Why Boeing's Quieter Engines Carry A Penalty No Airbus Aircraft Accepts

Boeing’s quieter engine “chevrons” won’t be part of the company’s next step in widebody design. NASA developed the jagged, serrated nozzle idea after work starting in 2001, when experimental engines on a modified Learjet 25 were flight-tested. NASA says early results showed only a 0.25% thrust reduction, while helping cut jet noise for communities. Boeing used the technology on the 787 and later applied related chevron concepts to aircraft updates such as the 747-8, 737 MAX and 777X. But the 777X has moved on from chevrons, while Airbus skipped them entirely—leaving Boeing unlikely to revert.