A Versatile and Computationally Efficient Condition Indicator for AH-64 Rotorcraft Gearboxes
type: CreativeWork
description: The CBM research at University of South Carolina is targeted at achieving some of the CBM objectives for rotorcrafts in collaboration with South Carolina Army National Guard. The current research study is motivated by the endeavor to enhance condition monitoring objectives by evaluating the condition indicators (CI) that have been implemented currently on the aircraft in operation. For the purpose of this research three tail rotor gearbox have been tested to simulate severe lubricant starved conditions. The three test articles have failed in three different modes. The TGB article-1 had severe damage of the input gear teeth. For the second TGB article the testing was terminated when an input gear tooth broke. The third TGB article did not suffer significant damage to its gear teeth, but the testing was aborted due to an increase in temperature. For all the three articles, a significant increase in gear mesh second harmonics was observed but the condition indicators have not been successful in providing a warning well in advance. The only condition indicator that has triggered caution alarm was TGB lateral bearing energy CI. From the evaluation of condition indicators it is found that only the DA1 CI has shown a very sharp increase in its value. The FM0 and FM4 CI have also shown noticeable fluctuations but the variation was not severe to create any alarm. This suggests that if the existing CIs do not perform up to the expectations then an alternate CI that is either better in anticipating failure or produce similar results with relatively lower computational expense is beneficial. In the current research, a new condition indicator that is relatively simpler compared to the FM4, ER, SLF, SI condition indicators and has the ability to offset some of the limitations of Discrete Fourier transform (DFT) is proposed. The proposed CI is defined as Asynchronous to Synchronous Energy ratio in Time domain (ASET). As the name suggests, the ASET for a component rotating at a par…
abstract: The CBM research at University of South Carolina is targeted at achieving some of the CBM objectives for rotorcrafts in collaboration with South Carolina Army National Guard. The current research study is motivated by the endeavor to enhance condition monitoring objectives by evaluating the condition indicators (CI) that have been implemented currently on the aircraft in operation. For the purpose of this research three tail rotor gearbox have been tested to simulate severe lubricant starved conditions. The three test articles have failed in three different modes. The TGB article-1 had severe damage of the input gear teeth. For the second TGB article the testing was terminated when an input gear tooth broke. The third TGB article did not suffer significant damage to its gear teeth, but the testing was aborted due to an increase in temperature. For all the three articles, a significant increase in gear mesh second harmonics was observed but the condition indicators have not been successful in providing a warning well in advance. The only condition indicator that has triggered caution alarm was TGB lateral bearing energy CI. From the evaluation of condition indicators it is found that only the DA1 CI has shown a very sharp increase in its value. The FM0 and FM4 CI have also shown noticeable fluctuations but the variation was not severe to create any alarm. This suggests that if the existing CIs do not perform up to the expectations then an alternate CI that is either better in anticipating failure or produce similar results with relatively lower computational expense is beneficial. In the current research, a new condition indicator that is relatively simpler compared to the FM4, ER, SLF, SI condition indicators and has the ability to offset some of the limitations of Discrete Fourier transform (DFT) is proposed. The proposed CI is defined as Asynchronous to Synchronous Energy ratio in Time domain (ASET). As the name suggests, the ASET for a component rotating at a par…
author: Nooli, Praveen Kumar
keywords: Engineering, Mechanical Engineering, condition based maintenance, condition indicators, gearbox, Rotorcrafts, Vibration, vibration diagnostics
date published: 2011-01-01T08:00:00Z
date modified: 2026-07-24T04:37:28Z
provider: University of South Carolina
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of South Carolina