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Boeing 777X’s fuselage split dramatically during September stress test
- chiefalchemist 7y agoThis was in the related articles at the bottom. I wonder how the decision is related the test? I wonder how much say legal had. That is, if they end up in court is human-made easier to defend than robot-made? https://www.seattletimes.com/business/boeing-aerospace/boeing-abandons-its-failed-fuselage-robots-on-the-777x-handing-the-job-back-to-machinists/ https://www.seattletimes.com/business/boeing-aerospace/boein...
- garaetjjte 7y ago>And the interior of the plane was pressurized beyond normal levels to about 10 pounds per square inch — not typically a requirement for this test, but something Boeing chose to do. Hmm. Does it lower structural integrity, or improves it?
- sitkack 7y agoAnd is it likely to be a condition that a plane would experience during conditions like the test? Seems like it should nullify the entire test.
- v64 7y ago100% on the test is 150% beyond what would be expected from the absolute worst case real life scenarios. It would require extraordinary circumstances beyond what has been seen or modeled in reality to push an actual flight to these limits.
- TylerE 7y agoIt's pretty typical. If the cabin is pressurised to 6,000ft (standard in a 777) and the aircraft is at it's rated celing of 43,100ft, that's about a 9psi difference.
- lultimouomo 7y agoSounds like an airplane's Valsalva maneuver...
- tzs 7y ago> The relatively good news for Boeing is that because the test failed so explosively at just 1% shy of meeting federal requirements, it will almost certainly not have to do a retest. Regulators will likely allow it to prove by analysis that it’s enough to reinforce the fuselage in the localized area where it failed. I don't understand this. So they did a test, and it failed at 99%. They reinforce that one area where it failed, and show by analysis that the reinforced area would have made it to at least 100%. OK, but what about the rest of the fuselage? The rest was only tested to 99%. Couldn't there be another place that fails at, say, 99.5%, which wasn't detected in the first test because the place that fails at 99% stopped the test? Edit: I would guess that during this kind of test they have the plane heavily instrumented with things like strain gauges so they can understand how it reacts and see if it is behaving according to spec. So maybe it is the case that the data from the rest of the fuselage showed that it would have made it to 100% if the test had continued, and only the area that failed was in trouble. That could explain why they aren't require to do another test. That still leaves me unsatisfied, though. Presumably analysis of the design before the test said it would make it to 100%. If the failure was not due to a manufacturing defect in that particular fuselage, then it suggests that they analysis was not adequate. But then what assurance is there that their analysis that shows that the reinforcement would hold is good?
- capableweb 7y agoAbsolutely. I think Boeing has proven with these statements that they no longer care about safety or engineering standards. They should have continued to run tests to prove that they meet 150%, make a video of it and continue to run, in order to regain the trust of the public. But they seem unwilling to get back the trust. Also, I think this also shows that the interaction that Boeing have with the FAA and vice-versa, has been heavily corrupted by something (money?) and FAA is no longer trying to keep Boeing in check. They are trying to make sure that Boeing passes whatever certification even if they might miss some details.
- tlb 7y agoThe 100% already factors in a large safety margin.
- jackalo 7y agoDuplicate of previous day's: https://news.ycombinator.com/item?id=21648826 https://news.ycombinator.com/item?id=21648826
- jvanderbot 7y agoThis sounds fine. It's a catastrophic failure test. They push until it breaks, then it broke, and they were very close to their designed target (within 1%). If they had gone 1% past their designed target, they would have been upset, as they could have made the plane lighter. They were 1% short of design limit, they are upset because they'll have to add reinforcement. Have you seen the wing failure test? I worked for the company that did these tests (they did them before I worked there), and they still talk about how upset the engineers were that it went over spec in strength. https://www.youtube.com/watch?v=Ai2HmvAXcU0 https://www.youtube.com/watch?v=Ai2HmvAXcU0
- awalton 7y agoThe test on the Boeing 787 broke the load test machine - the composite wing was so strong, they literally couldn't break it. And let's just put this on record, so people can really shut up about this: The Airbus A380 failed at 145% maximum wing load. That's a full 3.3% below the safety margin. They did not retest, but did subsequently reenforce (just as Boeing is here). The plane was put into service by the FAA.
- neuronic 7y agoIt's always the same on HN. Some post about any news at Boeing, be they good, bad or whatever. Someone has to chime in and drag Airbus through the dirt at least once. Let's at least mention one issue regarding Airbus. Is this a sales platform? Really makes you wonder. Maybe it's just some weirdo mix of patriotism and capitalism.
- jvanderbot 7y agoYou missed the point completely. The point is: There's nothing wrong with being off target in these failure tests, and it's normal what happened in both cases.
- awalton 7y agoThis post didn't "drag Airbus through the dirt," it proved that there's no issue with the testing process at hand. Airbus did nothing wrong, nor did Boeing in this instance. Both "failed" to hit the target safety margin, took remediation steps, and did not retest. This is the system working as intended. The fact that you see this as somehow anti-Airbus is evidence of a personal bias.
