The Boeing 777X Concept Feature That Was Actually Never Developed

The Boeing 777X Concept Feature That Was Actually Never Developed
The Boeing 777X, the manufacturer’s highly anticipated next-generation widebody, has been undergoing certification testing since early this year. With the fourth test aircraft now in the air, Boeing leadership recently reaffirmed its confidence that certification will be completed in 2024, paving the way for the first delivery to launch customer Lufthansa in 2026.
However, the 777X program has faced significant delays and interruptions in flight testing, which have shaken market confidence and prompted strong reactions from airlines. Some carriers have even threatened to cancel orders, putting Boeing’s long-term strategy for the widebody market at risk as competitors respond to the uncertainty.
A Feature Left Behind: Engine Chevrons
One notable feature that will not be part of the 777X is the engine chevron—a design element that was included in the aircraft’s original concept but ultimately abandoned before production. Engine chevrons, the distinctive jagged “teeth” at the rear of many modern jet engines, are absent from all four 777X test aircraft.
What Are Engine Chevrons?
Engine chevrons are sawtooth-shaped structures on the edges of jet engine nacelles or nozzles. Developed through a collaboration between Boeing, General Electric (GE), and NASA over two decades ago, chevrons were first tested on a Boeing 777-300ER in 2005 as part of the Quiet Technology Demonstrator program.
Their primary purpose is noise reduction. Jet engine noise largely results from the turbulent mixing of hot exhaust with cooler outside air. Chevrons help smooth this mixing, reducing turbulence and, consequently, noise—especially during takeoff and landing. Tests have shown that chevrons can lower fan noise by up to 15 decibels in the forward cabin and on the ground.
It’s important to note that engine nacelles, which house the engine and its components, are considered part of the aircraft’s airframe rather than the engine itself. While Boeing and GE both hold patents on chevron technology, the decision to include them rests with Boeing’s design team.
Where Are Chevrons Used Today?
Engine chevrons made their commercial debut in 2006 with the unveiling of the Boeing 787’s engines. The GE GEnx engine, which powers most 787s and the Boeing 747-8, features chevrons, as does the competing Rolls-Royce Trent 1000 engine used on over 500 787s.
The Boeing 737 MAX series also incorporates chevrons on its CFM International LEAP-1B engines. This design choice was aimed at reducing noise to improve passenger comfort and meet stricter airport noise regulations, reflecting Boeing’s broader commitment to quieter, more environmentally friendly aircraft.
Looking Ahead
Despite the 777X’s delays and the omission of engine chevrons from its final design, Boeing remains focused on completing certification and delivering the aircraft to customers. The challenges faced by the program have underscored the competitive pressures in the widebody market and the importance of technological innovation—not just for performance, but also for meeting evolving regulatory and customer expectations.

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