Spetsnaz55
Posts: 96
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 12:20 pm

Boeing just said in our newsletter it was at 99 percent of the final test load conditions.
 
User avatar
SomebodyInTLS
Posts: 1714
Joined: Wed Jun 15, 2016 12:31 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 12:38 pm

zkojq wrote:
morrisond wrote:
Isn't the 777X going to be flying with a lower Cabin Altitude? Aren't they setting it lower like the 787?

Wouldn't that require testing at a higher Pressure Differential than they did when they first certified the 777?

Is that why maybe the Cargo door failed?

That should be an easy fix.


Why is it an easy fix if more pressure was put on a component and it failed? :scratchchin:


Because it's Boeing...?

(I was also tempted to respond to that leap of illogic but decided not to bother...)
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
User avatar
frigatebird
Posts: 1668
Joined: Thu Jun 05, 2008 7:02 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 12:38 pm

justloveplanes wrote:
SEPilot wrote:
enzo011 wrote:
I have a question, I believe the 777X changed the window size from the 777, what effect would this have had and would it be related?

Since this was a cargo door, the windows would have no effect. Neither would the thinner sidewalls since the cargo door is below the floor and the windows and thinner sidewalls are above it. The only relevant change is changing the cabin altitude from 8,000 ft to 6,000 ft.


What about the AlLi Fuselage? Does that material have different bending/brittleness under load? Another factor maybe?



This could be a possibility. Ferpe wrote about it back in 2015: https://leehamnews.com/2015/04/02/bjorn ... derations/
He also mentions the 6,000 to 8000 ft cabin altitude pressure differences between the previous generation 777s and the 777X.

But does the 777X actually have an AL-LI fuselage? At the time of the article it was not yet decided.

My totally non-expert gut feeling says the new CFRP wings which bend quite a bit more, could have had an effect on the cargo door mechanisms.

mjoelnir wrote:
Interesting this discussion. A cargo door has blown out on the 777x static test frame. Boeing has stopped the testing to research whet has happened. Nothing is known, but one thing. This will not have any influence on the test flight and delivery schedule of the 777-9.

And some posters here take Boeing declaration about time frames regarding test flights and EIS of the 777-9 still serious. :sarcastic:


Well, it could be that Boeing expects the fix won't be that major an issue. With the delay caused by the engines, they do have some extra time to resolve this cargo door problem. And while not exactly welcome, when you encounter a problem like this, better now while GE is still busy fixing the GE9x :spin: And apparently, as it happened beyond 100% expected extremest flight loads, Boeings flight test scheme shouldn't be impacted. As long as the fix is tested, approved and implemented on production frames before planned EIS at the end of 2020, Boeing could be right...

Of course nothing is certain :shakehead:
146,318/19/20/21, AB6,332,333,343,345,388, 722,732/3/4/5/G/8,9, 742,74E,744,752,762,763, 772,77E,773,77W,788 AT4/7,ATP,CRK,E75/90,F50/70
 
User avatar
frigatebird
Posts: 1668
Joined: Thu Jun 05, 2008 7:02 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 12:42 pm

Spetsnaz55 wrote:
Boeing just said in our newsletter it was at 99 percent of the final test load conditions.

Thank you. Pardon my ignorance, but does this mean it happened 51% from where it was allowed, or just 1%? As I heard that testing was to go to 150% of maximum load conditions?
146,318/19/20/21, AB6,332,333,343,345,388, 722,732/3/4/5/G/8,9, 742,74E,744,752,762,763, 772,77E,773,77W,788 AT4/7,ATP,CRK,E75/90,F50/70
 
User avatar
SomebodyInTLS
Posts: 1714
Joined: Wed Jun 15, 2016 12:31 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 12:46 pm

Spetsnaz55 wrote:
Boeing just said in our newsletter it was at 99 percent of the final test load conditions.


If true, that's one good point. Now it depends on what exactly failed and how. E.g. a failed latch would simply be beefed up a bit and justified by calculation. If the frame is bending or there is structural failure around it then things would be more complicated.
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
Spetsnaz55
Posts: 96
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 12:51 pm

frigatebird wrote:
Spetsnaz55 wrote:
Boeing just said in our newsletter it was at 99 percent of the final test load conditions.

Thank you. Pardon my ignorance, but does this mean it happened 51% from where it was allowed, or just 1%? As I heard that testing was to go to 150% of maximum load conditions?



