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Door blows out during ground test on Boeing 777X jet

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Door blows out during ground test on Boeing 777X jet

Old 12th Sep 2019, 07:29
  #101 (permalink)  
 
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Originally Posted by Smythe View Post
Boeing claims it had to stop the test...at which point did it stop?
Reportedly at 99% of target load.

Which, incidentally, is closer than Airbus got with the A380 wing test before being granted an exemption.

Boeing downplays impact of 777X load test "issue" - FlightGlobal
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Old 12th Sep 2019, 11:52
  #102 (permalink)  
 
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Wow, so maybe not really an issue. This is certainly different that a failure on the cabin pressure test which has been reported.
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Old 12th Sep 2019, 12:11
  #103 (permalink)  
 
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I assume that if this wasn’t a cargo or cabin door failure as suspected, then Boeing would say that this wasn’t a door failure.
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Old 12th Sep 2019, 12:31
  #104 (permalink)  
 
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According to Boeing's wording it happened during the "final load test" and it broke at 99 percent of whatever the goal was.
So what was the goal? Ultimate load? Limit load plus X? 1,3 max cabin pressure?
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Old 12th Sep 2019, 14:12
  #105 (permalink)  
 
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Originally Posted by Smythe View Post
Intermediate testing is done to weed out design and materials issues.

This was the FINAL ground test for certification...no learning here, this is to show the ac meets specs. It blew on the blow test and as Boeing stated, they had to stop the test.
The final test for cert is to show that all of the other testing and design assumptions have passed, and the ac is ready to be cert to fly.

This reads that they stopped the test before it was completed, correct?

On the blow test, there are 3 parts..static, working load, and ultimate.

Static tests the normal pressure
Working load tests the assumes highest pressure the fuselage will have ONCE in its service.
Ultimate load tests the working load by 1.5 times.

Boeing claims it had to stop the test...at which point did it stop?
The wording, failed under much higher that normal operations, stil could mean the working load test.

Think about it, if it had failed under ultimate, 1.5...that could be understood, because ultimate at 1.5 is the assumed failure pressure.

Given all of the secrecy, lack of disclosure, and other issues, I tend to believe it failed before working load....

As noted by the "ex-VP" videos are online and the ground testing was usually a media event....this one was closed doors to regulators. (and it failed with all of the regulatory agencies present, )

Time for Boeing to start telling the truth.
To who?

Boeing only needs to report details to the certifying agency and not to the public or its competitors

The customers need assurances that a any process affecting their delivery is being followed.

If adjustments are called for and approved by the FAA then that may be reportable to all.
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Old 12th Sep 2019, 14:27
  #106 (permalink)  
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To who?

Boeing only needs to report details to the certifying agency and not to the public or its competitors
This.

That fact that some information finds its way in the public realm does not suddenly compel an applicant or authority to explain or justify the outcome of a certification test. I've witnessed many certification tests, both as in interested person, and a delegate of the authority. Some of the tests were not a pass, and some test articles were broken - that's the nature of testing! If a structural element failed at 99% of its predicted ultimate load, hats off to the engineers! A little redesign, with apparently valid design assumptions, and the product should be great. We can hardly have efficient aircraft when the structure has a capacity many times the ultimate load cases - it'll be needlessly heavy.
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Old 12th Sep 2019, 22:18
  #107 (permalink)  
 
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Originally Posted by Pilot DAR View Post
This.

That fact that some information finds its way in the public realm does not suddenly compel an applicant or authority to explain or justify the outcome of a certification test. I've witnessed many certification tests, both as in interested person, and a delegate of the authority. Some of the tests were not a pass, and some test articles were broken - that's the nature of testing!
Exactly!!! Too many people on here seem to have forgotten why we test things. Cert test failures are not particularly uncommon (if normally less dramatic than a door blowing out). It got so bad on the 747-400 program that the FAA told Boeing to stop wasting their time - and that they would no longer witness certification flight testing unless Boeing had already performed an 'engineering test' to verify it would pass (doing a verification test before inviting the FAA was often SOP, but the 747-400 got so far behind schedule that they tried cutting out the verification testing and going straight to cert to save time).
I failed my first attempted certification test on the 747-8, even though we had done a verification test previously - the only time in my career I ever failed a cert test. We later determined that the problem was confined to specific OAT temperature band that we had been lucky enough (or unlucky - depending on you point of view) to encounter on the cert test - and it wasn't even my system at fault - it was the FMC. After reading my email to upper management informing them of the test failure, my supervisory pronounced me a 'Master of Understatement'
BTW, I flew a commercial flight out of Paine Field yesterday. I counted four completed 777-9X aircraft parked on the flightline (presumably without engines but from the angle I couldn't tell for sure).
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Old 13th Sep 2019, 08:06
  #108 (permalink)  
 
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Yes, still the old approach, What would pilots want to know about MCAS? What about structural integrity?
It should be a valid interest in a forum like this to want to find out more about what has happened aside from that carefully worded to downplay statement.
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Old 13th Sep 2019, 21:07
  #109 (permalink)  
 
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Originally Posted by pittsspecialguy View Post
Fifth, why does everyone want to be an aerospace engineer? Let the pros do their job and release the aircraft when they are ready. Yes, the MAX has issues but this is not related ....
It's quite possible that the MAX problems may be due in part to process problems inside Boeing. As such, the 777X trouble may very well be related.

