Door blows off Boeing 777X during stress test(komonews.com)
komonews.com
Door blows off Boeing 777X during stress test
https://komonews.com/news/local/door-blows-off-boeing-777x-during-stress-test
119 comments
Also - need to ensure that all testing methodologies were up to scratch. Here is an article about a KC-135 pressure test that ended up making the plane pop like a balloon [0] - all because the pressure gauge used by the tester didn't have a 'stop' peg and he missed the fact that the needle had cycled around.
A door hatch from the aircraft was found 70 yards away.
[0] - https://theaviationgeekclub.com/time-kc-135-stratotanker-air...
A door hatch from the aircraft was found 70 yards away.
[0] - https://theaviationgeekclub.com/time-kc-135-stratotanker-air...
> Here is another video of a 777 wing test where it broke at 154% of the normal load
I really hope you mean 154% of the max load, and I hope that max load is engineered to be far above what should be seen in actual service. 50% over the normal service load is not what I would consider extreme, and not something I would expect to be acceptable in an aircraft.
I really hope you mean 154% of the max load, and I hope that max load is engineered to be far above what should be seen in actual service. 50% over the normal service load is not what I would consider extreme, and not something I would expect to be acceptable in an aircraft.
Design limit load is for an aircraft at max allowable weight, with the max authorized g loading (often -1 to +2.5g) or the worst anticipated gusts (about 50 ft/sec depending on altitude). You then need to tack on 50% to get the required ultimate load.
50% is indeed not a huge safety margin like you'd get with a bridge or something, which is why you need trained professionals flying it and regular inspections. If you fly into a big enough thunderstorm, the wings can definitely come off. Of course a bigger safety margin would be nice, but every pound of wing spar is a pound less payload. If the FAA required 200% of design limit, flying would be significantly more expensive.
50% is indeed not a huge safety margin like you'd get with a bridge or something, which is why you need trained professionals flying it and regular inspections. If you fly into a big enough thunderstorm, the wings can definitely come off. Of course a bigger safety margin would be nice, but every pound of wing spar is a pound less payload. If the FAA required 200% of design limit, flying would be significantly more expensive.
This is why there's maneuvering speed (VA), or turbulent air penetration speed (VB). It isn't necessary to over design it, you just slow down and, voila, the airfoil will sooner stall than break - and the stall is brief, feels like sluggishness, like a squishy slow stall, not abrupt, and recovery is similar perhaps a bit more abrupt as the airfoil regains lift.
Sure, as long as the gust is mostly vertical (usually true), and you're able to maintain below Va. All of the up and down motion in a serious thunderstorm can easily cause you to exceed Va or even Vne. Many aircraft have broken up in flight because of this. Now it could be that in many accidents, it wouldn't have mattered how strong the wing was -- eventually the speed build build up to the point where a big gust would break it, but I'm sure there are many where say an extra 50% strength would have made the difference.
Now that's also not to say that if you're going to add weight to an airplane in the name of safety that the best place to do it is the wing spar, but there is certainly a tradeoff between safety and weight.
Now that's also not to say that if you're going to add weight to an airplane in the name of safety that the best place to do it is the wing spar, but there is certainly a tradeoff between safety and weight.
> 50% is indeed not a huge safety margin like you'd get with a bridge or something
Safety margins for bridges are like 25-50%.
Safety margins for bridges are like 25-50%.
That's interesting. I know that they used to be a lot more. Perhaps we should be glad that most of the bridges we drive over were built before FEM, and they just used a lot more steel. I wonder how well a bridge designed with a 25% safety margin is going to perform when it's poorly maintained for 50 years and rusting like a lot of bridges in the U.S.
The reason this works is that the safety margins accumulate. You have a safety margin on:
* the loading on the bridge, which can be higher than the calculated amount.
* the resistance of the materials used, that can be lower than the requested amount.
* the quality of the soil,
* the lifespan of the bridge,
* ...
So the loading can be 25% percent higher, the materials can be 25% worse, the soil can be 25% worse, the lifespan can be 25% higher, ... and at the end you get a bridge that would still work if everything fails with a margin of 25%.
If the loads are 30% higher, the bridge might or might not fail. Who knows. Even though there are many other safety factors, and the bridge probably won't fail, it was not designed for that. There might be a critical part somewhere that has a resistance that's 25% worse than what it should be, and it therefore can only support a 25% overload, and with 30% that part might fail.
Bridges are designed to fail very slowly, loudly, and visibly, to avoid loss of functionality (e.g. when a bridge start to fail, this becomes obvious, and you still have months or years to sanitize the bridge).
I expect airplanes to have much tighter safety margins (<15% or <10%). The loads are more accurately known, the materials are higher quality, everything passes more extensive quality assurance tests, weight is much more important and companies are willing to pay prime prices on materials, manufacturing, etc. to reduce it, etc.