Quote from them :

" the testing issue occured during the final minutes of the test, at approximately 99% of the final test loads, and Involved a depressurization of the aft fuselage"
 
User avatar
Finn350
Posts: 1564
Joined: Tue Jul 09, 2013 4:57 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 1:02 pm

frigatebird wrote:
Spetsnaz55 wrote:
Boeing just said in our newsletter it was at 99 percent of the final test load conditions.

Thank you. Pardon my ignorance, but does this mean it happened 51% from where it was allowed, or just 1%? As I heard that testing was to go to 150% of maximum load conditions?


99% of the final test load condition means that it is 1 % less than the final test load condition.
 
User avatar
Revelation
Posts: 21217
Joined: Wed Feb 09, 2005 9:37 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 1:33 pm

Finn350 wrote:
frigatebird wrote:
Spetsnaz55 wrote:
Boeing just said in our newsletter it was at 99 percent of the final test load conditions.

Thank you. Pardon my ignorance, but does this mean it happened 51% from where it was allowed, or just 1%? As I heard that testing was to go to 150% of maximum load conditions?

99% of the final test load condition means that it is 1 % less than the final test load condition.

From earlier we have https://simpleflying.com/boeing-777x-st ... l-testing/ which quotes a Boeing spokesman:

During final load testing on the 777X static test airplane, the team encountered an issue that required suspension of the test. The testing conditions were well beyond any load expected in commercial service. The event is under review and the team is working to understand the root cause. Final load testing is the last in a series of tests that Boeing has been conducting on this full-scale test airplane over the past several months.

Seems ambiguous: is the failure at 99% of the 150% load test, or did they scale the math so we're talking about 148.5% of the 150% load test?

The spokesman said "the testing conditions were well beyond any load expected in commercial service", which suggests the later, but they cleverly do not say "the failure occurred when testing conditions were well beyond any load expected in commercial service" so there is all kinds of wiggle room for the distrustful.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
User avatar
bikerthai
Posts: 2937
Joined: Wed Apr 28, 2010 1:45 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 1:59 pm

Revelation wrote:
Seems ambiguous: is the failure at 99% of the 150% load test, or did they scale the math so we're talking about 148.5% of the 150% load test?


Ultimate testing is 150% load testing. My money is 99% of 150% = 148% which is similar to the A380 when it failed?

Revelation wrote:
The spokesman said "the testing conditions were well beyond any load expected in commercial service", which suggests the later


The comment is not contradictory as the maximum load expected in commercial service is "limit load" = 100% < 150% ultimate.

They re-phrased the event to a decompression event, which is a far cry from "explosion". First thing that came to my mind was that did a pressure relief door blew? Do they have any pressure relief doors in the lower lobe? I know they have pressure release valves . . . but doors?

Lets consider what would happen if a cargo door hinge or latch fail. At the failure point, the door will deform and pressure will be released through the resulting gap in the seal. I would not expect parts to fly off with the door ending across the hangar bay.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
bikerthai
Posts: 2937
Joined: Wed Apr 28, 2010 1:45 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 2:07 pm

In general, limit load is the maximum load that the plane is expected to see (example would be an extra hard landing). There could be some damage (but usually metal should be at or bellow yield). However, the aircraft is expected to be repaired and returned to service.

Ultimate load would be similar to ditching (crash-land - metal beyond yield but not failed) loads at which the airplane is not expected to return to service.

bt
Last edited by bikerthai on Tue Sep 10, 2019 2:09 pm, edited 1 time in total.
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
kalvado
Posts: 1893
Joined: Wed Mar 01, 2006 4:29 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 2:08 pm

bikerthai wrote:
Lets consider what would happen if a cargo door hinge or latch fail. At the failure point, the door will deform and pressure will be released through the resulting gap in the seal. I would not expect parts to fly off with the door ending across the hangar bay.

bt

This is exactly why destructive pressure vessel testing is done with the water, not gas/air whenever possible.
One an escape path opens, air rushes out - but since air is very compressible, the pressure drop is relatively slow - unlike uncompressible water, where a small volume increase results in almost instant pressure drop.
In case of air, pressure mostly holds up against damaged part, and in addition dynamic loads from airflow (and whatever wasn't properly secured inside) - so shrapnel starts flying around.
And this is exactly why such test shouldn't be planned as destructive without much more significant precautions than what was reported - people saw the accident with their own eyes, meaning they were potentially within shrapnel range; thank god for no injuries.
 
