musman9853
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Re: Boeing 777X Testing Thread - 2019

Fri Sep 20, 2019 1:36 am

kanban wrote:
Part of the testing involves cycling the fuselage pressure up and down hundreds of times looking for stress/fatigue issues. doing the highest pressure test first destroys all that information. like bending the wings to failure on the first test..... now you need to build another set of wings and install them, however you would have a bastard airframe and anything found on subsequent cycle testing would always be in doubt as to whether it was a basic frame issue or a repair frame issue.

there may be no design failure here, but a manufacturing plan or sequence issue, say something simple like a failure to de-burr the lock attach holes.

Anyway this will all be resolved before the repaired engines arrive.


isn't there a separate fatigue test airframe being built though?
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JayinKitsap
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Re: Boeing 777X Testing Thread - 2019

Fri Sep 20, 2019 2:12 am

musman9853 wrote:
kanban wrote:
Part of the testing involves cycling the fuselage pressure up and down hundreds of times looking for stress/fatigue issues. doing the highest pressure test first destroys all that information. like bending the wings to failure on the first test..... now you need to build another set of wings and install them, however you would have a bastard airframe and anything found on subsequent cycle testing would always be in doubt as to whether it was a basic frame issue or a repair frame issue.

there may be no design failure here, but a manufacturing plan or sequence issue, say something simple like a failure to de-burr the lock attach holes.

Anyway this will all be resolved before the repaired engines arrive.


isn't there a separate fatigue test airframe being built though?


The static frame was first off of the line, then the fatigue frame. It is out in the back yard being pushed and pulled.

http://robedgcumbe.com/fatigue-777x-in-the-test-frame/
 
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Re: Boeing 777X Testing Thread - 2019

Sat Sep 28, 2019 11:20 am

L/N 1605, 777-9, WH006, future Emirates A6-EZD out of the Everett paint hangar, September 26th 2019.

Image

Original uploaded by Matt Cawby at twitter, see : https://twitter.com/mattcawby/status/11 ... 2698505216
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fcogafa
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 2:13 am

Two GE9X engines were delivered to Paine Saturday evening on an An124
 
Scotron12
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 4:57 am

fcogafa wrote:
Two GE9X engines were delivered to Paine Saturday evening on an An124


Hard to decide what to believe with no official word from Boeing or GE.

You would think this news is something Boeing/GE would want shouted from the rooftops!!
 
kengo
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 5:18 am

Scotron12 wrote:
fcogafa wrote:
Two GE9X engines were delivered to Paine Saturday evening on an An124


Hard to decide what to believe with no official word from Boeing or GE.

You would think this news is something Boeing/GE would want shouted from the rooftops!!


A tweet from Chris Lee....

https://twitter.com/propandkerosene/sta ... 1076795392
 
OmerMaz
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 6:11 am

kengo wrote:
Scotron12 wrote:
fcogafa wrote:
Two GE9X engines were delivered to Paine Saturday evening on an An124


Hard to decide what to believe with no official word from Boeing or GE.

You would think this news is something Boeing/GE would want shouted from the rooftops!!


A tweet from Chris Lee....

https://twitter.com/propandkerosene/sta ... 1076795392


So...the 777X testing will resume soon as expected?
 
Scotron12
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 7:13 am

OmerMaz wrote:
kengo wrote:
Scotron12 wrote:

Hard to decide what to believe with no official word from Boeing or GE.

You would think this news is something Boeing/GE would want shouted from the rooftops!!


A tweet from Chris Lee....

https://twitter.com/propandkerosene/sta ... 1076795392


So...the 777X testing will resume soon as expected?


I would assume so and that we will see 1st flight before end of year.

Guess the engine issue was a quick fix afterall and not some major issue that required a big retest period.
 
OmerMaz
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 7:32 am

Scotron12 wrote:
OmerMaz wrote:
kengo wrote:


So...the 777X testing will resume soon as expected?


I would assume so and that we will see 1st flight before end of year.