Safety margins aren't chosen arbitrarily. The job of a safety margin is to quantify an uncertainty, and with enough money thrown at each one, most of the uncertainties can be quite precisely quantified. Then it's the job of the designer to say "This plane should be in service for 50 years", and from the uncertainties and statistical analysis you can compute the highest load that the plane will receive in those 50 years with a certain quantified margin of error, and continue the design using that.
* the loading on the bridge, which can be higher than the calculated amount.
* the resistance of the materials used, that can be lower than the requested amount.
* the quality of the soil,
* the lifespan of the bridge,
* ...
So the loading can be 25% percent higher, the materials can be 25% worse, the soil can be 25% worse, the lifespan can be 25% higher, ... and at the end you get a bridge that would still work if everything fails with a margin of 25%.
If the loads are 30% higher, the bridge might or might not fail. Who knows. Even though there are many other safety factors, and the bridge probably won't fail, it was not designed for that. There might be a critical part somewhere that has a resistance that's 25% worse than what it should be, and it therefore can only support a 25% overload, and with 30% that part might fail.
Bridges are designed to fail very slowly, loudly, and visibly, to avoid loss of functionality (e.g. when a bridge start to fail, this becomes obvious, and you still have months or years to sanitize the bridge).
I expect airplanes to have much tighter safety margins (<15% or <10%). The loads are more accurately known, the materials are higher quality, everything passes more extensive quality assurance tests, weight is much more important and companies are willing to pay prime prices on materials, manufacturing, etc. to reduce it, etc.
Safety margins aren't chosen arbitrarily. The job of a safety margin is to quantify an uncertainty, and with enough money thrown at each one, most of the uncertainties can be quite precisely quantified. Then it's the job of the designer to say "This plane should be in service for 50 years", and from the uncertainties and statistical analysis you can compute the highest load that the plane will receive in those 50 years with a certain quantified margin of error, and continue the design using that.
Sorry, I mistyped. It is indeed the maximum theoretical load as calculated by the engineering team.
Specifically from the video description:
> This Boeing 777 wing was tested to destruction, finally breaking at one fifty four percent of the designed limit load.
> This Boeing 777 wing was tested to destruction, finally breaking at one fifty four percent of the designed limit load.
I would still expect the `maximum theoretical load` to be well above the `designed limit load`.
And it is, it is 154% or slightly more than 2.5x the 'design limit load'.
90% of $100 is not $190
Interestingly the 154% number seems to be gone from the article now
The language is tricky, if you interpret it as I did, or 154% "more" than the design limit, then it is the design limit plus 1.54 more design limits. Like saying you salary is $100 and we're paying you 90% beyond your salary. Then you would expect to get $190.
If you interpret it to be 154% "of" the design limit, then I would agree it would be 1.54x the design limit.
Since other publications from Boeing, and Boeing staff at the "Future of Flight" museum in Everett have said that the planes are safer because they can withstand over twice their design limit, I read the 154% number as the amount "over" the limit.
Since folks from Boeing read Hackernews, it would be great for one of them to chime in here with some clarification :-).
The language is tricky, if you interpret it as I did, or 154% "more" than the design limit, then it is the design limit plus 1.54 more design limits. Like saying you salary is $100 and we're paying you 90% beyond your salary. Then you would expect to get $190.
If you interpret it to be 154% "of" the design limit, then I would agree it would be 1.54x the design limit.
Since other publications from Boeing, and Boeing staff at the "Future of Flight" museum in Everett have said that the planes are safer because they can withstand over twice their design limit, I read the 154% number as the amount "over" the limit.
Since folks from Boeing read Hackernews, it would be great for one of them to chime in here with some clarification :-).
It's not a matter of interpretation or tricky language. The video says "of" [1] so it's 1.54 times the design limit.
[1] https://youtu.be/Ai2HmvAXcU0?t=45
[1] https://youtu.be/Ai2HmvAXcU0?t=45
The video was clear and left no room for interpretation.
Planes are safer because “they can withstand twice their design limit” is senseless. The 2x factor you are thinking of is the design limit. The design limit has all of the huge safety margins built in for the normal load limits.
The planes are designed to take at least 2x the max normal loads.
Planes are safer because “they can withstand twice their design limit” is senseless. The 2x factor you are thinking of is the design limit. The design limit has all of the huge safety margins built in for the normal load limits.
The planes are designed to take at least 2x the max normal loads.
It’s in the above Boeing video not the article.
Slightly more than 1.5x you mean. And yeah, since the design limit load is already going to have a safety margin over the max anticipated load, as long as the test performs some amount beyond that design level, it's good.
Edit: This is assuming the 'design level' is the level it was designed to withstand, which is how I would normally understand the term. Having watched the full video now though, it sounds like it actually exceeded the expected max force that could be expected in the real world by 1.54 times, and that the design anticipated about 1.5x. So indeed, it hit dead-on the design expectation, rather than vastly exceeding it—but that's fine, because the design included a 50% margin of error (and one would hope, a conservative worst-case estimate).