User avatar
bikerthai
Posts: 2937
Joined: Wed Apr 28, 2010 1:45 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 2:16 pm

kalvado wrote:
And this is exactly why such test shouldn't be planned as destructive without much more significant precautions than what was reported - people saw the accident with their own eyes, meaning they were potentially within shrapnel range; thank god for no injuries.


If you look at the 787 destructive test, you will get a feel of the precaution they would have in placed. I would guess they would have netting to prevent flying debris in case the composite wing fail.
"Seeing it with their own eyes" could also mean from behind a plexi-barrier.

Historically, the test was tested beyond 150% to failure in order to gauge how much growth is available. However the 787 test was not to failure (breaking) and I suppose the 777 with it's composite wing would not have been tested to breaking either.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
Francoflier
Posts: 4871
Joined: Wed Oct 31, 2001 12:27 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 2:21 pm

Must have been quite the bang... I hope the video eventually gets released.
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
Spetsnaz55
Posts: 96
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 2:45 pm

kalvado wrote:
bikerthai wrote:
Lets consider what would happen if a cargo door hinge or latch fail. At the failure point, the door will deform and pressure will be released through the resulting gap in the seal. I would not expect parts to fly off with the door ending across the hangar bay.

bt

This is exactly why destructive pressure vessel testing is done with the water, not gas/air whenever possible.
One an escape path opens, air rushes out - but since air is very compressible, the pressure drop is relatively slow - unlike uncompressible water, where a small volume increase results in almost instant pressure drop.
In case of air, pressure mostly holds up against damaged part, and in addition dynamic loads from airflow (and whatever wasn't properly secured inside) - so shrapnel starts flying around.
And this is exactly why such test shouldn't be planned as destructive without much more significant precautions than what was reported - people saw the accident with their own eyes, meaning they were potentially within shrapnel range; thank god for no injuries.


Watch a YouTube video on how they do the testing. They watch from inside a building though monitors. Nobody is within shrapnel range when testing is going on
 
WIederling
Posts: 8744
Joined: Sun Sep 13, 2015 2:15 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 2:49 pm

Oykie wrote:
I can’t seem to recall that Boeing has blamed EASA for the MAX still being grounded? They have not sent their fix to approval as far as I know


Obviously they would not try that.
But who inserts the funny rumors "ready to go, just EASA hanging back"
into the discussions ( media, specialist sites like here, .. )
to the potential benefit of Boeing's publicly perceived performance ?
Q3 reports are coming up. you have to prepare your bedding accordingly.
Murphy is an optimist
 
DenverTed
Posts: 247
Joined: Wed Mar 27, 2019 11:12 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 2:52 pm

Is it academically correct to speak of anything over 100%? I thought the percent scale ends at 100. The test is for a load that is 1.5 times some other load or something like that?
 
User avatar
lightsaber
Moderator
Posts: 17925
Joined: Wed Jan 19, 2005 10:55 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 2:59 pm

Spetsnaz55 wrote:
kalvado wrote:
bikerthai wrote:
Lets consider what would happen if a cargo door hinge or latch fail. At the failure point, the door will deform and pressure will be released through the resulting gap in the seal. I would not expect parts to fly off with the door ending across the hangar bay.

bt

This is exactly why destructive pressure vessel testing is done with the water, not gas/air whenever possible.
One an escape path opens, air rushes out - but since air is very compressible, the pressure drop is relatively slow - unlike uncompressible water, where a small volume increase results in almost instant pressure drop.
In case of air, pressure mostly holds up against damaged part, and in addition dynamic loads from airflow (and whatever wasn't properly secured inside) - so shrapnel starts flying around.
And this is exactly why such test shouldn't be planned as destructive without much more significant precautions than what was reported - people saw the accident with their own eyes, meaning they were potentially within shrapnel range; thank god for no injuries.


Watch a YouTube video on how they do the testing. They watch from inside a building though monitors. Nobody is within shrapnel range when testing is going on

It is exciting when something impales itself into the bullet proof glass. It wasn't a Boeing product and only once in my career. Much more exciting for the group of executives on a tour near the window. A low risk test point too. Oops, a typo in actuator command doesn't care what you intended when you can go past the motion sensor measurement range...

