
Door blows off Boeing 777X during stress test - ephesee
https://komonews.com/news/local/door-blows-off-boeing-777x-during-stress-test
======
cyberferret
It's a stress test. You would _expect_ things to break during a stress test.

> "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](https://www.youtube.com/watch?v=Ai2HmvAXcU0)

~~~
kbenson
> 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.

~~~
cameldrv
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.

~~~
cmurf
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.

~~~
cameldrv
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.

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org3432
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.

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Aloha
"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."

~~~
bob1029
"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.

~~~
fastball
What is the solid conclusion?

~~~
jethro_tell
That it is unlikely to speed certification

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jrockway
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?

~~~
BalinKing
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.)

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clebio
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)

~~~
ehnto
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.

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xiphias2
,,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.

~~~
master-litty
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.

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jumelles
Everything Boeing does now is going to be put under a microscope by the press
(at least) for probably years to come.

~~~
ulfw
And rightfully so. Look where not paying attention has led to.

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walrus01
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_...](https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10#Cargo_door_problem_and_other_major_accidents)

~~~
yial
This is pure ignorance on my part, but do plug type doors seal as strongly
when on the ground ?

~~~
DavidSJ
One would presume this is purely a function of the pressure differential
between the cabin and environment, which they presumably controlled for.

~~~
fastball
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..."

~~~
DavidSJ
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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lanevorockz
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.

------
rolph
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...](https://prop-tricks.wonderhowto.com/how-to/do-large-coin-small-hole-
trick-319800/)

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!

~~~
rolph
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."

~~~
donarb
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.

~~~
rolph
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]

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banannaise
> 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."

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yotamoron
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?

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erikig
..."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."

~~~
frankharv
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.

~~~
karthikb
Per the FAA
([https://www.faa.gov/regulations_policies/advisory_circulars/...](https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22680)),
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.

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Causality1
>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?

~~~
DavidSJ
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.

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Havoc
Boeing can't seem to catch a break

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bombela
ads. ads everywhere. it's almost impossible to read the article.

~~~
huffmsa
Pi-hole my dude. Makes local news sites actually readable.

~~~
davidkuhta
So is it accurate to say Pi-hole blows the doors off your previous news
consumption experience?

~~~
huffmsa
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.

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nmfert
test

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Animats
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?

