Messier-Dowty is preparing to test noise-reducing components for its Airbus A340 landing gears as part of the European SILENCER noise-reduction programme. Add-on fairings have been designed for the nose, centre and main landing gear of the A340-300, says Messier-Dowty research and technology director Patrick Monclar.

Manufacture of the fairings is expected to start later this year, and retraction tests will be performed on Airbus UK's ironbird landing-gear systems test rig at Filton. The fairing designs have been evaluated for noise reduction by computational fluid dynamics (CFD) analysis at Germany's DLR research institute, while flight tests to compare noise to a standard configuration are planned for September 2003 on Airbus's A340 testbed, says Monclar.

In parallel, noise-reduction features that could be incorporated into future landing-gear designs are being investigated for all aspects of the gear, including wheels, brakes, tyres and doors. Attachment points, gear bay size and shape, and bay door size and shape have been identified as areas where changes would not compromise gear functionality. The design work will culminate in tests in the German-Netherlands DNW windtunnel in late 2004.

The €110 million ($111 million) SILENCER project is 50% funded by the European Commissionunder its Fifth Framework initiative. Co-ordinated by Messier-Dowty parent Snecma Group, it consists of 51 partners representing 16 countries. The four-year programme was launched in April 2001, and it is hoped that the technologies developed could reduce aircraft noise 3dB by 2006 and 6dB by 2008. Monclar says that after successive reductions in aircraft engine noise, landing gear now causes 25% of aircraft noise on approach and landing.

Source: Flight International