- techslave 7y agoclick bait title. the plane basically passed. that is why a retest will not be required.
- jacobwilliamroy 7y agoPowerful destructive winds are only going to become more common over the next decade. Boeing really should do another test to make sure.
- jacquesm 7y agoWind is never going to make an airplane experience this level of loading. Think about it: an airliner going 900 kilometers per hour is flying into an apparent headwind of 900 kilometers per hour, much faster than any windspeed it is likely to encounter. The fastest winds that an airplane has to deal with are the tradewinds. The biggest risk to aircraft from high winds is during landing and when on the ground. On the ground these forces are not going to cause a crash (for obvious reasons) and during landing the bigger risk would be a wing strike or ending up next to the runway. In neither case would the strength of the plane as observed in these tests be a huge factor. What would cause such loading is a long dive or fall and subsequent recovery: https://en.wikipedia.org/wiki/China_Airlines_Flight_006 https://en.wikipedia.org/wiki/China_Airlines_Flight_006
- jacobwilliamroy 7y agoThanks for clarifying. I felt afraid when I first read this story, because of the recent unpleasantness with Boeing. Now I see that it's unlikely for this level of stress to occur.
- neonate 7y agohttps://web.archive.org/web/20191128190035/https://www.seattletimes.com/business/boeing-aerospace/boeing-777xs-fuselage-split-dramatically-during-september-stress-test/ https://web.archive.org/web/20191128190035/https://www.seatt...
- esterly 7y agoAlso a positive note, the carbon fiber wings bent 3x expected max >bent the jet’s giant carbon composite wings upward more than 28 feet from their resting position. That’s far beyond the expected maximum deflection in normal flight of about 9 feet >All this simulated the loads in a flight maneuver where a pilot would experience a force of 3.75 G, compared to the maximum of 1.3 G in normal flight >All this simulated the loads in a flight maneuver where a pilot would experience a force of 3.75 G, compared to the maximum of 1.3 G in normal flight
- baybal2 7y agoYep, and it is the fuse that broke, not the wing! The reason fuse has an "expiration date" set by the amount of pressure cycles is because aluminium breaks more due to microcracks and other metallurgical fatigues, than due to ductile failure. A composite lined fuse could've extended the life of an average airplane long beyond its moral obsolescence, and for this reason airplane makers are afraid adopting it.
- aidenn0 7y agoIt seems to me that if nothing ever fails short of the 100% test its probably overengineered, since the 100% already includes a significant safety margin. Alternatively if nothing ever fails the test, then they could also just stop doing these tests, since the analysis would already be shown to be sufficient.
- kitd 7y agoLol. Open the page, popup appears "Sign up for breaking news!"
- starpilot 7y agoVery impressive. They strengthened the fuselage to meet requirements almost exactly, and fell a tiny bit short. That's an incredible amount of optimization, that means there's hardly any excess material (weight). This keeps fuel costs low and airfares competitive.
- michaelmrose 7y agoWhen I fly I know I'm always pleased to know that my flight didn't cost an extra big Mac because the plane was excessively safe.
- perl4ever 7y agoExcessively safe meaning safer than the regulated margin of safety. Nobody really demands unlimited recursive safety margins.
- adrianN 7y agoBillions of people fly every year. Your single Big Mac might not have an impact for you, but billions of them can have an impact globally.
- WalterBright 7y agoAn overweight plane is a less safe plane.
- me_me_me 7y agoWell I have some bad news to you about bridges, dames, boats, rockets, and anything that is really expensive to make...
- basicplus2 7y agoWhat gets me is what is the point of a limit to test to if you are not going to enforce it. If 1% less is ok (Boeing) test to 1% less, if 3% less is ok (Airbus) make the limit 3% less. Not enforcing a limit smells bad and does not fill me with confidence. Strengthening the failure area will change the failure modes to other areas and may well make it fail at an even lower limit as other areas will be bending more to make up for the reduced deflection of the area that is strengthened. Not re-testing it after a design change like this worries me.
- zobzu 7y ago"we're not going to re-test. We failed the test but it was close enough" Yeah that makes me feel safe Boeing, real safe. Specially given your history now. Planes used to pass these tests with flying colors and they've been pretty safe. Have we forgotten already that planes used to break in half in the sky when there's heavy turbulence? 3.5G sounds like much, but it is also not that much. There's a reason why the test needs to be passed at a certain level, not just below. Heck otherwise, how about I pay 99% of my taxes, mortgage, pass 99% of my exams, etc. What is this? Note: before you read and trust the articles too much, airline planes have been WELL above 3.5G already in the real world. The fact that they're not supposed to go there does not mean they never do.
- iamaelephant 7y agoA lot of Boeing shills in this thread. Disappointing, but to be expected from an American company.
- dang 7y agoThe site guidelines explicitly ask you not to post like this. Would you please review them and stick to the rules when commenting here? https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html