Optical interrogators are traditionally very delicate systems. The Fibre Optic Processing Unit (FOPU) has been subjected to High temperature, Low temperature, Vibration, Shock and Humidity. The FOPU showed satisfactory results in all of these tests, and in many others and is considered suitable for aerospace use.
The entire optical load measurement system (a pair of axle sensors, an optical harness and a FOPU) was fitted to a landing gear axle and installed into the test rig. A comprehensive test campaign has been performed. The axle sensors were instrumented with strain gauges and temperature sensors for comparison. It started with calibration tests and moved on to high-load tests, dynamic tests, tests at high and low temperatures, shock and vibration tests. The outputs of the ALGeSMo systems were continuously recorded and compared to the loads actually applied and the measurements of the strain gauges and temperature sensors. Three successive iterations of axle sensors have been tested, each of them improving on the issues identified on the previous one. The loads applied during testing are representative of aircraft operation. Loads along all three axis of the landing gear and the torque about the wheel axles were measured and showed a very good correlation with the applied loads. The load measurements were generally within the required accuracy, with the exception of a few data points.
The research activities have advanced the state of the art in several key areas for the deployment of optical sensing systems for safety-critical applications (e.g. integration of optical fibres into composite material, robust optical connections, avionic-compliant optical interrogator and landing gear load measurement). The technology building blocks developed during this project can also be used in other aerospace applications, not only for landing gear load measurement. There is a general consensus in the aerospace industry that optical sensing can bring significant benefits. Thanks to ALGeSMo, the project partners and more generally the European industry are better prepared for the “more optical aircraft”
Dissemination included the general public, European industries and organisations offering engineering training. The dissemination activities of the project were of course impacted by the COVID-19 crisis. The original plan was to increase dissemination activities in conferences,expos and fairs towards the end of the project once the final system test results were available. These events could not take place but dissemination and communication activities are still planned after the end of the project.
Exploitation is based on the anticipation that the technology will be adopted in the next evolution of the Airbus A320 family of aircraft and into the ZEROe concepts. The ALGeSMo advanced load sensing capability forms part of an integrated solution across landing gear systems. This integrated solution is an enabler for a step change in availability and operability for Landing Gear which ultimately aims to reduce the operational costs and increase the value of the aircraft.
