June 30, 2025, © Leeham News: GE Aerospace developed a huge engine for the Boeing 777X, the most powerful engine ever created. The GE9X tops out at 115,000 lbs of thrust.

The giant GE9X engine for the Boeing 777X generates 115,000 lbs of thrust. The human scale of the engine is illustrated here at a display at the Paris Air Show. Credit: Leeham News.

It’s had its development challenges. The 777-9, the first of the X family, was supposed to enter service in early 2020. Technical issues with the GE9X required removal of the engines from the test airplanes and a return to GE for fixes. This delayed flight testing by nine months. By then, certification of the 777X got caught up in the Boeing 737 MAX crisis; the 777X still is awaiting certification, which parties hope will come this year. Deliveries are now expected to begin next year.

Tim Clark, the president of Emirates Airline, has 205 Xs on order, more than any other customer, out of 521 in total. He’s publicly complained about the initial test results of the GE9X and demanded engine maturity before he’ll accept delivery.

GE has used the six year delay in the program to attempt to satisfy this demand.