Edit: This is assuming the 'design level' is the level it was designed to withstand, which is how I would normally understand the term. Having watched the full video now though, it sounds like it actually exceeded the expected max force that could be expected in the real world by 1.54 times, and that the design anticipated about 1.5x. So indeed, it hit dead-on the design expectation, rather than vastly exceeding it—but that's fine, because the design included a 50% margin of error (and one would hope, a conservative worst-case estimate).
Ok, I'm hijacking this thread because there's some confusion about 'limit' load.
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf...
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf...
You're not hijacking it, just adding some contextual information, namely: "Strength requirements are specified in terms of limit loads (the maximum loads to be expected in service) and ultimate loads (limit loads multiplied by prescribed factors of safety). Unless otherwise provided, prescribed loads are limit loads."
Was that an airplane joke?
Good point about it being normal for stuff to break during a stress test. However, it seems the door blowing off is not something that normally happens and that to me is more worrisome than if it was a common failure when the stresses greatly exceed the theoretical limits.
>Former Boeing Engineer Dr. Todd Curtis runs Airsafe.com and said this doesn't happen often. "I've never heard of a case where a door popped off like this during a stress test before," he said. "Doesn't mean it hasn't happened before, I'm just not aware of it."
>Former Boeing Engineer Dr. Todd Curtis runs Airsafe.com and said this doesn't happen often. "I've never heard of a case where a door popped off like this during a stress test before," he said. "Doesn't mean it hasn't happened before, I'm just not aware of it."
You expect things stressed beyond limits to break where you expect them to, and the point of the test is to show that the failure modes are the expected ones. Having a door pressure seal fail explosively during an airframe stress test sounds to me very much like an UNexpected failure mode. That's bad.
It's doubly unexpected as, in theory, the 777X is just a variant of the 777, itself a plane that didn't blow its doors out under testing.
in theory, the 777X is just a variant of the 777
Uh oh. Haven't we seen this story before with a different model (cough 737 cough)?
Uh oh. Haven't we seen this story before with a different model (cough 737 cough)?
"A door blew off a Boeing 777X as the new plane was undergoing what was supposed to be its final structural inspection by federal regulators."
It's literally the first sentence of the article.
I doubt Boeing were pushing the envelopes further than the FAA required. And a door fell out.
It's literally the first sentence of the article.
I doubt Boeing were pushing the envelopes further than the FAA required. And a door fell out.
The second, third, and fourth sentences seem to imply otherwise?
>The test is meant to push the plane beyond its limits. Engineers had the plane pressurized and on the ground. They loaded it up well beyond capacity and bent its wings in an extreme manner, in a way almost certain to never happen in the real world.
and also further down, more "not necessarily a normal test" evidence:
>... The ultimate load test is the latest in a series of tests that Boeing has been conducting on this full-scale test airplane over the past several months."
>The test is meant to push the plane beyond its limits. Engineers had the plane pressurized and on the ground. They loaded it up well beyond capacity and bent its wings in an extreme manner, in a way almost certain to never happen in the real world.
and also further down, more "not necessarily a normal test" evidence:
>... The ultimate load test is the latest in a series of tests that Boeing has been conducting on this full-scale test airplane over the past several months."
The second, third, and fourth sentences seem to imply otherwise?
Semantics.
https://www.seattletimes.com/business/boeing-aerospace/door-...
The Seattle Times explains it thusly:
During the ultimate load test, the wings are then pulled upward. To pass the test and be certified, the wings must bend without breaking until the load on them reaches at least 150 percent of the normally expected load.
…
Sometimes this final test is continued beyond the 150 percent load target until a wing actually breaks. But not always.
…
This time, however, though the wings did not give way; it was one of the doors that failed — an outcome that is definitely not supposed to happen.
Semantics.
https://www.seattletimes.com/business/boeing-aerospace/door-...
The Seattle Times explains it thusly:
During the ultimate load test, the wings are then pulled upward. To pass the test and be certified, the wings must bend without breaking until the load on them reaches at least 150 percent of the normally expected load.
…
Sometimes this final test is continued beyond the 150 percent load target until a wing actually breaks. But not always.
…
This time, however, though the wings did not give way; it was one of the doors that failed — an outcome that is definitely not supposed to happen.
I mean, when it comes down to it, I’d rather lose a door than a wing though, right...?
Losing a door can have very serious consequences:
https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981
The cargo hatch blew open and the cabin floor collapsed on account of differential pressure, disabling the rudder, elevator and rear engine controls.
This may well not happen on a 777X -- various other airplanes have lost part of their cabin structure without crashing -- but an unexpected event calls into doubt your design.
https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243
https://en.wikipedia.org/wiki/Turkish_Airlines_Flight_981
The cargo hatch blew open and the cabin floor collapsed on account of differential pressure, disabling the rudder, elevator and rear engine controls.
This may well not happen on a 777X -- various other airplanes have lost part of their cabin structure without crashing -- but an unexpected event calls into doubt your design.
https://en.wikipedia.org/wiki/Aloha_Airlines_Flight_243
It depends on the stress test
If you're testing it up to the limit then no, it is not expected.