Boring testing until it isn't.

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.
 
User avatar
Finn350
Posts: 1564
Joined: Tue Jul 09, 2013 4:57 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:02 pm

DenverTed wrote:
Is it academically correct to speak of anything over 100%? I thought the percent scale ends at 100. The test is for a load that is 1.5 times some other load or something like that?


Yes it is. Discount cannot be more than 100 %, but there is no limit in an increase percentage. 200 % increase means simply triple the original.
 
WIederling
Posts: 8744
Joined: Sun Sep 13, 2015 2:15 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:02 pm

DenverTed wrote:
Is it academically correct to speak of anything over 100%? I thought the percent scale ends at 100. The test is for a load that is 1.5 times some other load or something like that?


"percent" is normalization to some reference value given in 1/100th of that reference value.
Nothing says your range upper bound is limited to that reference value.
Murphy is an optimist
 
User avatar
lightsaber
Moderator
Posts: 17925
Joined: Wed Jan 19, 2005 10:55 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:09 pm

DenverTed wrote:
Is it academically correct to speak of anything over 100%? I thought the percent scale ends at 100. The test is for a load that is 1.5 times some other load or something like that?

100% is the maximum load the aircraft will see in flight. So yes. All proof testing is done in engineering at a multiple of the maximum load.

So calculate the maximum lift of the wing. Aerodynamically you can only create so much lift (no more is possible) capped at a G limit where you already killed the over 60 year olds in the back. Then test to 150% of that load. A standard value in well engineered product.

Sloppy engineered not flying stuff to 500% to 600%.

I worked one program, that was incredibly advanced, where we built only to 100% of maximum possible stress, but we understood the risks of tolerance and not verifiable manufacturing defects, and had an estimate of worst case non visible damage. Crazy fragile. Crazy light... (100kg assemblies versus 500kg if made to normal process).

Lightsaber
IM messages to mods on warnings and bans will be ignored and nasty ones will result in a ban.
 
User avatar
Revelation
Posts: 21217
Joined: Wed Feb 09, 2005 9:37 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:13 pm

WIederling wrote:
DenverTed wrote:
Is it academically correct to speak of anything over 100%? I thought the percent scale ends at 100. The test is for a load that is 1.5 times some other load or something like that?


"percent" is normalization to some reference value given in 1/100th of that reference value.
Nothing says your range upper bound is limited to that reference value.

Yep, we have 100 cents to the dollar/euro, so "per cent" is "per 1/100th" and of course we can count beyond 100 cents...
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
9Patch
Posts: 333
Joined: Wed Mar 13, 2019 10:38 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:14 pm

frigatebird wrote:
But does the 777X actually have an AL-LI fuselage? At the time of the article it was not yet decided.

I thought it did, but this recent article says it does not:

Boeing Suspends 777X Loads Tests After Pressure Failure

Although the 777X fuselage is constructed of standard aluminum rather than the stiffer composite material used in the 787, the aircraft has been designed to operate at a higher internal pressure than the current model.

https://aviationweek.com/commercial-avi ... re-failure
Last edited by 9Patch on Tue Sep 10, 2019 3:19 pm, edited 2 times in total.
 
User avatar
747classic
Posts: 2646
Joined: Sat Aug 15, 2009 9:13 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:15 pm

Most of us (incl. myself) initially got the impression that the failure occured during the combined max wingflex and pressurized fuselage test.
However the failure occurred according the Aviation week article of Guy Norris during the (first) fuselage high blow test. (without wing load)
See : https://aviationweek.com/commercial-avi ... re-failure
According Boeing at 99% of the max.load of 150% differential pressure (14,9 psi) the door failure occured.
The problem Boeing is facing that the next test (150% wingload + pressurized fuselage) cannot be performed before the door or door frame structure has been repaired (and reinforced).
But seen the extra time needed to modify the GE9X engines Boeing doesn't anticipate an extra delay due this issue.
We will see how much time is needed for fixing the static test fuselage.

For an explanation of the different static test of the 787, see : https://www.boeing.com/news/frontiers/a ... i_ca05.pdf
Operating a twin over the ocean, you're always one engine failure from a total emergency.
 
Spetsnaz55
Posts: 96
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:22 pm

9Patch wrote:
frigatebird wrote:
But does the 777X actually have an AL-LI fuselage? At the time of the article it was not yet decided.

