Equipped with a specially modified engine and packed with microphones and other sound-measuring equipment, this 777-300ER aircraft—the Quiet Technology Demonstrator Two—was the focus of a remarkable collaborative 2005 research and development program. The ultimate goal: to reduce cabin and community noise to the point where it is no longer an issue for passengers or people who live near airports. To combat the sound of jet-blast from the rear of the engine, Boeing, General Electric, and NASA developed serrated edges called chevrons for the back of the nacelle and the engine exhaust nozzle. The chevrons reduce jet blast noise by controlling the way the air mixes after passing through and around the engine.