But if you're pushing it beyond the design limit then yes, it is expected to break.
Some wing tests are done beyond the limit, some are done below the limit (non-destructive tests cost less, that's why they're preferred, but for a new design they might just push it beyond the limit to see when does it effectively fail)
If you're testing it up to the limit then no, it is not expected.
But if you're pushing it beyond the design limit then yes, it is expected to break.
Some wing tests are done beyond the limit, some are done below the limit (non-destructive tests cost less, that's why they're preferred, but for a new design they might just push it beyond the limit to see when does it effectively fail)
>You would expect things to break during a stress test.
Given the stunned silence and halting of further testing I'm guessing this wasn't a stress it till breaking type stress test
Given the stunned silence and halting of further testing I'm guessing this wasn't a stress it till breaking type stress test
If I ever write a library to perform stress tests, I'll call it one-fifty-four.
> You would expect things to break during a stress test.
Except, the whole point of the test is to stress the plane and to have nothing break.
The test is designed to make sure the aircraft has built-in safety (i.e. is over engineered).
When the A380 was attempting to earn it's certification it failed a similar static wing test:
http://www.airmech.co.uk/forums/showthread.php/5340-A380-Win...
Except, the whole point of the test is to stress the plane and to have nothing break.
The test is designed to make sure the aircraft has built-in safety (i.e. is over engineered).
When the A380 was attempting to earn it's certification it failed a similar static wing test:
http://www.airmech.co.uk/forums/showthread.php/5340-A380-Win...
> Except, the whole point of the test is stress the plane and to have nothing break.
That depends on the type of stress test. Some stress tests are to confirm it acts as expected. Other stress tests are used to determine modes of failure. Good engineering isn't just building stuff to spec and assuming it works, just as good programming isn't just writing code and assuming it works as expected because the compiler doesn't throw any errors.
It's very useful to try to break something and see what happens. That's why engineers provide more stresses than systems are designed for to see what breaks, and that's why programmers sometimes run programs in environments constrained in ways it wasn't meant to run in (no disk space, out of memory, network drop, etc), and run fuzzers.
That depends on the type of stress test. Some stress tests are to confirm it acts as expected. Other stress tests are used to determine modes of failure. Good engineering isn't just building stuff to spec and assuming it works, just as good programming isn't just writing code and assuming it works as expected because the compiler doesn't throw any errors.
It's very useful to try to break something and see what happens. That's why engineers provide more stresses than systems are designed for to see what breaks, and that's why programmers sometimes run programs in environments constrained in ways it wasn't meant to run in (no disk space, out of memory, network drop, etc), and run fuzzers.
Also it depends on how far in the design process they are. Early failure is good. Late is bad, but mostly for them, they'll have to loopback.
Very importantly, this hasn't been described as a "test failure."
No indication of what the test criteria were, if any. Some tests, especially those past design limits, are just for informational data.
No indication of what the test criteria were, if any. Some tests, especially those past design limits, are just for informational data.
Very importantly, this hasn't been described as a "test failure."
That was heavily implied:
Sources tell KOMO there was a stunned silence after it happened.
…
an event occurred that forced the test team to halt testing. … The team is currently working to understand what happened and ensure the area is safe for work to continue.
Edit: You're not going to silence the crowd with a successful test and you don't temporarily halt testing because of a successful test.
Edit 2: Seattle Times says this explicitly: This ground test failure is another blow.
That was heavily implied:
Sources tell KOMO there was a stunned silence after it happened.
…
an event occurred that forced the test team to halt testing. … The team is currently working to understand what happened and ensure the area is safe for work to continue.
Edit: You're not going to silence the crowd with a successful test and you don't temporarily halt testing because of a successful test.
Edit 2: Seattle Times says this explicitly: This ground test failure is another blow.
Yes, but this isn't the language they'd use if one of the test success criteria was "no door blows out" and then a door blows out.
This is evidenced by their plan to "analyze the door and run the test again." If this were actually a test failure, they'd be "analyzing the door, redesigning a bunch of stuff, and running the test again."
This is evidenced by their plan to "analyze the door and run the test again." If this were actually a test failure, they'd be "analyzing the door, redesigning a bunch of stuff, and running the test again."
>Except, the whole point of the test is to stress the plane and to have nothing break.
What? No it's not. The entire point of these tests is specifically to break things. If nothing breaks, they did not perform the test correctly.
>When the A380 was attempting to earn it's certification it failed a similar static wing test:
No, it didn't. It passed the test handily. The wing broke well beyond the max load limit, which is what they were testing for.
edit for the sake of being less of an argumentative asshole: I see where you're coming from when you say that it was a 'failure'. However, what I mean to say is that while the wings failed in the test, the failure was intentional, and the data gathered during the test was exactly what was needed to prove that the A380's wings were strong enough for certification, and the A380 was certified based on the results of this test. In my mind, that means the test passed.