I thought it did, but this recent article says it does not:

Boeing Suspends 777X Loads Tests After Pressure Failure

Although the 777X fuselage is constructed of standard aluminum rather than the stiffer composite material used in the 787, the aircraft has been designed to operate at a higher internal pressure than the current model.

https://aviationweek.com/commercial-avi ... re-failure



It does. They are just stating that's its aluminum based in the article. Doesn't meant it's not the AL-LI

It is the AL-LI thought
 
9Patch
Posts: 333
Joined: Wed Mar 13, 2019 10:38 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:29 pm

Spetsnaz55 wrote:
9Patch wrote:
frigatebird wrote:
But does the 777X actually have an AL-LI fuselage? At the time of the article it was not yet decided.

I thought it did, but this recent article says it does not:

Boeing Suspends 777X Loads Tests After Pressure Failure

Although the 777X fuselage is constructed of standard aluminum rather than the stiffer composite material used in the 787, the aircraft has been designed to operate at a higher internal pressure than the current model.

https://aviationweek.com/commercial-avi ... re-failure



It does. They are just stating that's its aluminum based in the article. Doesn't meant it's not the AL-LI

It is the AL-LI thought


So AL-LI is considered standard aluminum?
 
Spetsnaz55
Posts: 96
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:44 pm

9Patch wrote:
Spetsnaz55 wrote:
9Patch wrote:
I thought it did, but this recent article says it does not:




It does. They are just stating that's its aluminum based in the article. Doesn't meant it's not the AL-LI

It is the AL-LI thought


So AL-LI is considered standard aluminum?


If you don't get it then I'll stop.

I read an article the other day that stated all of the Boeing doors exploded during the static testing.. they must be right
 
asdf
Posts: 372
Joined: Tue Mar 18, 2014 12:03 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:46 pm

Finn350 wrote:
frigatebird wrote:
Spetsnaz55 wrote:
Boeing just said in our newsletter it was at 99 percent of the final test load conditions.

Thank you. Pardon my ignorance, but does this mean it happened 51% from where it was allowed, or just 1%? As I heard that testing was to go to 150% of maximum load conditions?


99% of the final test load condition means that it is 1 % less than the final test load condition.


a fail @ 99% of the 150% load is simply bad luck
 
User avatar
Revelation
Posts: 21217
Joined: Wed Feb 09, 2005 9:37 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 3:50 pm

zkojq wrote:
mjoelnir wrote:
Interesting this discussion. A cargo door has blown out on the 777x static test frame. Boeing has stopped the testing to research whet has happened. Nothing is known, but one thing. This will not have any influence on the test flight and delivery schedule of the 777-9.

And some posters here take Boeing declaration about time frames regarding test flights and EIS of the 777-9 still serious. :sarcastic:


I'm most surprised at the people here who speak about the matter as if a cargo door exploding during testing is somehow a good thing. :eyepopping:

It's not a good thing, but it is an ordinary thing.

AvWeek reported:

The ongoing delay to the 777-9 flight test program due to issues with the aircraft’s General Electric GE9X engines means that Boeing will likely have ample margin to modify the failed part and re-run the test.

I'm most surprised at the people here who don't understand that testing is just that, testing, and limits are being pushed.

If they knew the answer ahead of time, they wouldn't bother with the testing.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
hivue
Posts: 1917
Joined: Tue Feb 26, 2013 2:26 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 4:00 pm

asdf wrote:
a fail @ 99% of the 150% load is simply bad luck


I would think the question is what does the airplane have to ultimately be certified to -- the 100% or the 150%? I would guess the 100%. However, I believe, e.g., flutter testing needs to be done to well beyond Mmo/Vmo, all the way to design limit.
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
User avatar
par13del
Posts: 8910
Joined: Sun Dec 18, 2005 9:14 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 4:04 pm

Revelation wrote:
I'm most surprised at the people here who don't understand that testing is just that, testing, and limits are being pushed.

If they knew the answer ahead of time, they wouldn't bother with the testing.