Guess the engine issue was a quick fix afterall and not some major issue that required a big retest period.



That what I was hopping for, a fix that won't be too drastic.
If she'll fly for the first time before the end of the year, Boeing clould at least achive type certification in 2020. They can do that with the whole barrage of frames they've got now.
 
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 8:37 am

Stitch wrote:
justloveplanes wrote:
Hmmm, so why run the extreme test in the first place?


Because it is part of the certification process - same reason they bend the wings to 150% of what they could ever possibly see in service. Modern modeling is likely accurate enough to do away with the 150% "cushion", but aviation is still a conservative discipline. :biggrin:


justloveplanes wrote:
If is to gain knowledge and get a certainty level about the reliability of the engine, then a stress test is good.


As I recall from the thread, the engine was only run at this level for around three hours.


justloveplanes wrote:
Question still remains, how do you validate the fix?


I would expect GE would continue to run their test-bed engine on the 747 / in the lab as well as closely monitoring the 777-9 test fleet as it gains hours.


( this is probably a "detail" question for Lightsaber!? )
There is a( strongly exponential) relation between increasing thrust and as a result decreasing service life.
3hours at nn% thrust above nominal shows that this assumed relation is met / exceeded.
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RickNRoll
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 12:25 pm

Everyone seems to be having coating problems. Perhaps if that all just shared a few trade secrets it would be better for everyone, including the flying public.
 
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 2:29 pm

Scotron12 wrote:
Guess the engine issue was a quick fix after all and not some major issue that required a big retest period.

Now you see the PR benefit of reducing expectations.

Yet we don't know what the fix is.

IMO it could easily be substitution of some conservative variant of the failing parts just to get the airframe test program rebooted, with the actual production fix to come later in the game.

Maybe some day we will know more.
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chiki
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 5:00 pm

Seems there is more activity on the 777x https://twitter.com/mattcawby/status/11 ... 97381?s=19

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Scotron12
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 6:10 pm

Apart from the engines, anything stopping 1st flight once engines installed??
 
ShamrockBoi330
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Re: Boeing 777X Testing Thread - 2019

Sun Sep 29, 2019 11:57 pm

[*]
Scotron12 wrote:
Apart from the engines, anything stopping 1st flight once engines installed??


Exploding doors?
 
Scotron12
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 12:44 am

ShamrockBoi330 wrote:
[*]
Scotron12 wrote:
Apart from the engines, anything stopping 1st flight once engines installed??


Exploding doors?


Very good...forgot that one! :banghead:
 
jagraham
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 12:59 am

Scotron12 wrote:
ShamrockBoi330 wrote:
[*]
Scotron12 wrote:
Apart from the engines, anything stopping 1st flight once engines installed??


Exploding doors?


Very good...forgot that one! :banghead:


Now that we know it happened at about 149%, maybe not. Should be a quicker fix than the stator vanes. Of course a quick fix will probably add a little weight which the 779 certainly does not need, but they can probably fly by the time the ground testing is complete.
 
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 7:13 am

jagraham wrote:
Scotron12 wrote:
ShamrockBoi330 wrote:
[*]

Exploding doors?


Very good...forgot that one! :banghead:


Now that we know it happened at about 149%, maybe not. Should be a quicker fix than the stator vanes. Of course a quick fix will probably add a little weight which the 779 certainly does not need, but they can probably fly by the time the ground testing is complete.


I also think this will be resolved by analysis, just like they did when the A380 static test failed before it reached the ultimate load.

The fact the corrected engines are now delivered to Seattle mens that the aircraft can rerun some functional tests on ground and then re-taxi and re-RTO before the first flight that could potentially happen in December or maybe earlier. Who knows?
 
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 12:44 pm

As I mentioned before, it depends a lot on how exactly the door failed (something we I have no information on). Assuming it's just a failed latch or hinge then it will be a simple fix by analysis.

