Boeing 777X Test Flights Resume… Let’s Cross Our Fingers!

The 777X is Boeing’s latest and (theoretically) greatest aircraft, which is eventually supposed to become the largest passenger jet in production. Over 500 of these aircraft have been ordered by over a dozen airlines.

The catch is, the plane has experienced some major certification issues — while the plane was supposed to start commercial service in 2020, that timeline has been pushed back by several years. There’s now at least a little bit of positive news when it comes to the certification process for this aircraft.

Boeing 777X test flights resume after engine mount issues

In the summer of 2024, Boeing was aggressively performing test flights with its 777X aircraft, as the aerospace giant worked to get the airplane certified. Unfortunately those test flights came to a halt on August 15, 2024, as a major issue was discovered after a test flight. Specifically, one of the 777-9 test aircraft with the registration code N779XY completed a 5hr31min test flight to and from Kona Airport (KOA).

During a routine post-flight inspection, the failure of a crucial piece of structure that mounts the engine of the aircraft was discovered. Upon inspecting the other test aircraft, two other planes were found to have the same cracks, prompting a halt in test flying.

Specifically, the part that had the issue is the thrust link, which is a titanium component that transfers the thrust of the engine to the airframe. This isn’t part of the GE-9X engine that powers the airplane, but rather it’s a component designed by Boeing. Each engine has two of these, for redundancy.

One of the unique things about the 777X is its engines, which are the largest engines on any commercial aircraft. They weigh around 11 tons each, and have a diameter of over 11 feet.

So for over five months, Boeing had paused test flights with its new aircraft, which also pushed back the expected first delivery of the jet from 2025 to 2026.

There’s now a positive update, at least. On January 16, 2025, Boeing resumed 777X test flights. The same exact aircraft that operated the test flight in August 2024, operated a 2hr11min test flight to and from Boeing Field Airport (BFI).

Let’s hope the 777X enters service in 2026

Of course aircraft manufacturers perform extensive test flights for good reason, to work out any kinks or issues before the planes enter service. First and foremost, this is about safety. But on top of that, it’s less costly to discover issues before aircraft are mass produced and in service.

Given Boeing’s history, the focus needs to be on doing things slowly and correctly, rather than speeding through things. However, I think it goes without saying that airlines are desperately hoping that the testing goes smoothly from hereon out, and that certification of the jet happens some time in 2025.

With the latest pause in testing, the delivery timeline for the first 777X was pushed from 2025 to 2026. Many airlines are relying on Boeing’s ability to get this jet certificate in order to be able to execute their fleet plans, since Boeing has been having delivery delays with just about all of its aircraft.

For passengers, the Boeing 777X is a really exciting plane, given that many airlines plan to introduce new cabin concepts on these aircraft. Airlines like Cathay Pacific, Emirates, Qatar Airways, etc., are all desperate to add these planes to their fleet.

Bottom line

In August 2024, the Boeing 777X certification process faced a major setback, when test flights had to be paused. Over five months later, we’ve finally seen these flights resume, which is a positive development. The 777X is now expected to be delivered to airlines as of early 2026. For the sake of passengers, airline customers, and Boeing, I hope that timeline sticks.

When do you think the Boeing 777X will actually enter service?