https://avherald.com/h?article=4b4e8ca7&opt=0
I would not be surprised if the whole fleet of this type/engine gets grounded for some time.
https://en.wikipedia.org/wiki/Korean_Air_Flight_2708?wprov=s...
[0]: https://en.wikipedia.org/wiki/Southwest_Airlines_Flight_1380
As one commenter put it, to an ER doctor this is a shallow wound with lots of blood.
[0] https://www.pprune.org/rumours-news/638797-united-b777-uncon...
Nothing bad happening, everyone uninjured and a plane making an orderly airport emergency landing is many layers of safety systems all working properly.
Airplanes are big fragile inflated sausages, and it takes relatively little by way of explosive to down one. An early model (the de Havilland Comet, operated by BOAC and South African Airways in the 1950s) was downed due to a design flaw leading to metal fatigue around the windows, with three aircraft lost in 12 months due to in-flight break-ups, 99 souls lost.
Even at lower altitudes, an uncontained fan or turbine failure can be rough on the cargo or passengers, either from direct shrapnel, decompression, or (partial or full) egress.
[0] https://aviation.stackexchange.com/questions/45566/how-thick...
WW2 fighter planes anyone?
Saying that, resultant vibration causing the inlet and nacelle cowling to separate isn’t supposed to happen either - because of the serious risk to the tail.
2018: United 777 same PW engine (seems very similar but without fire) https://www.youtube.com/watch?v=O-_IAKCBTxc&t=10s
2016: KAL 777 same PW engines (aborted takeoff after engine failure) https://www.youtube.com/watch?v=9bHrW_34kAk
All planes had zero casualties.
Objects drop from aircraft all the time, daily. It isn't generally newsworthy unless part of a larger story. And even then, only if the object is found and recognized as being from an aircraft. Small rocks also fall daily from space, probably more by weight than aircraft-related objects, yet virtually nobody ever gets hit by space rocks.
That being said, there was a russian spacecraft that disintegrated and hit someone house, in the middle of siberia bo less. So it does happen, but its freak ecen3ts territory.
https://en.wikipedia.org/wiki/Intelsat_708
https://arstechnica.com/science/2019/11/china-keeps-dropping...
"It has happened many times before, including most infamously in 1996 when a Long March 3B rocket veered off course shortly after a launch and crashed into a village. Chinese officials reported six dead from the accident, although Western sources have speculated that hundreds of Chinese citizens may have died in the accident."
Could you proofread and type correctly so we understand what you're saying? I can't read all of what you're saying.
Sort of. The possibility of some types of failure is anticipated in the design of other parts of the engine. But there are also inspection procedures in place to ensure that engine parts that might fail are replaced before they fail. A report on a previous incident in Feb 2018 (referred to upthread) says that the root cause was a cracked engine fan blade that should have been detected on a previous inspection but wasn't. Failures that are supposed to be prevented by inspection and replacement of parts are not necessarily also allowed for in other parts of the design. So it's quite possible that luck is involved here as well and that a future failure of this type could have much worse consequences.
(A380 "blade off" test, rare footage of giant engine failing)
No, they're not. Fan blade cracks are expected; and fan blades are inspected for cracks so that the blades can be replaced before they fail.
Yes, it's also true that, as a second line of defense, engine housings are designed to contain failed blades. But the overall risk of the system is calculated on the assumption that that is a second line of defense, not the only line of defense. In other words, it's calculated on the assumption that a fan blade failure in flight will not be due to a crack that could have been detected at the last inspection but wasn't. It's calculated on the assumption that a fan blade failure in flight will be due to some other root cause that nobody has ever seen before. In other words, we have second lines of defense because we don't presume that we know about all possible root causes for a given failure. We don't expect fan blades to fail, but just in case one does due to some root cause we didn't know about, we design an extra layer of protection.
But what happened here is that an inspection regime designed to catch a root cause we do know about, failed to catch it. That's not within the design parameters of the system.
You still are not addressing my point.