What? No it's not. The entire point of these tests is specifically to break things. If nothing breaks, they did not perform the test correctly.
>When the A380 was attempting to earn it's certification it failed a similar static wing test:
No, it didn't. It passed the test handily. The wing broke well beyond the max load limit, which is what they were testing for.
edit for the sake of being less of an argumentative asshole: I see where you're coming from when you say that it was a 'failure'. However, what I mean to say is that while the wings failed in the test, the failure was intentional, and the data gathered during the test was exactly what was needed to prove that the A380's wings were strong enough for certification, and the A380 was certified based on the results of this test. In my mind, that means the test passed.
What? No it's not.
Yes, it is. The point is to check that the wings can take 150% of the rated load. The point of an ultimate load test is NOT to break things.
Yes, it is. The point is to check that the wings can take 150% of the rated load. The point of an ultimate load test is NOT to break things.
The first time the A380 tried the test it failed. Read the link.
And yes it did eventually pass that wing test only because if it had not it would not never have been certified.
And yes it did eventually pass that wing test only because if it had not it would not never have been certified.
>The first time the A380 tried the test it failed. Read the link.
I suggest you read it. The A380 did not fail. It says so in the link you provided.
I suggest you read it. The A380 did not fail. It says so in the link you provided.
"We'll be able to demonstrate" that the plane meets requirements, "maybe with some refinements needed for certification in time for first delivery at the end of the year," Kracht said in a telephone interview Thursday.
We'll is we will (i.e some time in the future).
We'll is we will (i.e some time in the future).
The A380 was already in production at the time of the Feb 2006 test. No modifications to the wings were required because it did not fail it's structural stress test. The entire point of the test was to gather data on what load the test wings (which are weaker than the production wings) failed at, which is why they intentionally broke the wings. The engineers then used this data to calculate the load limit that the production wings (which are stronger than the test wings) failed at. The calculated load limit for the production wings was above the EASA certification requirement, meaning the wings passed their test.
> The A380 was already in production at the time of the Feb 2006 test.
There is more than one version of the A380.
But there was no A380 Airbus with a 550 seat capacity in service at that time.
The whole point of that wing testing was so this newer, higher capacity A380 could get certification.
http://www.modernairliners.com/airbus-a380/airbus-a380_histo...
25 October 2007 - The first commercial flight of the A380 took place from Singapore to Sydney. All seats were auctioned off for charity.
FYI that link also shows the certification wing test failed:
14 February 2006 - Stress testing of the wing revealed that the wing broke at 146% of the required level instead of 150%. Further strengthening was added which increased the weight by 30Kg
There is more than one version of the A380.
But there was no A380 Airbus with a 550 seat capacity in service at that time.
The whole point of that wing testing was so this newer, higher capacity A380 could get certification.
http://www.modernairliners.com/airbus-a380/airbus-a380_histo...
25 October 2007 - The first commercial flight of the A380 took place from Singapore to Sydney. All seats were auctioned off for charity.
FYI that link also shows the certification wing test failed:
14 February 2006 - Stress testing of the wing revealed that the wing broke at 146% of the required level instead of 150%. Further strengthening was added which increased the weight by 30Kg
>There is more than one version of the A380.
There is only one version of the A380, the A380-800.
>But there was no A380 Airbus with a 550 seat capacity in service at that time.
I didn't mean "in service", I meant "in production". You're right that it wasn't in service at the time, but pieces of the plane had already been started to be produced, thus "in production".
>The whole point of that wing testing was so this newer, higher capacity A380 could get certification.
There was/is no "newer, higher capacity A380". This was the certification for the original (and only) A380.
We're just arguing semantics and talking past each other. During the test, the wings 'failed', but this failure was intentional. I see where you're coming from in your statement that it was a "failure", but my point is that the test passed, because the test did exactly what was needed to provide data for the necessary certification, which was achieved based on the test.
edit: edited to be less inflammatory
There is only one version of the A380, the A380-800.
>But there was no A380 Airbus with a 550 seat capacity in service at that time.
I didn't mean "in service", I meant "in production". You're right that it wasn't in service at the time, but pieces of the plane had already been started to be produced, thus "in production".
>The whole point of that wing testing was so this newer, higher capacity A380 could get certification.
There was/is no "newer, higher capacity A380". This was the certification for the original (and only) A380.
We're just arguing semantics and talking past each other. During the test, the wings 'failed', but this failure was intentional. I see where you're coming from in your statement that it was a "failure", but my point is that the test passed, because the test did exactly what was needed to provide data for the necessary certification, which was achieved based on the test.
edit: edited to be less inflammatory
Maybe you're not reading his quotes carefully enough. The wing failed at 146% of max design load which was BELOW the required failure limit of 150% which caused Airbus to add more structure to strengthen the wing.
https://www.ainonline.com/aviation-news/air-transport/2006-1...