It would only require physical re-testing if it had failed at a relatively low test load - but at 149% of max load it's close enough for them to justify almost anything short of a fundamental redesign.
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 12:50 pm

VV wrote:
jagraham wrote:
Scotron12 wrote:

Very good...forgot that one! :banghead:


Now that we know it happened at about 149%, maybe not. Should be a quicker fix than the stator vanes. Of course a quick fix will probably add a little weight which the 779 certainly does not need, but they can probably fly by the time the ground testing is complete.


I also think this will be resolved by analysis, just like they did when the A380 static test failed before it reached the ultimate load.

The fact the corrected engines are now delivered to Seattle mens that the aircraft can rerun some functional tests on ground and then re-taxi and re-RTO before the first flight that could potentially happen in December or maybe earlier. Who knows?


I think we would need more backgrounds. Just comparing to a different aircraft, different failure isn't enough. A thourough analyses of the failure should be in place, the failure modes, certification requirements, root causes. Was it shear, dynamic fatigue, deformation of the surrounding structure, different loadpatterns than referenced, maybe a even a manufacturing or assembly error. All should be objectively investigated and solutions be presented to the independent certification body.
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par13del
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 1:01 pm

keesje wrote:
I think we would need more backgrounds. Just comparing to a different aircraft, different failure isn't enough. A thourough analyses of the failure should be in place, the failure modes, certification requirements, root causes. Was it shear, dynamic fatigue, deformation of the surrounding structure, different loadpatterns than referenced, maybe a even a manufacturing or assembly error. All should be objectively investigated and solutions be presented to the independent certification body.

Do we have whistle blower reports or some other rumors that this is not taking place?
 
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keesje
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 1:16 pm

par13del wrote:
keesje wrote:
I think we would need more backgrounds. Just comparing to a different aircraft, different failure isn't enough. A thourough analyses of the failure should be in place, the failure modes, certification requirements, root causes. Was it shear, dynamic fatigue, deformation of the surrounding structure, different loadpatterns than referenced, maybe a even a manufacturing or assembly error. All should be objectively investigated and solutions be presented to the independent certification body.

Do we have whistle blower reports or some other rumors that this is not taking place?


I think investigations are going on "certification requirements", "root causes", "different loadpatterns than referenced" and "the independent certification body". https://www.businessinsider.nl/boeing-737-max-crisis-list-lawsuits-investigations-faces-faa-2019-5?international=true&r=US
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WIederling
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 1:17 pm

par13del wrote:
The 777X is still in testing, are we being technical?


I'd guess that ?most? ( or just a lot ) of certification work has already been done
concomitant with the design process.
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Spetsnaz55
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 1:30 pm

777x will fly in late October or November.

From what I heard
 
jagraham
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 1:34 pm

keesje wrote:
VV wrote:
jagraham wrote:

Now that we know it happened at about 149%, maybe not. Should be a quicker fix than the stator vanes. Of course a quick fix will probably add a little weight which the 779 certainly does not need, but they can probably fly by the time the ground testing is complete.


I also think this will be resolved by analysis, just like they did when the A380 static test failed before it reached the ultimate load.

The fact the corrected engines are now delivered to Seattle mens that the aircraft can rerun some functional tests on ground and then re-taxi and re-RTO before the first flight that could potentially happen in December or maybe earlier. Who knows?


I think we would need more backgrounds. Just comparing to a different aircraft, different failure isn't enough. A thourough analyses of the failure should be in place, the failure modes, certification requirements, root causes. Was it shear, dynamic fatigue, deformation of the surrounding structure, different loadpatterns than referenced, maybe a even a manufacturing or assembly error. All should be objectively investigated and solutions be presented to the independent certification body.


All true. But they can test fly around it. The FAA has to be satisfied before they do their final checks (FAA personnel flying the plane). In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.
 
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Stitch
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 1:39 pm

jagraham wrote:
All true. But they can test fly around it. The FAA has to be satisfied before they do their final checks (FAA personnel flying the plane). In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.


