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Advanced Landing Gear Sensing and Monitoring

Periodic Reporting for period 3 - ALGeSMo (Advanced Landing Gear Sensing and Monitoring)

Reporting period: 2018-09-01 to 2019-08-31

Advanced Landing Gear Sensing & Monitoring – ALGeSMo – is a system that will measure load at the landing gear to provide loads data for use on the aircraft systems for integration with aircraft health monitoring, hard landing detection, flight management and flight controls. The project consists of developing and flight testing landing gear loads measurement technology towards further functional integration in large aircraft avionics systems. The ALGeSMo project is concerned with the integration of sensors into large passenger aircraft landing gear to provide robust, accurate, reliable load measurement and the potential for health monitoring capability. The sensors measure loads using a new strain gauge technology which is based on optical Fibre Bragg Grating sensors. This technology is essential as it enables measurement of the very high strains experienced during a heavy landing and is robust to the harsh environment. The system therefore relies on cutting edge opto-electrical hardware to drive the sensors. The system will also measure the compression of each landing gear shock absorber by measuring the relative angle between the landing gear main fitting and the torque link.

The objective of this project is to satisfy the topic requirements as set out by Airbus (Topic Manager) and specifically the development and delivery of the following:
• A Fibre Bragg Grating (FBG) optical sensor system to accurately detect and translate landing gear strain and torque to the aircraft control systems.
• A state-of-the-art and highly accurate integrated photonics fibre-optic interrogator. This will make integration and certification of the system highly achievable compared to existing optical interrogator systems.
• Detailed design of system architecture and integration to ensure that the Design Assurance Level (DAL) requirement can be achieved with a production solution beyond this project.
• Definition and build of loading and calibration rigs in order to characterise sub-system and system components using a full landing gear axle assembly.
Within the 36 months of the project the work performed led to the following major achievements:
• Specification for the complete end-to-end optical system and associate components to achieve the necessary functional, performance, and safety requirements.
• Completion of the system architecture design.
• Design and development testing of a first FBG axle sensor that will be further refined in the next period.
• Completion of the design of a ruggedized and integrated Fibre Optic Interrogator and Optical Processing Unit.
• Design of a ruggedized optical harness and connector system.
• Specification and definition of a sensor to measure the landing gear shock absorber compression
• Completion of the design and manufacture of a full-scale test rig to undertake calibration and loading of the end-to-end system
• Detail design of FBG axle sensor released for manufacture
Airbus aircraft do not currently incorporate landing gear load sensors into their production aircraft; it is currently the responsibility of the pilot to declare any landing overload situation.

The introduction of a landing gear load measurement system would provide the following benefits:
• Accurate and rapid classification of hard landing and overload events
• Automated and accurate weight on wheels and center of gravity position measurement
• Automated take-off settings for HTP trim and Thrust (tail-strike protection)
• Optimised ground trajectory and load control (coordinated turns using steering and braking)
• Sensitive detection of air-ground transition
• Landing gear life and structural health assessment
• Landing gear health monitoring in support of total care maintenance packages

The primary objective of the Advanced Landing Gear Sensing and Monitoring (ALGeSMo) project is to deliver a state-of-the-art optically-based load monitoring system for aircraft landing gear. This will yield a step change in the way landing gear is utilised and managed in operational and flight situations, leading to a new paradigm in aircraft availability and operability. This will assist the development of European capability within this domain such that Europe will be well-positioned to provide state-of-the-art equipment to future aircraft development.
ALGeSMo Fibre Optics Processing Unit Prototype
ALGeSMo Test Rig
ALGeSMo Fibre Optics Processing Unit (FOPU) . 3D CAD view
ALGeSMo high level system schematics