QUOTE: Since manufacture of the initial wingset used in the tests, Airbus has refined the design, which will be slightly different on production rigs as a result of continued development, according to the European manufacturer. One factor may have been that earlier A380 weight-saving exercises had left no margin for error in the formal static load tests.
https://www.ainonline.com/aviation-news/air-transport/2006-1...
QUOTE: Since manufacture of the initial wingset used in the tests, Airbus has refined the design, which will be slightly different on production rigs as a result of continued development, according to the European manufacturer. One factor may have been that earlier A380 weight-saving exercises had left no margin for error in the formal static load tests.
> The entire point of these tests is specifically to break things
When you do these types of tests you are testing for a expected outcome.
If you do a test and the outcome is un-expected (i.e. the fuselage fails prematurely) it means your engineering and the expectations built around that engineering are wrong.
When you do these types of tests you are testing for a expected outcome.
If you do a test and the outcome is un-expected (i.e. the fuselage fails prematurely) it means your engineering and the expectations built around that engineering are wrong.
This is incorrect. These tests are specifically done because they want to gather data on what the failure loads (which are previously unknown) are.
No, as the Seattle Times pointed out the intent of the test is to ensure the wings support 150% of their rated load. They may continue until things break, but the typical purpose is simply to ensure there's that 50% wiggle room.
I'd rather it break in a stress test - than when I'm on it.
That's surprising since afaik it's a plug door that presses up against the airframe when under pressure. So sounds like a major failure of the door or the airframe itself.
"The test is meant to push the plane beyond its limits. Engineers had the plane pressurized and on the ground. They loaded it up well beyond capacity and bent its wings in an extreme manner, in a way almost certain to never happen in the real world."
"Dr. Curtis said this is not the time to race to conclusions, and it could be something totally innocuous that caused the door to come off. But it could cause delays. "It's unlikely this will speed up certification," he said. "It's more likely it will make the certification team, whoever's involved with Boeing and the FAA, do extra work to figure out what happened."
"Dr. Curtis said this is not the time to race to conclusions, and it could be something totally innocuous that caused the door to come off. But it could cause delays. "It's unlikely this will speed up certification," he said. "It's more likely it will make the certification team, whoever's involved with Boeing and the FAA, do extra work to figure out what happened."
"It's unlikely this will speed up certification."
I assume "this" in the above is equivalent to "the door blowing off the airplane".
I think we have a solid conclusion here, despite the previously stated desire to avoid racing towards them.
I assume "this" in the above is equivalent to "the door blowing off the airplane".
I think we have a solid conclusion here, despite the previously stated desire to avoid racing towards them.
I like how their PR person says "Safety is the highest priority at Boeing."
I feel like the reality is that "doing what our customers tell us so we sell more airplanes than Airbus" is their actual highest priority. I wonder how they fix that. I wonder if it's even possible for a publicly-traded corporation to do?
I feel like the reality is that "doing what our customers tell us so we sell more airplanes than Airbus" is their actual highest priority. I wonder how they fix that. I wonder if it's even possible for a publicly-traded corporation to do?
Personally, I think the onus is on the airlines to not buy unsafe airplanes. (Although, you do then get the argument of "why would they be incentivized to do so," which is admittedly a trickier question.)
They will probably add another door so if one blows off they have a spare already.
if safety was their biggest priority they would have grounded the max after their first accident. money is their biggest priority.
The front fell off. It's perfectly normal. They towed it out of the environment.
https://www.youtube.com/watch?v=3m5qxZm_JqM
https://www.youtube.com/watch?v=3m5qxZm_JqM
A wave hit it, ...in the sea? Chance in a million.
I was trying to find the right place to reply with that video. Classic skit humour.
I was trying to find the right place to reply with that video. Classic skit humour.
Actually he said "It's not very typical."
,,Investors were disappointed recently when Boeing announced delays in delivering its first 777X model into next year.''
,,Safety is the highest priority at Boeing."
I'm not sure if both of these sentences can be true at the same time. At the same time I wouldn't be a Boeing investor after how the MAX plane was designed.
,,Safety is the highest priority at Boeing."
I'm not sure if both of these sentences can be true at the same time. At the same time I wouldn't be a Boeing investor after how the MAX plane was designed.
That first quote doesn't have any citation. I guarantee this disappointment was never expressed by any large group of investors.
It's a headline-worthy story itself. "Investor X doesn't want you to be safe, just wants your money"
Take it with a grain of salt. That was added to manufacture anger.
It's a headline-worthy story itself. "Investor X doesn't want you to be safe, just wants your money"
Take it with a grain of salt. That was added to manufacture anger.
Well in the long term we’re all safer if Airbus has a competitor? /s
Thankfully we seem to have standardized on plug type doors, not outward opening ones, since the dc10 disaster. I wonder what happened.
Considering emergency exit doors, cargo doors and primary boarding doors are all plug design it must have been a serious failure.
https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10#Cargo_...