My new understanding is that testing is done for validation only, not to also catch errors or flaws. The danger there of course is that you will expend more efforts to ensure that your test are always successful, but.........
 
kalvado
Posts: 1893
Joined: Wed Mar 01, 2006 4:29 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 4:05 pm

hivue wrote:
asdf wrote:
a fail @ 99% of the 150% load is simply bad luck


I would think the question is what does the airplane have to ultimately be certified to -- the 100% or the 150%? I would guess the 100%. However, I believe, e.g., flutter testing needs to be done to well beyond Mmo/Vmo, all the way to design limit.

You do not use every tiny bit of structure capabilities in routine operation. This is something called "safety margin" - to account for imperfections, wear, statistical variation etc.
 
User avatar
Stitch
Posts: 26346
Joined: Wed Jul 06, 2005 4:26 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 4:08 pm

hivue wrote:
I would think the question is what does the airplane have to ultimately be certified to -- the 100% or the 150%? I would guess the 100%. However, I believe, e.g., flutter testing needs to be done to well beyond Mmo/Vmo, all the way to design limit.


The certification standard would be 150% or they would never go that high.

The certification standard is 150% for the wing-bend, so it stands to reason it is the same for this pressure test.
 
9Patch
Posts: 333
Joined: Wed Mar 13, 2019 10:38 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 5:02 pm

Spetsnaz55 wrote:
9Patch wrote:
Spetsnaz55 wrote:


It does. They are just stating that's its aluminum based in the article. Doesn't meant it's not the AL-LI

It is the AL-LI thought


So AL-LI is considered standard aluminum?


If you don't get it then I'll stop.

I read an article the other day that stated all of the Boeing doors exploded during the static testing.. they must be right

OK, so you think the Aviation Week article got it wrong.

No need to be snarky and dismissive.
 
User avatar
bikerthai
Posts: 2937
Joined: Wed Apr 28, 2010 1:45 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 5:04 pm

Keep in mind that if this was a pressure only test that failed, then the major impact would be how it would react if/when they do full blown pressure test with wing bending test.

The other thing to keep in mind is that as I recall (some one could correct me) is that regulation do not require double failure mode for ultimate testing. When they do the 150% wing bending test, the fuselage is not pressurized to 150% pressure - maybe just up to limit (again someone could correct me).

Finally, if they find that the fuselage could not hold pressure to 150% then it would not be critical to the flight test program or delivery as they could dial back the pressure altitude to say 6500ft instead of 6000ft until they get the fix incorporated.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
Finn350
Posts: 1564
Joined: Tue Jul 09, 2013 4:57 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 5:19 pm

The problem as I see it is that this was not the final test of the static test program. In other words, they have to repair the fuselage, calculate what effects the repaired fuselage has to the rest of the test program, and continue static tests after that. I am sure that they are able to do that, though.
 
User avatar
Erebus
Posts: 1034
Joined: Tue Oct 20, 2015 2:40 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 5:21 pm

Has Boeing completed fatigue testing of this frame? If not, any word on how far along they are?
 
User avatar
Stitch
Posts: 26346
Joined: Wed Jul 06, 2005 4:26 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 5:28 pm

bikerthai wrote:
Finally, if they find that the fuselage could not hold pressure to 150% then it would not be critical to the flight test program or delivery as they could dial back the pressure altitude to say 6500ft instead of 6000ft until they get the fix incorporated.


I would imagine the fuselage is pressurized to standard (100%) for the flight test program, so Boeing should still be able to run at 6000 feet.
 
User avatar
Revelation
Posts: 21217
Joined: Wed Feb 09, 2005 9:37 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 5:33 pm

par13del wrote:
Revelation wrote:
I'm most surprised at the people here who don't understand that testing is just that, testing, and limits are being pushed.

If they knew the answer ahead of time, they wouldn't bother with the testing.

My new understanding is that testing is done for validation only, not to also catch errors or flaws. The danger there of course is that you will expend more efforts to ensure that your test are always successful, but.........

It's just semantics to say it's for validation only, the test would not be run if you knew there would be no issues found.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
hivue
Posts: 1917
Joined: Tue Feb 26, 2013 2:26 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 5:35 pm

kalvado wrote:
You do not use every tiny bit of structure capabilities in routine operation. This is something called "safety margin" - to account for imperfections, wear, statistical variation etc.


