Boeing's Engine Chevron Designs Trade Noise Reduction for Added Drag

Boeing uses serrated engine-nozzle edges, known as chevrons, on the 737 MAX, 747-8 and 787. The 787’s Rolls-Royce Trent 1000 and GE GEnx engine options both use the feature. The 777X’s GE9X nozzle omits chevrons.

Key details

• Boeing worked with General Electric and NASA on chevron development.
• An aviation commentator, Petter Hörnfeldt of Mentour Pilot, estimated that chevrons can reduce thrust by about 0.5%.
• The 787’s quieter engines reportedly allowed Boeing to remove up to 600 pounds of acoustic insulation.
• The GE9X nozzle system was reported to weigh about 20% less than older designs.
• Airbus did not adopt chevrons on the A350 or A320neo family, according to the report. A350 Chief Engineer Dougie Hunter said the fuel-consumption cost outweighed the noise benefit.

The 787’s quieter engines reportedly let Boeing remove up to 600 pounds of acoustic insulation.

Why it matters

Chevron edges help reduce engine noise by shaping how exhaust mixes with surrounding air. The 777X’s GE9X illustrates a different approach: its nozzle design reduces weight without using chevrons.