To be more precise, TECNALIA is designing the structure that will house the different sensors developed, based on the above-mentioned techniques and which will allow correct interaction of the same with the fluids to be analysed. The design will comply with aeronautical standards and will be tested in such a way that the qualification and homologation time of the product resulting from the project will be minimised. The "Super Sky Sense" project consortium consists of Airbus France, EADS Deutschland, Lufthansa Technik Budapest, Loughborough University, Instytut Lotnictwa, Compañía Española de Sistemas Aeronáuticos S.A. Sofrance, Universidad Complutense de Madrid, GIE EADS CCR, Centre de Transfert de Technologies Ceramiques y Group D’etudes en Procedes de Separation, as well as TECNALIA and INTERLAB. Aeronautical hydraulic fluids are hygroscopic, meaning that they can absorb or react with water, making their duration very unpredictable. The performance of aircraft hydraulic systems is affected by the condition of the hydraulic fluid and, if its degradation is not detected, this could lead to the aircraft control systems being damaged. At present, identifying the condition of aircraft hydraulic fluid is difficult, costly and time-consuming. This means that the fluid is normally checked less than once a year, with the risk of carrying out unprogrammed maintenance if the fluid exceeds its “sell-by date”. Interrupting airline schedules involves very high costs. This project proposes the development of and optimum maintenance concept based on an autonomous onboard system able to monitor the conditions of hydraulic fluid and initiate programmed replacement when necessary. This increases the useful life of the fluid and prevents damage caused by its degradation. When external replacement of the fluid is unavoidable, this can be programmed to coincide with normal maintenance schedules, thanks to the predictive options of this new monitoring system. The consortium will develop fibre-optic sensors using pilot lights, as well as alternative optical and electrochemical sensors for monitoring the fluid. It will also research and select different water separation and elimination techniques. The chosen approach involves a balanced risk strategy that combines tried and tested techniques with cutting-edge research. The impact of the system will be felt far beyond the partners making up the consortium: the cost savings for airlines as a result of the optimised maintenance strategy will give European aircraft makers a competitive advantage that will strengthen the whole aeronautical industry.