The Boeing 777X incites a lot of emotion for people within the aviation community. For some, it is simply a figment of the imagination, as it has not had any meaningful introduction to service due to continuous delays. For others, the 777X creates excitement, as it is poised to be one of the largest airliners on the market when it enters service, outfitted with some truly unique design components. One of those components is the aircraft’s massive engine.

The GE9X engine chosen for the 777X airframe is an impressive product of American engineering, but it has been at the forefront of 777X concerns in recent months. Many of the negative headlines attached to the 777X and its engine are ultimately expected during the certification process of a new aircraft, as these processes are rightfully strict. Before further disregarding the 777X after more delays, it is important to understand exactly what has been going on with its engine and how it might not be a signal of a doomed aircraft, but rather a testament to aviation safety.

Development Timeline So Far

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Boeing formally launched the 777X program in 2013 as the next-generation widebody positioned to ultimately replace older aircraft in the Boeing 777 family and compete with other airliners, such as the Airbus A350. Initial development was defined by new features like composite wings with folding wingtips and a wider, more efficient airframe. Multiple prototypes and test airframes were built throughout the early development years as Boeing refined its assembly processes in Everett, Washington, and prepared for flight testing. The original target date for official entry into service was 2020.

This target date was not met, and the aircraft eventually made its first flight on January 25, 2020. By this time, Boeing had amended its target first delivery date to 2022. But this target was short-lived as well. Structural issues discovered during flight testing, lingering supply-chain pressures from the pandemic, and rigorous regulatory oversight highlighted a series of technical and production challenges that pushed back key certification objectives. Flight testing continued through 2024, punctuated by test fleet groundings and incremental fixes, as Boeing worked with the FAA on a comprehensive certification campaign spanning multiple phases.

As of early 2026, Boeing is preparing to fly the first production-standard 777X flight in April, but the program remains significantly behind its initial schedule. Entry into service has repeatedly slipped, with first deliveries now expected in 2026 or more likely 2027, seven years later than the original plan. Planned freighter variants of the 777X have also had development timelines pushed into the late 2020s. These persistent delays have resulted in substantial development costs and strained relations with major customers like Lufthansa and Emirates, who are adjusting fleet plans around the evolving timeline.

The GE9X

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From an engineering perspective, the 777X is an exciting aircraft full of a lot of advanced components. Aside from its unique folding wingtips, the aircraft boasts some truly massive engines that make the 777X immediately identifiable. The GE9X is a high-bypass turbofan engine derived from the GE90. The new derivative is larger, incorporates more ceramic-matrix composites, and was designed to be 10% more fuel efficient. When it received its FAA type certificate on September 25, 2020, the GE9X officially became the largest and most powerful commercial aircraft engine ever built.

To put this world-record engine into perspective, key design specifications are listed in the table below. There are 16 fan blades, each with a steel leading edge and fiberglass trailing edge, a design that better absorbs the impact of bird strikes than full-carbon fiber blades. This is an increased concern for an engine with such a large cross-sectional area; the GE9X is wider and taller than the fuselage of a 737. Reducing the total fan blade count down from 22, as on the GE90, results in a lighter, more aerodynamically efficient engine as well.

The above takeoff thrust number is what the FAA officially certified the engine for. In testing, the GE9X reached 134,300 pounds of thrust, setting a world record. Complementing its brute strength, the GE9X is a FADEC engine, meaning it is automatically optimized for best performance without the need for manual input. The 777X is a massive aircraft, and the purpose-built GE9X shares the same spirit.

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The Big Engine Has Posed Some Challenges

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GE knew it was taking on a big challenge when it won the 777X engine contract. An engine of this size was unprecedented, and it had to comply with an entirely new aircraft being designed simultaneously by Boeing. Before its FAA certification, GE Aviation was required to do further internal testing after an anomaly was detected in data from the high-pressure compressor. The issue was addressed and ultimately fixed, and the engine was certified a year later.

The real issues with the GE9X began to arise when it was fitted to the 777X prototypes and began flying. The timeline below presents the key issues experienced since 2020, with each new issue often resulting in the grounding of all test flights for a period of time. Most recently, Boeing CEO Kelly Ortberg disclosed a potential durability issue in the company’s Q4 2025 earnings call. Reuters and Bloomberg report that GE and Boeing will conduct an internal investigation into the engine seals. While no further information has been provided, should the issue be severe, a redesign of the problematic component may be required.

Certifying A New Airliner Isn’t Easy

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The issues experienced by the 777X program are partially indicative of an increased level of scrutiny within the US aviation industry, and especially towards Boeing. The two fatal crashes of the 737 MAX in 2018 and 2019 revealed significant shortcomings within Boeing’s internal processes and resulted in a much stricter recertification pathway for the 737 MAX. These heightened levels of scrutiny from the public and regulatory agencies are being applied to the 777X as well. Amid its program delays, which are not entirely unexpected for a new aircraft of this scale, the 777X has lost favor with many in the aviation community. Program delays have also now cost Boeing nearly $15 billion in penalties, as entry into service dates are routinely pushed back.

While the picture may look grim for the 777X, it is not necessarily a bad thing. After all, an even higher regulatory and safety standard is a good thing. Delays may be frustrating, but if Boeing has learned anything over the last ten years, it is always worth taking some more time to address any safety/certification concerns. It is certainly frustrating for airlines that expected the 777X to be delivered already, and rightfully so, but if more time is needed to ensure a safe aircraft enters the market, that is priceless.

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Who Has Ordered The 777X?

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Lufthansa was the first airline to order the 777X when it placed an order for 34 777-9 aircraft in September 2013 (later revised to 20 firm orders and 14 options). An additional order was placed later for some 777-8 freighter variants to be added to the Lufthansa Cargo fleet. While Lufthansa is the launch customer, it is the Middle Eastern airlines that make up the vast majority of 777X orders. As of November 2025, Emirates leads the way with 270 aircraft on order, followed by Qatar Airways with 124. Third place is held by Cathay with 35 aircraft on order. Notably missing from the 777X order list are the major US airlines, United Airlines, Delta Air Lines, and American Airlines. This is mostly a result of their network strategies, which consist of multiple hubs located across the country (and the world) that facilitate increased capacity via increased frequency.

Looking Forward

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The future of the 777X will no doubt be interesting. It is scheduled for its first production-standard flight in April of this year, and many parties will be eager to see how that goes. What is known, however, is that the 777X is slated to be an extremely capable aircraft thanks to its massive GE9X engine. Should the aircraft enter service in 2027, it will certainly turn heads. All that can be done in the meantime is what the aviation world has been doing since 2020: wait. With each setback, Boeing and GE alike feel more obligated to deliver. As an interested onlooker in the aviation community myself, I’m rooting for Boeing to get it right.