[2F6] Experimental validation of bearing fault progression in a turboshaft engine using vibration and oil debris monitoring
T Bublil, J Nickell, E Bechhoefe and J Bortman
Bearing failures in gas turbine engines are a major concern in aerospace and industrial applications, often leading to costly maintenance and unexpected downtime. Condition monitoring techniques, such as vibration analysis and oil debris monitoring (ODM), are essential for early fault detection and predictive maintenance. This study aims to enhance these techniques by experimentally validating fault progression in a controlled set-up.
As part of a collaboration between the AFRL and the PHM Laboratory, a first-of-its-kind experiment was conducted to investigate the impact of a faulty bearing on a turboshaft engine. A spall-type defect, previously initiated on the inner race of the bearing, was studied under real operating conditions. The experiment was performed using a T63-A-700 turboshaft engine operating under controlled conditions. The faulty bearing, with an induced spall-type defect on the inner race, was installed in the engine, which was then run at a constant speed of 800 r/s for five hours. During this time, vibration sensors were mounted at key locations to capture acceleration signals, while an ODM system continuously tracked wear particle generation. The tested bearing was located on an inner shaft, with no direct contact with the outer structure of the engine where the accelerometer was positioned. A baseline test using a healthy bearing was also conducted for comparison.
Throughout the test, the defect progressed, leading to a gradual degradation of the condition of the bearing. The primary objective was to validate diagnostic and prognostic methodologies developed in the laboratory alongside well-established fault detection techniques. Key methods employed included identifying characteristic bearing fault frequencies in the spectrum, envelope analysis and time-synchronous averaging (TSA) to isolate synchronous components from the signal. The findings contribute to a deeper understanding of bearing failure progression and its detection in gas turbine engines, enhancing predictive maintenance strategies.
As part of a collaboration between the AFRL and the PHM Laboratory, a first-of-its-kind experiment was conducted to investigate the impact of a faulty bearing on a turboshaft engine. A spall-type defect, previously initiated on the inner race of the bearing, was studied under real operating conditions. The experiment was performed using a T63-A-700 turboshaft engine operating under controlled conditions. The faulty bearing, with an induced spall-type defect on the inner race, was installed in the engine, which was then run at a constant speed of 800 r/s for five hours. During this time, vibration sensors were mounted at key locations to capture acceleration signals, while an ODM system continuously tracked wear particle generation. The tested bearing was located on an inner shaft, with no direct contact with the outer structure of the engine where the accelerometer was positioned. A baseline test using a healthy bearing was also conducted for comparison.
Throughout the test, the defect progressed, leading to a gradual degradation of the condition of the bearing. The primary objective was to validate diagnostic and prognostic methodologies developed in the laboratory alongside well-established fault detection techniques. Key methods employed included identifying characteristic bearing fault frequencies in the spectrum, envelope analysis and time-synchronous averaging (TSA) to isolate synchronous components from the signal. The findings contribute to a deeper understanding of bearing failure progression and its detection in gas turbine engines, enhancing predictive maintenance strategies.