Considering emergency exit doors, cargo doors and primary boarding doors are all plug design it must have been a serious failure.
https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10#Cargo_...
This is pure ignorance on my part, but do plug type doors seal as strongly when on the ground ?
There is a mechanical latch, but they seal much better once the aircraft is pressurized and the door is being pressed into the frame.
If you look at the windows on a research submersible, the Plexiglas windows are cone-shaped and placed facing the opposite direction from those on a plane, as the pressure there is coming from the outside. Same reason - the cone shape means the pressure differential creates a tighter seal as it becomes greater.
Story time: I was once on a Northwest flight, and a passenger in the exit row behind me called a flight attendant back while we were still loading. It seems she could put her arm out of the aircraft through a gap in the over-wing door opening. Sure enough, I look out my window and there's her hand waving back at me. They call a mechanic who reseals the exit (applying a new safety-wire seal) and off we go to our destination.
It almost certainly would have sealed shut once we got to altitude. And probably did for some unknown number of flights before she discovered the problem. But I definitely felt better once it had been repaired.
If you look at the windows on a research submersible, the Plexiglas windows are cone-shaped and placed facing the opposite direction from those on a plane, as the pressure there is coming from the outside. Same reason - the cone shape means the pressure differential creates a tighter seal as it becomes greater.
Story time: I was once on a Northwest flight, and a passenger in the exit row behind me called a flight attendant back while we were still loading. It seems she could put her arm out of the aircraft through a gap in the over-wing door opening. Sure enough, I look out my window and there's her hand waving back at me. They call a mechanic who reseals the exit (applying a new safety-wire seal) and off we go to our destination.
It almost certainly would have sealed shut once we got to altitude. And probably did for some unknown number of flights before she discovered the problem. But I definitely felt better once it had been repaired.
One would presume this is purely a function of the pressure differential between the cabin and environment, which they presumably controlled for.
Doesn't sound like it.
"Engineers had the plane pressurized and on the ground. They loaded it up well beyond capacity and bent its wings in an extreme manner..."
"Engineers had the plane pressurized and on the ground. They loaded it up well beyond capacity and bent its wings in an extreme manner..."
I was responding to a question about the difference between being on the ground and in the air, not one about the many other differences between this test and real-world operation.
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They are plug doors, as with all other passenger jet airliners today. The door goes in at an angle (eg. 737) or part of it slides up/down (eg. 777) to fit through the door frame.
I can’t help to think that there is some force to attack Boeing for some reason. I remember a few years ago, several malfunctions on airbus to the point we decided to no longer use it in our fleet.
Anyways, there the undeniable effect of climate change / extreme weather. Planes have to catch up to security standards so no lives are lost. Silly to point fingers at companies like it’s their fault. Industry needs to move as one towards safety.
Anyways, there the undeniable effect of climate change / extreme weather. Planes have to catch up to security standards so no lives are lost. Silly to point fingers at companies like it’s their fault. Industry needs to move as one towards safety.
ok 1: the wings were bent in an extreme manner.
so you have a cylinder to a close approximation, with a hole in the side of it. Then you have two levers [wings] affixed to said cylinder, then you apply force to the levers, and distort the cylinder thus distorting the hole in the cylinder....
at this point i would invoke a toplogical parlour trick of making a quarter fall through a dime sized hole as an analogy.
https://prop-tricks.wonderhowto.com/how-to/do-large-coin-sma...
my hypothesis is that the entire airframe flexed causing the door frame to distort thus loosing its grip on the door panel, then FOOF! door goes away!
so you have a cylinder to a close approximation, with a hole in the side of it. Then you have two levers [wings] affixed to said cylinder, then you apply force to the levers, and distort the cylinder thus distorting the hole in the cylinder....
at this point i would invoke a toplogical parlour trick of making a quarter fall through a dime sized hole as an analogy.
https://prop-tricks.wonderhowto.com/how-to/do-large-coin-sma...
my hypothesis is that the entire airframe flexed causing the door frame to distort thus loosing its grip on the door panel, then FOOF! door goes away!
If you dont think this is the case then lets hear your critique, please tell me why you think this is not the case.
then if there is time left i can change my most recent actions in this thread
..."The test is meant to push the plane beyond its limits. Engineers had the plane pressurized and on the ground. They loaded it up well beyond capacity and BENT ITS WINGS in an extreme manner, in a way almost certain to never happen in the real world."
..."The test is meant to push the plane beyond its limits. Engineers had the plane pressurized and on the ground. They loaded it up well beyond capacity and BENT ITS WINGS in an extreme manner, in a way almost certain to never happen in the real world."
That was my thought as well, especially since the carbon fiber wings flex so much more. That flex might induce more stress on the wing mounts which in turn deform the cylinder. The good thing is that these test fixtures are fitted with lots of sensors that record all of the stress.
In my experience there are strain guages installed all over the air frame for testing and for operation, so the strain history of the frame can be reviewed.