Correct. My post was about certification, though. Based on some replies it sounds like the airplane will be certified to design limits -- that is, the certification testing will include the "safety margin." I don't know whether during flight test they will check cabin pressurization to the max that is supposed to ever be seen in normal operation or to the 150%. My guess is any certification to 150% would be based on results from the static testing and not flight testing. However, as I mentioned in my post, I think flutter testing will be done to speeds beyond what is ever expected to be seen in normal operation -- maybe 0.96M or 0.98M?
"You're sitting. In a chair. In the SKY!!" ~ Louis C.K.
 
iamlucky13
Posts: 1055
Joined: Wed Aug 08, 2007 12:35 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 5:43 pm

Spetsnaz55 wrote:
iamlucky13 wrote:
mjoelnir wrote:
The worst problem for Boeing could be the number of frames already built, all to be reworked with the changes. I start to question how sensible it is, to start production of customer frames, before you have finished certain tests. In this case the static tests and parts of the flight testing. The dynamic test run to long to wait for the final results.
In this case the rework on the production frames has to wait for the redesign and retesting. I assume flight test can commence before the new design regarding the cargo door problem is finished.


Aircraft development schedules already factor in time to incorporate changes determined to be necessary during certification. The first 777X to be delivered could well be months away from even starting assembly.

There is a cost to retrofitting aircraft versus waiting until the certification configuration is set in stone, but the cost of creating a production system, qualifying it to produce an aircraft, and then leaving everyone sitting around doing nothing for a year or more is usually even higher.


Huh? The 4th or 5th Emirates 777x is getting final body join right now


Yes, and I expect aircraft that begin assembly after it will be delivered before it, due to changes that will be incorporated, such as perhaps to the cargo door.

Opus99 wrote:
morrisond wrote:
CNBC just reported that Boeing stated the failed door will not impact their schedule - which is still First Flight beginning of 2020 with First Customer Delivery by end of 2020.

They sure seem fixated on this end of 2020 EIS. I don’t know what magic they plan on performing to ensure that.


They won't update it until they know with decent confidence what they are changing it to. Until then, they will carefully word statements like, "We are maintaining our first delivery target for the end of 2020." That sounds like a firm target, but the part they will emphasize if the SEC asks is that they aren't making a statement about the likelihood of meeting that target.
 
Spetsnaz55
Posts: 96
Joined: Wed Feb 20, 2019 2:38 am

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 6:14 pm

747classic wrote:
Most of us (incl. myself) initially got the impression that the failure occured during the combined max wingflex and pressurized fuselage test.
However the failure occurred according the Aviation week article of Guy Norris during the (first) fuselage high blow test. (without wing load)
See : https://aviationweek.com/commercial-avi ... re-failure
According Boeing at 99% of the max.load of 150% differential pressure (14,9 psi) the door failure occured.
The problem Boeing is facing that the next test (150% wingload + pressurized fuselage) cannot be performed before the door or door frame structure has been repaired (and reinforced).
But seen the extra time needed to modify the GE9X engines Boeing doesn't anticipate an extra delay due this issue.
We will see how much time is needed for fixing the static test fuselage.

For an explanation of the different static test of the 787, see : https://www.boeing.com/news/frontiers/a ... i_ca05.pdf



And according to this CNN article the wings were bent.. that's why I take everything with a grain of salt. Another article I read said that all doors had blown open in a explosion lol..

https://www.google.com/amp/s/amp.cnn.co ... index.html
 
User avatar
bikerthai
Posts: 2937
Joined: Wed Apr 28, 2010 1:45 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 6:55 pm

Erebus wrote:
Has Boeing completed fatigue testing of this frame? If not, any word on how far along they are?


The fatigue test frame is a separate plane. It will not be complete for a few years. This is a static frame. Typically, they simulate the wear and tear on the static frame by deliberately introducing defects to the structures at various points.

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
WIederling
Posts: 8744
Joined: Sun Sep 13, 2015 2:15 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 7:18 pm

Spetsnaz55 wrote:
Quote from them :

" the testing issue occured during the final minutes of the test, at approximately 99% of the final test loads, and Involved a depressurization of the aft fuselage"


why would this explosive decompression be limited to the rear fuselage?
no wall in the cabin and the floors are not designed to carry pressure differential.
Murphy is an optimist
 
User avatar
VirginFlyer
Posts: 5242
Joined: Sun Sep 10, 2000 12:27 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 7:54 pm

WIederling wrote:
Spetsnaz55 wrote:
Quote from them :

" the testing issue occured during the final minutes of the test, at approximately 99% of the final test loads, and Involved a depressurization of the aft fuselage"


why would this explosive decompression be limited to the rear fuselage?
no wall in the cabin and the floors are not designed to carry pressure differential.

