Boeing 777X Test Flights Paused… Again

Boeing 777X Test Flights Paused… Again

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The Boeing 777X is Boeing’s latest and (theoretically) greatest aircraft, which is eventually supposed to become the largest passenger jet in production. 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 now been pushed back until 2025.

Well, there’s now potentially yet another setback, as reported by The Air Current.

Engine mount issues ground Boeing 777X

In recent weeks, Boeing has resumed test flights with its 777X aircraft, as the aerospace giant works to get the airplane certified. On August 15, 2024, one of the 777-9 test aircraft with the registration code N779XY completed a 5hr31min test flight to & from Kona Airport (KOA).

The Boeing 777X’s test flight

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 with 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.

Here’s what a Boeing spokesperson had to say about this:

“During scheduled maintenance, we identified a component that did not perform as designed. Our team is replacing the part and capturing any learnings from the component and will resume flight testing when ready.”

Boeing 777X test flying has been paused

This isn’t good, but also isn’t terrible

On the one hand, the whole point of testing new aircraft is to figure out any issues before the planes are mass produced, and are in passenger service. So this largely seems like a routine aspect of getting new aircraft certified. Of course the concept of there being cracks in a part linking the engines and wing doesn’t sound good, but there’s a lot of redundancy to these systems.

It’s anyone’s guess how long it takes for this concern to be addressed, and for Boeing to continue flight testing.

I’d say the only reason this is actually significant news is that it will likely delay the 777X’s entry into service even more. We know that Boeing has been aiming to get the 777X certified in 2025, and to possibly even have the plane operating commercial flights before the end of next year.

It sure seems to me like that was an absolute best scenario timeline, assuming nothing else goes wrong during testing. Of course during flight testing stuff does go wrong, and that’s to be expected.

So personally I didn’t think the 2025 timeline for the 777X entering service was realistic, and I especially don’t think it’s realistic now. But maybe 2026 will be Boeing’s year?

Emirates desperately needs its Boeing 777Xs!

Bottom line

Test flights on the Boeing 777X have once again been paused, just weeks after they resumed. In this case, cracks were found in the thrust link during a routine post-flight inspection.

So we’ll see how long this pause lasts on Boeing’s part. For the sake of passengers, airline customers, and Boeing, hopefully this isn’t too big of a deal.

What do you make of these latest Boeing 777X issues?

Conversations (35)
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  1. Bill Bokeh Guest

    This series of incidents, disasters, in commercial, military and space sectors illustrates why the Boeing board had to pick someone out of retirement to take over the CEO position. I guess no one with a good résumé was willing to take on such a huge challenge and potentially ruin any future career, whatever the remuneration package may have been offered.
    To be followed.

  2. Barbarella Guest

    I wonder if it's a design fail or a raw material fail?

    Titanium supply lines are stretched thin with Russia under sanctions. Are counterfeit materials starting to make their way to aerospace ?
    Does anyone know about the frequency of actual material testing within the subcontractor chain ? How heavy is the reliance on material certificates, that are possibly fake ?

  3. Engel Gold

    Much ado about nothing.

  4. Jerry Wheen Gold

    I'm usually not worried about flying (and will take a 737-MAX nowadays). In case of the 777X I'll wait for several years of actual use by airlines until taking one of those.

    That's the difference: When the A380 was new, Lufthansa promoted those flights clearly during the booking process. With the 777X I wouldn't be surprised for that not to be the case.

  5. Malcolm Guest

    If it's Boeing, it ain't going!

    This is what happens when financial engineering takes over an aerospace company and you fire all the real engineers. MBAs who can speak to Wall St in their impenetrable language and probably went to Harvard with them, but have probably never been anywhere near the manufacturing hall or a testing ground.

  6. Pete Guest

    Yeesh, what an absolute dog of a project this airplane has turned-out to be. At this rate it will be 2030 before they deliver one to a customer.

  7. UncleRonnie Diamond

    I reckon Boeing bought cheap titanium to cut costs.

  8. Kevin Schunke Guest

    I am in Kona for the month of August. I have seen the plane numerous times, not only parked at the airport, but also on test flights. If you want to track on FlightRadar24, the call sign is BOE3.

  9. ted poco Guest

    All this Computer Aided Design and Simulation doesn’t seem to helping Boeing in catching these problems early.

  10. ConcordeBoy Diamond

    If this aircraft gets delayed beyond January 2027, then it will take the (13yr, 2mo) record time from launch-to-service from freakin' Concorde.

    That was a novel aircraft, designed with slide-rules more a half century ago, back before the first pocket calculator was ever even sold.

    ...this is a warm-over of a preexisting model, that had the benefit of computer assist.

    Dang Boeing sucks now. :(

  11. Ray Guest

    That sound you hear is the collective groan uttered by execs at Singapore Airlines and Cathay Pacific. Or it may be the cash counter at Airbus going brrrrr. I don’t know

    1. Pete Guest

      It's probably it's a combination of both. Airbus will certainly not be complaining, with 714 A350 orders awaiting fulfillment as of July this year.

  12. jcil Guest

    One of two things in my mind. Either Boeing severely under predicted what the loading conditions would be for this component in actual flight, or the part was manufactured with some of substandard titanium that is being (unknowingly?) used by suppliers.

    Boeing engineers should be able to scale up the loading on this part pretty well, but with their current lapses in judgement one can never tell. The fact that it totally failed (actually...

    One of two things in my mind. Either Boeing severely under predicted what the loading conditions would be for this component in actual flight, or the part was manufactured with some of substandard titanium that is being (unknowingly?) used by suppliers.

    Boeing engineers should be able to scale up the loading on this part pretty well, but with their current lapses in judgement one can never tell. The fact that it totally failed (actually broke on the one aircraft, not just cracked) at low hours and would have had to seen loads that even overwhelmed the safety factor built in is concerning. The substandard titanium is also concerning, as I would expect that Boeing would carefully monitor and inspect the new parts for the test aircraft. Also concerning that if it slipped into the 777X program, how much of this stuff is also getting into the production aircraft, not just at Boeing, but AirBus and others as well.

  13. EG Guest

    As someone working for Airbus: I'm happy that Boeing starts to be on the right track. Better be delayed but safe!

  14. Donato Guest

    Might we have reached a physical limit of how powerful an engine should be? I do realize this is not an engine fault but the engines should remain reliably attached to the frame.

    1. ConcordeBoy Diamond

      Except that this isn't even the most powerful engine on a commercial aircraft, just the largest.

      It produces significantly less thrust than the GE90-11Xs that have been on the 777-200LR and 777-300ER for well over 20yrs.

    2. Donato Guest

      I cede the point, you do have facts on your side.
      I wonder if some aspect of test flights pushed the thrust higher than specs specify. In any event this failure should not happen,

    3. ConcordeBoy Diamond

      What's scarier is that this didn't happen during the testing phase, it happened during certification. This thing's already been flying for 4.5yrs! Testing had already completed, this was supposed to be showing the FAA that everything is good to go.

      Yes, there were the MAX crashes (both of which occurred well before this aircraft's first flight) and the Pandemic (which struck the same month)...

      ...but still, even if we DOUBLE the testing+certification timeline of aircraft...

      What's scarier is that this didn't happen during the testing phase, it happened during certification. This thing's already been flying for 4.5yrs! Testing had already completed, this was supposed to be showing the FAA that everything is good to go.

      Yes, there were the MAX crashes (both of which occurred well before this aircraft's first flight) and the Pandemic (which struck the same month)...

      ...but still, even if we DOUBLE the testing+certification timeline of aircraft like the 777-300ER and A380, and apply it to this aircraft: 777X would have already been in service by the time this defect was discovered.

      Very disconcerting. But at least it's one good thing that the perpetual delays have turned up.

  15. Manny Guest

    Boeing needs a clean sheet design. This coincides with the new CEO taking over. So this might have been known to Boeing for a long, long time.

  16. Chris Guest

    When historians or MBA projects catch up with the industry, long delays like 777 by Boeing and new cabins by LH will be interesting studies.

    1. LEo Diamond

      And also how much did Lufthansa paid Skytrax

  17. Easy Victor Guest

    “ This isn’t part of the GE-9X engine that powers the airplane, but rather it’s a component designed by Boeing”

    “Designed by Boeing” seems to be the underlying problem that has enveloped that company. From actual design to maintenance, safety procedures, and quality control.

    1. AeroB13a Guest

      One has to agree with Easy, there is growing concern that Boeing engineers are either designing to fail or failing to design adequate failsafe systems into their aircraft. One has to wonder whether the corporate management is failing to employ suitable design engineers, alternatively and deliberately, allow margins of safety to be reduced to a minimum.

  18. MDHZ Guest

    I'm not an expert, but in the case of the thrust link, I don't agree with this sentence: "On the one hand, the whole point of testing new aircraft is to figure out any issues before the planes are mass produced, and are in passenger service."
    If the thrust link works reliable, and can take all the stresses, cannot be trial-and-error! ("Oh... we just found out through real-life testing that we made it too...

    I'm not an expert, but in the case of the thrust link, I don't agree with this sentence: "On the one hand, the whole point of testing new aircraft is to figure out any issues before the planes are mass produced, and are in passenger service."
    If the thrust link works reliable, and can take all the stresses, cannot be trial-and-error! ("Oh... we just found out through real-life testing that we made it too thin") This is so essential to the functioning of an airplane, that it has to be calculated and simulated again and again and again. And that the same weakness appears on a number of planes seems to indicate that they engineered it wrongly. I find this quite substantial, and would not put it in the "that's what test flights are for"-category.