Since the failure happened at ~149% of limit load, there is no reason why they cannot pressurize the hold to normal values as they are well below the failure point.
 
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 1:56 pm

jagraham wrote:
In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.


That is an impossibility. The cargo hold is part of the hermetically unpartioned fuselage space.
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 2:02 pm

par13del wrote:
Do we have whistle blower reports or some other rumors that this is not taking place?

Nah, all we have is a FUD narrative: since MCAS was a FUBAR, everything else is too.

WIederling wrote:
jagraham wrote:
In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.

That is an impossibility. The cargo hold is part of the hermetically unpartioned fuselage space.

You can do all kinds of things pre-certification under experimental certificate.

Besides we have unpressurized ferry flights all the time.

It's far from impossible.
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jagraham
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 2:21 pm

Stitch wrote:
jagraham wrote:
All true. But they can test fly around it. The FAA has to be satisfied before they do their final checks (FAA personnel flying the plane). In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.


Since the failure happened at ~149% of limit load, there is no reason why they cannot pressurize the hold to normal values as they are well below the failure point.


Agreed.
 
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 2:50 pm

Spetsnaz55 wrote:
777x will fly in late October or November.

From what I heard


No disrespect, but do you have a source for that? Or is it just something someone you know said
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keesje
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 3:24 pm

Revelation wrote:
par13del wrote:
Do we have whistle blower reports or some other rumors that this is not taking place?

Nah, all we have is a FUD narrative: since MCAS was a FUBAR, everything else is too.

WIederling wrote:
jagraham wrote:
In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.

That is an impossibility. The cargo hold is part of the hermetically unpartioned fuselage space.

You can do all kinds of things pre-certification under experimental certificate.

Besides we have unpressurized ferry flights all the time.

It's far from impossible.


I remember first flight(s) of previous new passenger aircraft took hours, covered a lot of primairy testing and expanded the flight enveloppe quickly. A "look it can fly" first flight seems hardly desirable from a PR standpoint..
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OmerMaz
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 3:35 pm

Spetsnaz55 wrote:
777x will fly in late October or November.

From what I heard


Unless this is realiable and new, this is what Boeing said back in June before the engine problems began.
 
texl1649
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 3:50 pm

If the Antonov flights do in fact indicate the engines have been re-delivered, it's entirely reasonable to expect an October-November flight. It shouldn't take Boeing that much longer to hook everything back up again and get actual ground testing underway.
 
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 3:50 pm

keesje wrote:
I remember first flight(s) of previous new passenger aircraft took hours, covered a lot of primairy testing and expanded the flight enveloppe quickly. A "look it can fly" first flight seems hardly desirable from a PR standpoint..

I thought the whole point of all the certification issues was to ensure that we did not have test flights that were for PR purposes?
Is it that we do not want them to do things right?
 
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 3:51 pm

Stitch wrote:
jagraham wrote:
All true. But they can test fly around it. The FAA has to be satisfied before they do their final checks (FAA personnel flying the plane). In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.


Since the failure happened at ~149% of limit load, there is no reason why they cannot pressurize the hold to normal values as they are well below the failure point.


Hello.

Where is this 149% from? Is it official that this was the percent?
 
Opus99
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 4:24 pm

For a fix that quick, I take it that GE knew exactly what the problem was maybe they did it initially for some other benefits. And then found out it won’t work and then put Back the original plan
 
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 4:29 pm

FrenchPotatoEye wrote:
Where is this 149% from? Is it official that this was the percent?


It is from Official Boeing Press releases. They said it failed at 99% of Ultimate Load. Ultimate Load is 150% of Limit Load, so 99% of Ultimate Load would be 148-149% of Limit Load. Limit Load is the maximum load the airframe should ever experience in normal operations.
 
VV
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 4:38 pm

jagraham wrote:
keesje wrote:
VV wrote:

I also think this will be resolved by analysis, just like they did when the A380 static test failed before it reached the ultimate load.