Back when I was an 'aerospace engineer' at Boeing, the FAA did look at our processes as well as designs. But that was something Boeing management pushed back against. Perhaps that was a mistake.
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Old 13th Sep 2019, 21:23
  #110 (permalink)  
 
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Originally Posted by Pilot DAR View Post
. We can hardly have efficient aircraft when the structure has a capacity many times the ultimate load cases - it'll be needlessly heavy.
Well that's just silly hyperbole. Nobody is proposing that the structures handle 300% ("many times") of requirement. But we hope they will put a little bit of contingency in there. Maybe 110%. But the desperation to get it down to 100.001% of the requirement is what alas leads to this situation, where it fails at the 99% point. Which means, bluntly, it's a fail. And shows among other things overall poor design ability..

Originally Posted by lomapaseo
Boeing only needs to report details to the certifying agency and not to the public or its competitors
I'm afraid to tell you that if it goes on for much longer like this, where Chicago gives the heave-ho to anyone with a different opinion to theirs, or too much experience (= expensive), or any designer/supplier who is not the low bidder, it's going to get quite soon to the stage where Airbus, and soon the other up-and-coming competitors, are going to have forgotten more about aircraft design than the remaining staffers at Boeing ever knew. So no worries about what the competition might learn there. And very many of us would be really disappointed if that happened.

Last edited by WHBM; 13th Sep 2019 at 22:11.
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Old 13th Sep 2019, 21:52
  #111 (permalink)  
 
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Originally Posted by WHBM View Post
Well that's just silly hyperbole. Nobody is proposing that the structures handle 300% ("many times") of requirement. But we hope they will put a little bit of contingency in there. Maybe 110%. But the desperation to get it down to 100.001% of the requirement is what alas leads to this situation, where it fails at the 99% point. Which means, bluntly, it's a fail. And shows among other things overall poor design ability..
Not at all, there is still a safety factor, but if you make the safety factor bigger you waste fuel every hour the aircraft is flying. One of the ways the aircraft industry can get away with much smaller safety factors than other industries is the effort that goes into design verification and rigorous ongoing maintenance and inspection. However as an engineer who has used tools such as finite element analysis I find it astonishing that they seem to be able to routinely get within a few percent of the target for such complex structures. Can't help wondering if there is actually a little bit of smoke and mirrors in the details of how they load the structure to help ensure failure occurs at the target load.
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Old 14th Sep 2019, 06:08
  #112 (permalink)  
 
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From an ignoramus point of view, I'd be astonished if they couldn’t. A seasoned pilot can look at an artist's impression and know if it would work-eventually you get a feel for the hidden structural attributes if you have pondered a few Flight International cutaway diagrams. Eventually even a dumb pilot gets a feel for skin thickness, rib dimensions and spar depths. Modulus, strength, deflections, etc. , Aside from materials, not much is new since the B-47
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Old 14th Sep 2019, 08:39
  #113 (permalink)  
 
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Something else I am surprised no one has brought up.

The newer planes are designed to much finer tolerences, requiring precision machines to achieve those tolerences. Obviously the first few built for certification will receive more care to ensure that it is put together properly. But what happens when the planes go into production and become "mass produced"?

We have seen reports of Boeing accepting components for such newer planes that are not made according to specifications. When parts that were supposed to be computer cut were cut by hand. Where holes do not match up and have to be redrilled. Where parts that do not fit are hammered in to make them fit. https://www.sbs.com.au/news/sites/sb...ranscript.html

A carefully put together aircraft that fails at 99% highest test load may later become a bash-it-in-to-make-it-fit aircraft that fails at a much lower load .
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Old 14th Sep 2019, 09:22
  #114 (permalink)  
 
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MANY years ago, when I was designing inspection measurement equipment, a customer approached us to help him interpret an Airbus drawing. He dared not ask Airbus for clarification, because as a sub contractor he had been supplying the part for year(s) and feared opening an expensive can of worms. But none of my team could understand the drawing either, Airbus seem to have survived that one.
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Old 14th Sep 2019, 09:38
  #115 (permalink)  
 
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Some oddities in drawings nowadays are the result of using CAD tools. Some measurements sometimes are all but undecipherable.
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Old 5th Nov 2019, 08:03
  #116 (permalink)  
 
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Has there been any extra information released about this cargo door yet?

Have Boeing confirmed if it was a main cargo door or the bulk cargo door? They have been surpisingly tight lipped about this incident.

I think there is a much bigger problem than just a cargo door.
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Old 5th Nov 2019, 15:20
  #117 (permalink)  
 
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Originally Posted by Bootstrap1 View Post
Has there been any extra information released about this cargo door yet?

Have Boeing confirmed if it was a main cargo door or the bulk cargo door? They have been surpisingly tight lipped about this incident.

I think there is a much bigger problem than just a cargo door.
With such an all encompassing statement without evidence, you are in an excellent position to prove yourself right, no matter how small a newly found problem pops up.
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Old 27th Nov 2019, 16:07
  #118 (permalink)  
 
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Originally Posted by Bootstrap1 View Post
Has there been any extra information released about this cargo door yet?

Have Boeing confirmed if it was a main cargo door or the bulk cargo door? They have been surpisingly tight lipped about this incident.

I think there is a much bigger problem than just a cargo door.
Here is the evidence!
https://simpleflying.com/boeings-777x-ripped-apart/
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Old 27th Nov 2019, 16:36
  #119 (permalink)  
 
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Because the test was within 1% of its target pressure levels, the Seattle Times believes that the aircraft will not have to undergo a retest. While that might sound alarming to some, it’s important to remember that these pressure tests exert immense amounts of stress on the airframes, far more than would normally be encountered in a natural environment.
So, the prototype doesn’t meet the certification criteria. So why not let the certification criteria meet the prototype?
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Old 27th Nov 2019, 16:40
  #120 (permalink)  
 
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Add https and www. I can't post urls yet.

seattletimes.com/business/boeing-aerospace/boeing-777xs-fuselage-split-dramatically-during-september-stress-test
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