I think you're misunderstanding what was said; they are not saying that pressure was lost from the aft fuselage and maintained elsewhere, but rather that the after fuselage was where the rupture that caused the depressurisation occurred.

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
 
iamlucky13
Posts: 1055
Joined: Wed Aug 08, 2007 12:35 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 7:57 pm

Erebus wrote:
Has Boeing completed fatigue testing of this frame? If not, any word on how far along they are?


No. Fatigue testing will take years, which is accepted as long as the fatigue test airframe has more cycles than any aircraft in service.

Last I saw, the fatigue test frame was still being hooked up to the actuators and testing hadn't started yet.
 
User avatar
7BOEING7
Posts: 3039
Joined: Fri Oct 12, 2012 5:28 pm

Re: Boeing 777X Testing Thread - 2019

Tue Sep 10, 2019 8:55 pm

Don’t know if anybody has mentioned it but the 747SP had a similar issue during wing testing. A door didn’t blow out but the aft fuselage depresserized
 
WIederling
Posts: 8744
Joined: Sun Sep 13, 2015 2:15 pm

Re: Boeing 777X Testing Thread - 2019

Wed Sep 11, 2019 10:51 am

VirginFlyer wrote:
WIederling wrote:
Spetsnaz55 wrote:
Quote from them :

" the testing issue occured during the final minutes of the test, at approximately 99% of the final test loads, and Involved a depressurization of the aft fuselage"


why would this explosive decompression be limited to the rear fuselage?
no wall in the cabin and the floors are not designed to carry pressure differential.

I think you're misunderstanding what was said; they are not saying that pressure was lost from the aft fuselage and maintained elsewhere, but rather that the after fuselage was where the rupture that caused the depressurisation occurred.

V/F

Hmm, this is quibling over semantics but:
"... Involved a depressurization of the aft fuselage"

I'd parse that as limited to the aft fuselage.
otherwise I'd expect "via", "from", "in" instead of of
proper statement would have been: "depressurization via the aft fuselage cargo hatch."

I expect these statement to be carefully crafted.
i.e. they are not unintentional imprecise or misleading.
Murphy is an optimist
 
User avatar
SomebodyInTLS
Posts: 1714
Joined: Wed Jun 15, 2016 12:31 pm

Re: Boeing 777X Testing Thread - 2019

Wed Sep 11, 2019 12:22 pm

9Patch wrote:
Spetsnaz55 wrote:
9Patch wrote:

So AL-LI is considered standard aluminum?


If you don't get it then I'll stop.

I read an article the other day that stated all of the Boeing doors exploded during the static testing.. they must be right

OK, so you think the Aviation Week article got it wrong.

No need to be snarky and dismissive.


I think he's trying to say that AlLi is just another aluminium alloy, like the typical 2024 and 7075 alloys (with added copper, magnesium, iron, chrome, etc.) used for most of the 20th century. I.e. AlLi can ALSO be referred to as "aluminium". Aircraft have never been made from *pure* aluminium...
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
User avatar
bikerthai
Posts: 2937
Joined: Wed Apr 28, 2010 1:45 pm

Re: Boeing 777X Testing Thread - 2019

Wed Sep 11, 2019 1:53 pm

WIederling wrote:
I'd parse that as limited to the aft fuselage.otherwise I'd expect "via", "from", "in" instead of
proper statement would have been: "depressurization via the aft fuselage cargo hatch."I expect these statement to be carefully crafted. i.e. they are not unintentional imprecise or misleading.


Engineers can be precise but not good with words. PR folks may be good with words but not be as precise. Add auto correction and you can often get imprecise statement in press releases. We've seen enough to know better. :indifferent:

bt
Intelligent seeks knowledge. Enlightened seeks wisdom.
 
User avatar
Revelation
Posts: 21217
Joined: Wed Feb 09, 2005 9:37 pm

Re: Boeing 777X Testing Thread - 2019

Wed Sep 11, 2019 2:12 pm

https://www.flightglobal.com/news/artic ... ue-460780/ has some updates via a Boeing representative.

I'm not sure if it adds or reduces clarity to what we know already.

For me, one key takeaway was: “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 programme schedule".
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos