Can an Engine Be Too Powerful? The 777X Problem

The Boeing 777X was meant to be the crown jewel of long-haul aviation. Stretch a 777, bolt on folding wingtips, strap on the biggest jet engines in history, and watch the orders roll in. But then reality intervened, and it turned out that when you build an engine the size of a small house, you also inherit small-house-sized problems.

Enter the GE9X. This turbofan is absurd even by aviation standards. The fan diameter is 134 inches, wider than the fuselage of a 737. It produces 105,000 pounds of thrust. Each engine is so large that when fitted, the 777X looks like a plane that wandered into a Photoshop exaggeration.

And yet, during early testing, engineers found cracks forming on components inside the engine, including parts of the stator vanes and thrust transfer structures designed to channel all that power into the aircraft itself. In other words, the GE9X was quite literally straining under its own strength. A supercar is only impressive until it snaps an axle at the traffic lights.

This contributed to the string of delays that have pushed the 777X’s entry into service back by years. Boeing originally planned to deliver it in 2020. Now 2025 is the best-case scenario, assuming nothing else cracks, stalls, or folds in the wrong direction. The world’s airlines have been forced to make do with older long-haul jets, while Boeing gets dragged into congressional hearings about quality control and regulatory patience wears thin.

So, can an engine be too powerful? In theory, no. Jet engines are designed with safety margins that make them overbuilt by default. But when you scale up to “largest ever,” you test the limits of materials, aerodynamics, and manufacturing. The GE9X uses carbon-fibre fan blades, ceramic matrix composites, and bleeding-edge cooling technology. It is a showcase of engineering, but also a reminder that the laws of physics and the realities of supply chains do not bend just because the marketing department wants “world’s biggest.”

The irony is that the GE9X has since gone on to set efficiency records. It is quieter, burns less fuel, and emits fewer pollutants than the engines it replaces. Once the wrinkles are ironed out, it will likely be a success story. But the delays have left Boeing nursing its reputation, airlines waiting far longer than expected, and passengers stuck on aircraft designed in the 1990s.

So maybe the lesson is this: an engine can’t be too powerful, but a programme can be too ambitious. And if history is any guide, the only thing harder than building the biggest jet engine in the world is convincing the flying public that everything is going exactly to plan.