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.

No indication of what the test criteria were, if any. Some tests, especially those past design limits, are just for informational data.

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.

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."

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.

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.

And yes it did eventually pass that wing test only because if it had not it would not never have been certified.

I suggest you read it. The A380 did not fail. It says so in the link you provided.

We'll is we will (i.e some time in the future).

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 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

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.

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.