LORDHASRECEIVED US certification for its NVX active noise-and-vibration control system on the McDonnell Douglas DC-9 and MD-80. The company says that its system is the first to be approved for use on large commercial aircraft, and "...is being considered for several DC-9/MD-80 installation programmes." Approval follows installation of the NVX on a corporate MD-87.

The system consists of actuators on the engine-mounting yoke which counteract engine vibration and so reduce cabin noise. The actuators are driven continuously by a controller based on cabin-noise data from microphones installed behind the trim or under the floor.

The results are most noticeable in the aft cabin, where engine tones typically measure 20dB above background noise, says Lord, adding: "The NVX Active System eliminates these tones on the ground, as well as during take-off, cruise and descent." Programme manager Becky Weih says that noise levels are so reduced that the rear of the cabin "...is no louder than the front". Erie, Pennsylvania-based Lord says the NVX has been approved on several corporate-aircraft types.

Source: Flight International