The fact the corrected engines are now delivered to Seattle mens that the aircraft can rerun some functional tests on ground and then re-taxi and re-RTO before the first flight that could potentially happen in December or maybe earlier. Who knows?


I think we would need more backgrounds. Just comparing to a different aircraft, different failure isn't enough. A thourough analyses of the failure should be in place, the failure modes, certification requirements, root causes. Was it shear, dynamic fatigue, deformation of the surrounding structure, different loadpatterns than referenced, maybe a even a manufacturing or assembly error. All should be objectively investigated and solutions be presented to the independent certification body.


All true. But they can test fly around it. The FAA has to be satisfied before they do their final checks (FAA personnel flying the plane). In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.


They can fly it once the safety of flight clearance is obtained.
The static test failure happened at around 148% of the Limit load. It is not an issue for first flight and beyond.
 
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FrenchPotatoEye
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 4:42 pm

Stitch wrote:
FrenchPotatoEye wrote:
Where is this 149% from? Is it official that this was the percent?


It is from Official Boeing Press releases. They said it failed at 99% of Ultimate Load. Ultimate Load is 150% of Limit Load, so 99% of Ultimate Load would be 148-149% of Limit Load. Limit Load is the maximum load the airframe should ever experience in normal operations.


Ah I see. Many thanks Mr stitch :)

1 percent off limited load is ok. They will fixed it.
 
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 4:43 pm

FrenchPotatoEye wrote:
Stitch wrote:
jagraham wrote:
All true. But they can test fly around it. The FAA has to be satisfied before they do their final checks (FAA personnel flying the plane). In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.


Since the failure happened at ~149% of limit load, there is no reason why they cannot pressurize the hold to normal values as they are well below the failure point.


Hello.

Where is this 149% from? Is it official that this was the percent?


https://boeing.mediaroom.com/news-relea ... tem=130500

CHICAGO, September 10, 2019 – During final load testing of the 777X static test airplane, a test which involves bending the wings of the airplane up to a level far beyond anything expected in commercial service, an issue arose that required the team to suspend testing. The testing issue occurred during the final minutes of the test, at approximately 99 percent of the final test loads, and involved a depressurization of the aft fuselage.

The test team followed all safety protocols, and we are conducting a comprehensive root-cause assessment over the coming weeks. The static airplane has been successfully undergoing testing since June, and this was the final test for the static test article. While our root cause assessment continues, at this time we do not expect that this will have a significant impact on aircraft design or on our overall test program schedule. We remain fully focused on safety as our highest priority, as we subject the 777X to a rigorous test program prior to first flight.

So it was doing the final test after months of testing, taking it far beyond any level of commercial flight i.e. doing the 150% load test, where it failed at approx 99% of final test load thus 150%*.099 = 148.5% which some round up to 149%.

keesje wrote:
I remember first flight(s) of previous new passenger aircraft took hours, covered a lot of primairy testing and expanded the flight enveloppe quickly. A "look it can fly" first flight seems hardly desirable from a PR standpoint..

That is just the way you are choosing to characterize what the first flight would be.

As above, the only authoritative statement we have is the static load test issue is not expected to have a significant impact on overall test program schedule.

To me that suggests they do not need to hit the 150% load before first flight, or they have a path to a solution that will be in place by the first flight without impacting the overall test program schedule.

The whole "can they fly the plane unpressurized" is a red herring, IMO, but as far as I know one certainly can fly a plane on an experimental certificate without the cabin being pressurized.
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Opus99
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 4:59 pm

Also if we expect first flight in late October/early November, can we expect to see it at the Dubai air show or is that too soon?
 
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VirginFlyer
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 6:12 pm

Revelation wrote:
WIederling wrote:
jagraham wrote:
In the meantime, they certainly can fly without pressurizing the cargo hold if they want to get started.

That is an impossibility. The cargo hold is part of the hermetically unpartioned fuselage space.

You can do all kinds of things pre-certification under experimental certificate.

