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The new noise protection hanger on the maintenance apron at Geneva Airport has allowed engines fitted to aircraft with wing spans up to 36 m to be tested without excessive noise load on the surrounding facilities and neighbours since 2016. These stationary engine tests are specified for certain types of maintenance tasks and cover the complete engine output range up to full thrust. During this work, the aircraft is restrained against moving in the hangar by special chocks.

The location of the new building was specifically chosen so that the adjacent workshop would screen off some of the noise. The hangar fully surrounds the aircraft on three sides but must have openings in the longitudinal direction to supply the engines with air: 22 vertical, circularly curved lamellae in the rear wall ensure that the air entering the hangar flows parallel to its longitudinal axis, is low-turbulence and without any potentially damaging crosswinds or vortices. The lamellae, like the rest of the ­interior surfaces of the hangar, are clad in glass-wool-filled perforated metal cassettes to insulate and absorb the sound.

The front of the hangar has a box-shaped roof extension to accommodate the vertical stabiliser on the aircraft’s tail. To minimise the escaping sound, this tail box has a folding door. A 46 m long hydraulically operated deflector shield can be raised or lowered in front of the building for the period of the engine tests. When inclined at 45°, the shield reduces noise and directs the hot gases vertically upwards.