PSI - Issue 5

Chad Forrest/ Structural Integrity Procedia 00 (2017) 000 – 000

2

1154 The technological readiness of the landing gear SHM sensors has advanced, with several SHM sensors currently flying on aircraft for loads spectrum data collection purposes. This paper varies from prior publications for the European Workshop on Structural Health Monitoring, in that the prior applications concentrated on fluid level detection for CBM purposes — while this paper enhances the SHM system capability via the addition of direct load monitoring devices throughout the landing gear structural load path. Early development of the landing gear SHM system was presented at the 6 th European Workshop on Structural Health Monitoring, in a paper regarding Aircraft Landing Gear Fluid Level and Landing Energy Monitoring System . The focus of that paper was the detection of improper fluid level and hard landings via the SHM system and sensors. This paper advances the prior publications via the addition of new direct load sensors into the SHM system, providing capabilities for fatigue damage tracking of landing gear components. The landing gear SHM system also allows data fusion of direct loads monitoring data into fatigue life assess ents. This feature is provided via utilization of communication to platform HUMS and associated flight records for data assurance purposes. The interface and communication of the SHM control units to the aircraft HUMS equipment provides the ability to synchronize loads data, allowing for elimination/reduction of estimates on landing gear loads usage and service life. he SHM technology and algorithms also provide the ability for a paradigm shift in aircraft maintenance, utilizing strut servicing detection algorithms. Previously, automatic detection of an improperly serviced strut while the aircraft is on the ground was not possible. The incorporation of the SHM sensors and unique aircraft algorithms changes the maintenance approach, allowing for appropriate CBM based on the actual condition of the landing gear component service condition. High-fidelity laboratory testing of the SHM components using form, fit and functional hardware on a landing gear assembly has been completed. The completed demonstration testing included landing gear multi-body dynamic odels, and validation of that model with the laboratory testing. The high-fidelity laboratory testing of loading events was accomplished on a full main landing gear assembly. The gear was instrumented as close as possible to the on aircraft configuration. The landing gear as secured in the test rig, in a similar manner to the landing gear attachment to the aircraft. The responses to loading events, as recorded by the SHM system, provided known loads, measured pressures and stresses to verify the landing gear hydrodynamic model. Landing gear model simulations were performed to create a virtual landing gear strut to predict the dynamic behavior of the strut servicing conditions, over a wide range of operational variables. Formal verification and validation of the landing gear model was accomplished, using a variety of available aircraft data — inclu ing instrumented flight test ata. The SHM technology also provides a safety benefit with the improvement of weight and balance calculations. The landing gear sensors and associated control/interface units provide the ability to calculate actual weight and balance information. This information can then interface with other platform HUMS systems for use in improving maintenance practices, or enhancing crew safety during operations. Chad Forrest et al. / Procedia Structural Integrity 5 (2017) 1153–1159 Chad Forrest/ Structural Integrity Procedia 00 (2017) 000 – 000 2 The technological readiness of the landing gear SHM sensors has advanced, with several SHM sensors currently flying on aircraft for loads spectrum data collection purposes. This paper varies from prior publications for the European Workshop on Structural Health Monitoring, in that the prior applications concentrated on fluid level detection for CBM purposes — while this paper enhances the SHM system capability via the addition of direct load monitoring devices throughout the landing gear structural load path. Early development of the landing gear SHM system was presented at the 6 th European Workshop on Structural Health Monitoring, in a paper regarding Aircraft Landing Gear Fluid Level and Landing Energy Monitoring System . The focus of that paper was the detection of improper fluid level and hard landings via the SHM system and sensors. This paper advances the prior publications via the addition of new direct load sensors into the SHM system, providing capabilities for fatigue damage tracking of landing gear components. The landing gear SHM system also allows data fusion of direct loads monitoring data into fatigue life assessments. This feature is provided via utilization of communication to platform HUMS and associated flight records for data assurance purposes. The interface and communication of the SHM control units to the aircraft HUMS equipment provides the ability to synchronize loads data, allowing for elimination/reduction of estimates on landing gear loads usage and service life. The SHM technology and algorithms also provide the ability for a paradigm shift in aircraft maintenance, utilizing strut servicing detection algorithms. Previously, automatic detection of an improperly serviced strut while the aircraft is on the ground was not possible. The incorporation of the SHM sensors and unique aircraft algorithms changes the maintenance approach, allowing for appropriate CBM based on the actual condition of the landing gear component service condition. High-fidelity laboratory testing of the SHM components using form, fit and functional hardware on a landing gear assembly has been completed. The completed demonstration testing included landing gear multi-body dynamic models, and validation of that model with the laboratory testing. The high-fidelity laboratory testing of loading events was accomplished on a full main landing gear assembly. The gear was instrumented as close as possible to the on aircraft configuration. The landing gear was secured in the test rig, in a similar manner to the landing gear attachment to the aircraft. The responses to loading events, as recorded by the SHM system, provided known loads, measured pressures and stresses to verify the landing gear hydrodynamic model. Landing gear model simulations were performed to create a virtual landing gear strut to predict the dynamic behavior of the strut servicing conditions, over a wide range of operational variables. Formal verification and validation of the landing gear model was accomplished, using a variety of available aircraft data — including instrumented flight test data. The SHM technology also provides a safety benefit with the improvement of weight and balance calculations. The landing gear sensors and associated control/interface units provide the ability to calculate actual weight and balance information. This information can then interface with other platform HUMS systems for use in improving maintenance practices, or enhancing crew safety during operations. © 2017 The Authors. Published by Elsevier B.V. Peer-r view under responsibility of the S i ntific Committee of ICSI 2017. 1. Introduction NAVAIR contracted with ES3 to continue development of a landing gear Structural Health Monitoring SHM system through the Small Business Innovative Research (SBIR) program, via a Phase II award on the N121-043 topic. Although the primary focus of the development program is for fixed wing aircraft, the proposed solution is directly transferable to other Navy and commercial fixed wing and rotorcraft. The system presented address aircraft Health and Usage Monitoring System (HUMS) and Condition Based Maintenance (CBM) in the following topic areas: (1) advanced landing gear sensors for direct load measurement; (2) data fusion of direct loads monitoring data into fatigue life assessments; (3) paradigm shifts in aircraft maintenance utilizing fluid-level detection algorithms; (4) system verification and validation; and (5) safety and maintenance benefits. NAVAIR contracted with ES3 to continue development of a landing gear Structural Health Monitoring SHM system through the Small Business Innovative Research (SBIR) program, via a Phase II award on the N121-043 topic. Although the primary focus of the development program is for fixed wing aircraft, the proposed solution is directly transferable to other Navy and commercial fixed wing and rotorcraft. The system presented address aircraft Health and Usage Monitoring System (HUMS) and Condition Based Maintenance (CBM) in the following topic areas: (1) advanced landing gear sensors for direct load measurement; (2) data fusion of direct loads monitoring data into fatigue life assessments; (3) paradigm shifts in aircraft maintenance utilizing fluid-level detection algorithms; (4) system verification and validation; and (5) safety and maintenance benefits. Keywords: Landing Gear; Structural Health Monitoring 1. Introduction © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. Keywords: Landing Gear; Structural Health Monitoring