    1. EG Guest

      Mechanical engineer here and I disagreed. Of course you can simulate again and again. But simulation only helps you simulate as far as you can simulate. Real-world testing and verification will validate that simulation and in this case it is not. I am not stress expert per se, but most of simulation on fatigue and fracture mechanics are based on 50 years old theory and being run on FE models.

    2. jcil Guest

      My experience as an engineer is that the issue with FE analysis on new products is not with the FE technique itself, but rather getting the loads to use and input to the computer analysis wrong. If the loads used are higher in the actual product, it will be at a higher risk of failure. Stress analysis and fatigue analysis are well understood by engineers, and especially at Boeing I would assume.

    3. EG Guest

      "Stress analysis and fatigue analysis are well understood by engineers, and especially at Boeing I would assume."

      That is only partially correct for isotropic and some composite material. I am not sure what kind of Titanium alloy it is, but sometimes the complexity within manufacturing and machining, different operational conditions, and materials specifications are hardly taken into account during simulation - so you might have deviations in the outcome even that the FE assumptions are...

      "Stress analysis and fatigue analysis are well understood by engineers, and especially at Boeing I would assume."

      That is only partially correct for isotropic and some composite material. I am not sure what kind of Titanium alloy it is, but sometimes the complexity within manufacturing and machining, different operational conditions, and materials specifications are hardly taken into account during simulation - so you might have deviations in the outcome even that the FE assumptions are correct.

  19. Nelson Diamond

    Quite sure Tim Clark is thinking at the moment about to switch all 777X to A350's.

    1. NSS Guest

      This was my question. What do airlines do if they need to retire planes and were counting on 777Xs to be able to do that? I assume 350/339 slots aren't easy to come by.

    2. Guest Guest

      They keep them up in the air for as long they need them (as long as they own it, if they lease it, then it's a different story!)

    3. Abdullah Guest

      Management teams will either lease out additional airframes from other carriers/partners or look to extend their own current leases on aircraft if the lessor agrees. It's not too bad of a situation unless your lessor isn't willing to budge or offer a viable rate; or there are no airlines with spare frames to loan out

  20. Scott Guest

    Curious why the testing is happening at KOA vs Seattle?

    1. neogucky Gold

      "KOA is a common location for Boeing for certain hot weather test conditions with plenty of empty airspace and clear weather conditions to support the flying and test points. Yuma, AZ is another location frequently used for hot weather testing conditions. Boeing then often goes to Fairbanks, AK or some airports in Canada for the cold weather testing."
      https://www.flyertalk.com/forum/travelbuzz/2166688-boeing-777x-kona-airport.html

  21. Exit Row Seat Guest

    Is it possible Boeing is pushing old technology too far. The original B777 entered service in 1995, some 30 yrs ago!!
    Again, Boeing went for the cheap and tried a NEO approach. Yet, it doesn't seem to be working too well as the original intro date for the "X" program was 2020?
    If they had gone with a clean sheet of paper, I think the jet would have been in the air right...

    Is it possible Boeing is pushing old technology too far. The original B777 entered service in 1995, some 30 yrs ago!!
    Again, Boeing went for the cheap and tried a NEO approach. Yet, it doesn't seem to be working too well as the original intro date for the "X" program was 2020?
    If they had gone with a clean sheet of paper, I think the jet would have been in the air right now. =:-)
    Mr Ortberg (new CEO of Boeing) has got his work cut out for him.
    Hope he can restore Boeing to it former status...good luck!!

    1. Scott Guest

      Pfft they're still trying to put more lipstick on the 1960's 737 pigs

Featured Comments Most helpful comments ( as chosen by the OMAAT community ).

The comments on this page have not been provided, reviewed, approved or otherwise endorsed by any advertiser, and it is not an advertiser's responsibility to ensure posts and/or questions are answered.

ConcordeBoy Diamond

If this aircraft gets delayed beyond January 2027, then it will take the (13yr, 2mo) record time from launch-to-service from freakin' Concorde. <i>That</i> was a novel aircraft, designed with slide-rules more a half century ago, back before the first pocket calculator was ever even sold. ...this is a warm-over of a preexisting model, that had the benefit of computer assist. Dang Boeing sucks now. :(

5
Chris Guest

When historians or MBA projects catch up with the industry, long delays like 777 by Boeing and new cabins by LH will be interesting studies.

5
MDHZ Guest

I'm not an expert, but in the case of the thrust link, I don't agree with this sentence: "On the one hand, the whole point of testing new aircraft is to figure out any issues before the planes are mass produced, and are in passenger service." If the thrust link works reliable, and can take all the stresses, cannot be trial-and-error! ("Oh... we just found out through real-life testing that we made it too thin") This is so essential to the functioning of an airplane, that it has to be calculated and simulated again and again and again. And that the same weakness appears on a number of planes seems to indicate that they engineered it wrongly. I find this quite substantial, and would not put it in the "that's what test flights are for"-category.

5
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