The thing to keep in mind, is the different goals in testing engineered products like this.
there is a thing called Mean Time Before Failure [MTBF] that usually involves sampling of a number of units to arrive at a maintenance and replacement interval.
there is also a need to find the maximim service limits of a product, for example the swash plates and rotor linkage of a helicopter has a threshhold requiring at instance replacement. so for example, if you shook the yoke of a heli quickly left and right beyond a point you will probably knock yourself out of the air, but you will also induce damage requireing immediate replacement.
and then, there is what happened with the airframe of topic. immediate catastrophe during testing. I suspect this wasnt the immediate goal, as the engineers projected it would hold up, and were suprised, luckily not injured.
then the last thing that is usually a pre-production test, is an intentional induction of failure. you have a good idea when its going to break, and you take it there and beyond to gawp at the failure mode and the pieces, and re- engineer it until catastrophe is far beyond extreme duty conditions.[ideally]
The thing to keep in mind, is the different goals in testing engineered products like this.
there is a thing called Mean Time Before Failure [MTBF] that usually involves sampling of a number of units to arrive at a maintenance and replacement interval.
there is also a need to find the maximim service limits of a product, for example the swash plates and rotor linkage of a helicopter has a threshhold requiring at instance replacement. so for example, if you shook the yoke of a heli quickly left and right beyond a point you will probably knock yourself out of the air, but you will also induce damage requireing immediate replacement.
and then, there is what happened with the airframe of topic. immediate catastrophe during testing. I suspect this wasnt the immediate goal, as the engineers projected it would hold up, and were suprised, luckily not injured.
then the last thing that is usually a pre-production test, is an intentional induction of failure. you have a good idea when its going to break, and you take it there and beyond to gawp at the failure mode and the pieces, and re- engineer it until catastrophe is far beyond extreme duty conditions.[ideally]
[deleted]
> Former Boeing Engineer Dr. Todd Curtis runs Airsafe.com and said this doesn't happen often.
"Well the front's not supposed to fall off, for a start."
"Well the front's not supposed to fall off, for a start."
Wow, who would guessed - stress test broke the product in an unexpected way. Isn't this why we have stress tests in the first place?
..."The test is meant to push the plane beyond its limits. Engineers had the plane pressurized and on the ground. They loaded it up well beyond capacity and bent its wings in an extreme manner, in a way almost certain to never happen in the real world."
I almost didn't shit my pants when the door blew off.
I almost didn't didn't make it out of the burning building.
'Almost Certain' to never happen in the real world. Not very scientific to me. Sounds like PR talk.
I almost didn't didn't make it out of the burning building.
'Almost Certain' to never happen in the real world. Not very scientific to me. Sounds like PR talk.
Per the FAA (https://www.faa.gov/regulations_policies/advisory_circulars/...), the actual number for "Almost Certain to never happen" is no more than 1 loss of life per 10^9 flight hours. There's a real number behind that term, but not necessarily a stat that's accessible to the average news reader.
The goal is roughly that if you manage to hit some of these numbers, it's because things have already gone catastrophically wrong.
It's not feasible to ask for certain safety in all possible conditions. The only thing that can manage that is a bomb shelter with 50 parachutes.
It's not feasible to ask for certain safety in all possible conditions. The only thing that can manage that is a bomb shelter with 50 parachutes.
>it could be something totally innocuous that caused the door to come off
If making the door come off doesn't make the cause by definition not innocuous, then what are their standards for what is and isn't innocuous?
If making the door come off doesn't make the cause by definition not innocuous, then what are their standards for what is and isn't innocuous?
In this context, innocuous might mean something that would not have any meaningful chance of occurring in real-world operation, and should not have occurred during the stress test. So purely an artifact of the test, in other words.
Boeing can't seem to catch a break
ads. ads everywhere. it's almost impossible to read the article.
Pi-hole my dude. Makes local news sites actually readable.
So is it accurate to say Pi-hole blows the doors off your previous news consumption experience?
I've thrown many a phone because of the page jumping around as ads load. No more.
Blocks something like 25-30% of my web traffic.
Blocks something like 25-30% of my web traffic.
Nice, thanks for the reminder about pi-hole! Been meaning to set it up for so long now! :)
Try going there without Javascript. A lovely grey screen and nothing else!
Since using the Internet since 1992, this is the worst I have seen it.
Why are you not blocking them?
I use a curated hosts file and I don't see a single ad on that page.
KOMO is owned by Sinclair broadcasting now, which you can Google about and draw your own conclusions.
Stevvo(1)
test
[deleted]
Need a better source for this. Aviation Leak will probably have something better in a few days. What broke? Door? Doorframe? Fuselage around doorframe? Which door?
> "They loaded it up well beyond capacity and bent its wings in an extreme manner, in a way almost certain to never happen in the real world."
Here is another video of a 777 wing test where it broke at 154% of the [s/normal/maximum theoretical/] load - a bit beyond what was expected by the engineering team. https://www.youtube.com/watch?v=Ai2HmvAXcU0