Bleed systems decrease pressure and temperature to levels acceptable for downstream pipes and air cooling system. Bleed valves, regulating the pressure, have a strong safety issue: their failures can lead to aircraft depressurisation with the immediate request to land to the closest airport. In addition to all direct consequences on passengers/crews comfort, flight delay and traffic management, failures have a strong economic impact on airliners: a diversion is estimated to 150 000. In 2004, 10 diversions, consecutive to valves failure, have been reported for the AIRBUS fleet. Valve failures, resulting of ball bearings blockage, are due to fretting and false Brinelling, known to occur in quasi-static assemblies in vibratory environment.
Due to the power in crease of new aircraft engines and the extended service life of existing aircraft, vibration levels around engines are becoming extremely strong (about 25g). Temperatures can also reach up to 550°C. Systems surrounding engine zones are therefore submitted to new and extreme environmental constraints. Even if the tendency is to develop more electrical aircraft, most of the aircraft developed today, based on bleed systems, will still be in use in the next 20 years and their issues have to be solved. Today, bearings design and materials have reached their limit.
In order to propose innovative solutions answering the new requirements, BEARINGS need to:
i) better understand the degradations encountered, using recent advances in contact modelling
ii) propose innovative materials (bulk, smart sintered, nano materials) and adapted processes,
iii) propose relevant bearings designs.
In the competition with United States (and Japan for bearings suppliers), BEARING is a unique opportunity to maintain European Air Systems and Bearings suppliers leadership by offering a superior and affordable European technology, which supports an invaluable strategic advantage for European air-framers and airliners.
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