Besides we have unpressurized ferry flights all the time.

It's far from impossible.

It is impossible to do something which it is not capable of doing - in this case flying with just the cargo hold unpressurised. The cabin floor is not a pressure bulkhead, so it is all or nothing: whatever pressure differential you want the cargo hold at is the pressure differential the whole fuselage has to be pressurised at.

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Revelation
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 6:30 pm

VirginFlyer wrote:
Revelation wrote:
WIederling wrote:
That is an impossibility. The cargo hold is part of the hermetically unpartioned fuselage space.

You can do all kinds of things pre-certification under experimental certificate.

Besides we have unpressurized ferry flights all the time.

It's far from impossible.

It is impossible to do something which it is not capable of doing - in this case flying with just the cargo hold unpressurised. The cabin floor is not a pressure bulkhead, so it is all or nothing: whatever pressure differential you want the cargo hold at is the pressure differential the whole fuselage has to be pressurised at.

Glad to see a.net is upholding its high standard with regard to pedantry. Yes, it is a given that you cannot have "just the cargo hold unpressurized", but this is the 777x testing thread, and yes, you can find some worthwhile testing you can do if the cabin is unpressurized, the experimental certificate allows for this if you choose to do so.
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VirginFlyer
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 6:36 pm

Revelation wrote:
VirginFlyer wrote:
Revelation wrote:
You can do all kinds of things pre-certification under experimental certificate.

Besides we have unpressurized ferry flights all the time.

It's far from impossible.

It is impossible to do something which it is not capable of doing - in this case flying with just the cargo hold unpressurised. The cabin floor is not a pressure bulkhead, so it is all or nothing: whatever pressure differential you want the cargo hold at is the pressure differential the whole fuselage has to be pressurised at.

Glad to see a.net is upholding its high standard with regard to pedantry. Yes, it is a given that you cannot have "just the cargo hold unpressurized", but this is the 777x testing thread, and yes, you can find some worthwhile testing you can do if the cabin is unpressurized, the experimental certificate allows for this if you choose to do so.

You call it pedantry, I call it addressing a commonly held misconception that certain parts of the pressure vessel can be flown pressurised while other parts are not.

V/F
It is not for him to pride himself who loveth his own country, but rather for him who loveth the whole world. The earth is but one country, and mankind its citizens. —Bahá'u'lláh
 
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Revelation
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 6:47 pm

VirginFlyer wrote:
Revelation wrote:
VirginFlyer wrote:
It is impossible to do something which it is not capable of doing - in this case flying with just the cargo hold unpressurised. The cabin floor is not a pressure bulkhead, so it is all or nothing: whatever pressure differential you want the cargo hold at is the pressure differential the whole fuselage has to be pressurised at.

Glad to see a.net is upholding its high standard with regard to pedantry. Yes, it is a given that you cannot have "just the cargo hold unpressurized", but this is the 777x testing thread, and yes, you can find some worthwhile testing you can do if the cabin is unpressurized, the experimental certificate allows for this if you choose to do so.

You call it pedantry, I call it addressing a commonly held misconception that certain parts of the pressure vessel can be flown pressurised while other parts are not.

Fair enough. I apologize if I caused any confusion on the issue given I may have misunderstood the point being addressed in this thread.
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iamlucky13
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 9:03 pm

ShamrockBoi330 wrote:
[*]
Scotron12 wrote:
Apart from the engines, anything stopping 1st flight once engines installed??


Exploding doors?


I hope Boeing releases more information on the depressurization soon. Some rumors I heard would really drive home the point about not jumping to conclusions if they turn out to be true.

I'm not going to feed the rumor mill though. Just suggesting that everyone not get too attached to their pet theories on the cause and effects of the depressurization.
 
jagraham
Posts: 924
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 9:31 pm

keesje wrote:
VV wrote:
jagraham wrote:

Now that we know it happened at about 149%, maybe not. Should be a quicker fix than the stator vanes. Of course a quick fix will probably add a little weight which the 779 certainly does not need, but they can probably fly by the time the ground testing is complete.


