Door blows out during ground test on Boeing 777X jet

[Bend alot]

Highlighting Boeing's resistance/reluctance to be transparent, no wonder other World regulators are looking like giving the MAX a good look over prior to a stamp.

Certainly some pressure needs to be put on the top management at Boeing to change path and stop heading for the cliff, while saying all is well every second day.

By the time it comes to the "final test" if you do not know the outcome in advance, it is just another game of cards - this aircraft is not a pioneer, it is using known materials and methods it is not experimenting with cutting edge technology or methods.

[Less Hair]

Not a pioneer? It's robot built CFRP-Wing and engines are the latest top technology on the market.

[Aihkio]

Surprising how things change with latitude, our beams change stiffness to the third power of height. (Sorry, couldn't resist.) Anyway stiffnesswise even small changes cause large results and it is beyond normal mortal intuition.

[ATC Watcher]

Originally Posted by Bend alot

H- this aircraft is not a pioneer, it is using known materials and methods it is not experimenting with cutting edge technology or methods.

But it follows the same pattern as with the Max, i.e. stretching an existing air frame possibly a bit (too?) far.
Changing structural elements' material composition and thickness to gain space and weight looks wonderful on paper I am sure.

Anyway the key figure we miss here is at what percentage of what ( pressurization or wing bending,) the door failed , if it is close or above to 150% there might be nothing much to write about.
I remember the A380 wing failed at 145% , which was , according Airbus : " within 3% of the set 1.5 limit " and therefore deemed acceptable by the regulator .

[Bend alot]

Originally Posted by Less Hair

Not a pioneer? It's robot built CFRP-Wing and engines are the latest top technology on the market.

Robot building is not new or cutting edge if you put BS in, BS comes out - it should be a step forward not backwards. The first 777 passed the test no problem (many years ago).
Wings are not a massive design/construction difference from the 787.
Engines (not made by Boeing) have been used as the excuse to delay - Gas turbines are not new, extracting the last % from them is not new either (yes it is very big, but so is the A380).

The 777X is not much different to a change from a 737 classic to a 737 NG (hopefully not a MAX) as a comparison. It is simply tweaking current and past technology.

After all it is using grandfathering, so a pioneer it is not - just a sibling.

The 747 was a pioneer but the A380 was not

[Less Hair]

Folding wingtips on the 787? If you go into details technology IS pioneering. That is why the engines have teething troubles.
Admittedly not so much the fuselage.

[Bend alot]

Originally Posted by Less Hair

Folding wingtips IS pioneering.
.

Certainly for an aircraft designed in the 21st century, exactly the same pioneering level as a moon landings in the 21st century.

The mechanics and materials even design is not new.

[Deepinsider]

Originally Posted by Bend alot

Certainly for an aircraft designed in the 21st century, exactly the same pioneering level as a moon landings in the 21st century.

The mechanics and materials even design is not new.

That's true, But what is new, is that same old design (" The first 777 passed the test no problem (many years ago").
is now being pressurised to a HIGHER LEVEL to satisfy marketing policy that the cabin alt will be lower, similar to
the 787.
Somebody here will tell us the pressure differential increase I'm sure.

[Bend alot]

Originally Posted by Deepinsider

That's true, But what is new, is that same old design (" The first 777 passed the test no problem (many years ago").
is now being pressurised to a HIGHER LEVEL to satisfy marketing policy that the cabin alt will be lower, similar to
the 787.
Somebody here will tell us the pressure differential increase I'm sure.

Yes exactly and since the original 777 there have been great advancements in mathematics, it has been hard for most to keep up.

[DaveReidUK]

Originally Posted by Deepinsider

Somebody here will tell us the pressure differential increase I'm sure.

The difference between a 6,000' and 8,000' cabin [ISA] is 0.86 psi, so a 150% proof test would require about a 1.3 psi difference.

[Deepinsider]

Originally Posted by DaveReidUK

The difference between a 6,000' and 8,000' cabin [ISA] is 0.86 psi, so a 150% proof test would require about a 1.3 psi difference.

We all know only too well with the kid's balloons what happens with that 'last extra puff'

[Jim59]

Quote:

Originally Posted by Deepinsider Somebody here will tell us the pressure differential increase I'm sure.

The difference between a 6,000' and 8,000' cabin [ISA] is 0.86 psi, so a 150% proof test would require about a 1.3 psi difference.

Assuming no increase in ceiling.

[golfyankeesierra]

But why are they still doing these test in the first place?
I thought the airplane should have been flying already, if it only wasn’t for engine troubles beginning this year?
Apparently the tests were overdue already. Boeing is not telling everything here.

[Sailvi767]

Originally Posted by golfyankeesierra

But why are they still doing these test in the first place?
I thought the airplane should have been flying already, if it only wasn’t for engine troubles beginning this year?
Apparently the tests were overdue already. Boeing is not telling everything here.

Many test can and normally are done concurrently with flight testing. As a example the A380 first flew in Apirl of 2005. The wing failed testing in Feb of 2006.

[Speed of Sound]

Originally Posted by golfyankeesierra

I thought the airplane should have been flying already, if it only wasn’t for engine troubles beginning this year?
Apparently the tests were overdue already. Boeing is not telling everything here.

Not necessarily.

The engine delay may have allowed the testing to be rescheduled to fit the extended gap, taking pressure off those doing the testing and allowing more time for fixes if needed.

[FullWings]

...Boeing went on to emphasize that “the testing conditions were well beyond any load expected in commercial service” and that the plane used in the test “will never fly or be used in passenger service.”..

Given that they likely have more lawyers than engineers at Boeing these days, reading between the lines it might have failed above normal max diff but below certification limits...

[golfyankeesierra]

Sailvi and SoS, thanks. Glad that there is no reason to be suspicious.

[fdr]

Originally Posted by Bend alot

The 747 was a pioneer but the A380 was not

I would have thought that the use of a ceramic composite skin was pioneering on the 380. It certainly raised some interesting papers on interstitial corrosion and the attendant forces that develop within a laminate. The 787 was also up there with dealing with composite repairs in the field from ramp rash etc.

[wiedehopf]

In regards to the A380:
5000 psi instead of 3000 psi is sort of pioneering, at least in regards to civil airliners.
So is gust alleviation by controlling individual aileron panels.

[Smythe]

Folding wingtips on the 787? If you go into details technology IS pioneering.

Folding wingtips have been an option on the 777-300 since it was introduced. (2004)

Boeing was so sure airlines would buy it that the first 150 or so aircraft had the mechanism built into the wings.

Not a single airline ordered the option.