Why Do The Boeing 787’s Engines Have Chevrons & The 777X’s Don’t?

When the Boeing 747-8 Jumbo and 787 Dreamliner entered service in 2012 and 2015, respectively, engine nacelle chevrons appeared to be a technology of the future. It was one of the technologies that made the Dreamliner an innovative next-generation airliner, taking noise reduction to a new level. But 20 years later, the Boeing 777X is soon to enter service without them. It is an example of what appeared to be a future technology, but turned out to be more of a false start for the industry at large.