Boeing drops engine chevrons from 777X design amid ongoing certification

Petter Hörnfeldt, a B737 MAX pilot with Ryanair, explains that "engines with chevrons look very aerodynamic," but they actually reduce thrust by about 0.5%. Despite this loss, Boeing continued using chevrons as they allowed for reduced sound insulation on aircraft.

For the B777X, Boeing is opting for a different approach. Terry Beezhold, chief project engineer for the B777X, stated that "we are replacing the chevrons with a new nozzle design technology." This design provides equivalent noise reduction without adding weight or drag.

Jon Ohman, a chief test pilot for the GE9X engine used on the B777X, added that new materials allow them to meet acoustic requirements without a drag penalty. Safran has further enhanced noise reduction by applying honeycomb acoustic treatment and drilling holes in the composite skin of the GE9X exhaust system.

The GE9X engine has been tested extensively since 2016 and features advanced technologies aimed at optimizing performance while minimizing environmental impact. It is currently undergoing certification testing alongside the B777X under extreme conditions.

The GE9X is notable for its size and power. It achieved record-breaking thrust during ground tests in 2017 and is considered one of the most powerful engines ever made. Its list price is estimated at $45 million per engine.

Emirates has placed significant orders for these engines as part of their purchase of Boeing 777-9s, highlighting their investment in this advanced technology despite potential costs.