the test bed and was run
until its end of life, when the full surface of the inner race was spalled.
Keywords: Condition monitoring, vibration analysis, bearing diagnostics, cyclostationarity,
helicopter drivetrain
Introduction
In order to ensure safety and improve engine efficiency during operation, Research and
Development programs are conducted on engine bearings especially due to their high speed and
heavy load operating conditions which may cause fatigue and degradation of their rotating
components. However, helicopter engines are complex rotating machinery and the vibration
signatures generated due to degradation of internal components, such as bearings, are