I also think this will be resolved by analysis, just like they did when the A380 static test failed before it reached the ultimate load.

The fact the corrected engines are now delivered to Seattle mens that the aircraft can rerun some functional tests on ground and then re-taxi and re-RTO before the first flight that could potentially happen in December or maybe earlier. Who knows?


I think we would need more backgrounds. Just comparing to a different aircraft, different failure isn't enough. A thourough analyses of the failure should be in place, the failure modes, certification requirements, root causes. Was it shear, dynamic fatigue, deformation of the surrounding structure, different loadpatterns than referenced, maybe a even a manufacturing or assembly error. All should be objectively investigated and solutions be presented to the independent certification body.


Since it was a test, there would be several high speed cameras looking at the fixture. And the parts were recoverable without further damage.
Between the cameras and a few days with the failed parts under a microscope with some expert metallurgists looking at them, I am confident that Boeing knows what the failure mode is by now.
As others have said, it may be that the failure may be due to a combination of spec issues which caused the actual load to exceed 150% of design maximum. In which case the issue can be closed by analysis. Although I hope Boeing beefs up the latch and/or surrounding metal before long. Then goes back and makes the real fix. At least it can't amount to 22000 lbs of fixes like the wing glove fix for the 787.
 
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SEPilot
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Re: Boeing 777X Testing Thread - 2019

Mon Sep 30, 2019 10:53 pm

Isn’t the 777X pressurized to 6,000 ft, while the old 777s were only pressurized to 8,000 ft? If that is the case then it is not all that surprising that a door popped.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
 
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bikerthai
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Re: Boeing 777X Testing Thread - 2019

Tue Oct 01, 2019 1:35 pm

Revelation wrote:
Yes, it is a given that you cannot have "just the cargo hold unpressurized", but this is the 777x testing thread, and yes, you can find some worthwhile testing you can do if the cabin is unpressurized, the experimental certificate allows for this if you choose to do so.


SEPilot wrote:
Isn’t the 777X pressurized to 6,000 ft, while the old 777s were only pressurized to 8,000 ft? If that is the case then it is not all that surprising that a door popped.


Which is exactly the reason why you do not need to delay flight tests due to the decompression.

1) They can fly unpressurized if they maintain altitude of less than 14000 ft. (Not sure why would they do that, but I know you are allowed to do this by the regulations)

2) They can fly to 8000 ft. pressure altitude for many tests.

3) As long as they do not load the plane to max weight, the wing loading will never reach beyond the point where they decompressed during the test. The flight parameter will still meet the required regulations.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
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keesje
Posts: 13178
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Re: Boeing 777X Testing Thread - 2019

Tue Oct 01, 2019 2:36 pm

bikerthai wrote:
Revelation wrote:
Yes, it is a given that you cannot have "just the cargo hold unpressurized", but this is the 777x testing thread, and yes, you can find some worthwhile testing you can do if the cabin is unpressurized, the experimental certificate allows for this if you choose to do so.


SEPilot wrote:
Isn’t the 777X pressurized to 6,000 ft, while the old 777s were only pressurized to 8,000 ft? If that is the case then it is not all that surprising that a door popped.


Which is exactly the reason why you do not need to delay flight tests due to the decompression.

1) They can fly unpressurized if they maintain altitude of less than 14000 ft. (Not sure why would they do that, but I know you are allowed to do this by the regulations)

2) They can fly to 8000 ft. pressure altitude for many tests.

3) As long as they do not load the plane to max weight, the wing loading will never reach beyond the point where they decompressed during the test. The flight parameter will still meet the required regulations.

bt


"Yesterday the 777-9 completed it's first flight. The aircraft has around 300 on order and is not allowed to fly above 20k ft, due a door explosion during ground testing a few weeks ago. The test pilot said the first flight was uneventfull and it's really a great aircraft to fly."

Hurray :expressionless:
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