Of course inspections cannot be relied upon to prevent failures due to root causes that are not known prior to the incident.
But inspections are relied upon to prevent failures due to root causes that are known. And that's what failed to happen in this case.
Put it this way: by your argument, the NTSB's final report on this should be something along the lines of "this was an expected failure and the containment worked, so no corrective action needs to be taken". Do you really think that's what will happen?
Whereas by my argument, the NTSB's final report on this will be something along the lines of "the inspection process failed to properly catch a cracked fan blade, and corrective actions A, B, and C need to be taken to fix the process".
There's some good video off the current one on the BBC site https://www.bbc.com/news/world-us-canada-56141673
One thing that does bug me, though is that we now have two events where the shroud was lost. Were these uncontained failures (problematic because of potential for wing damage) or contained faiLures followed by aerodynamic shedding of the damaged shroud (system functioning as designed). I'm also somewhat concerned about the fire remaining in the burner stage. Might have just been lubricants, but I'd want to make sure the fire handle had been pulled and investigate whether it worked correctly.
But in that type of failure, you can't control where the pieces go.
https://abc7ny.com/philadelphia-emergency-landing-southwest-...
It resulted in depressurization and partial ejection/death.
"Two small punctures were found in the right side fuselage just below the window belt with material transfer consistent with impact from pieces of an engine fan blade"
(From the link in parent to this thread https://avherald.com/h?article=4b4e8ca7&opt=0)
However, loss of the shroud doesn't necessarily imply there was a confinement failure. Damage to the shroud during the event can easily lead to the cowling shedding aerodynamically, which is also part of the design: the last thing you need is more drag on the dead engine side. We can't tell which that was in this case, but it's important that we do---the design criteria specifying that the aircraft can be safely recovered from a catastrophic single engine failure during any stage of flight would assume the failure is confined to the engine.
Some cheap airlines might ignore those rules, but none in the US. (Only the poorest, most corrup, countires in the world will ignore those limits)
https://en.wikipedia.org/wiki/Aircraft_maintenance_checks#D_...
A commercial aircraft does not just accumulate wear and tear for 25 years until something breaks. They can basically fly indefinitely, but in reality after two or three D checks they are usually retired because the cost of the D check is more than the value of the aircraft.
In this case, something obviously went awry and it's both engineering, planning, and a miracle no one died or was crushed from debris from above. Regardless, comments like yours leave me feeling far more confident in this sort of thing.
Yes, though even something going wrong doesn't necessarily mean that we'd need to change any procedures.
Sensible procedures bring risks down to acceptable levels at an acceptable price. That level of risk is generally still more than 0%.
But yeah, a D check is so expensive I've heard there's a habit of dumping the aircraft on less observing flying companies some thousand miles before it comes up...
How is that safe unless you've got a production line doing it? Seems impossible to re-assemble it in the same way as it was done in factory...
And in a similar incident in February 2018 on a 777 (referred to upthread), one of those checks was found to have failed: the NTSB determined that the root cause was a cracked engine fan blade that should have been detected on a previous inspection (and that would have resulted in the blade being replaced), but wasn't. If this incident turns out to have a similar root cause, that means there are issues with the preventive inspection and maintenance process.
Unlike some codebases, aircrafts actually have mandated maintenance. Which is why most accidents are due to human error and not massive technical failures.
(That's a feature, not a bug! The pervasive checklists and general professionalism mean that most 'normal' human errors are recovered from without enough consequences to make it into the news.
So only the really unlucky and incompetent are what we usually hear about.)
We don't know yet.
There are hundreds of flaws. Aircraft are not perfect. Any large airframe sees lots of little things break every year. That's what inspections and maintenance are for. But the system is designed so that such things never add up into something really bad. Be worried about the aircraft without flaws. To me, that means it either never gets used or isn't being inspected properly.
Enjoy your flight and enjoy Denver. Get a donut from Voodoo for me.
* https://www.youtube.com/watch?v=O-_IAKCBTxc
Animated recreation with audio of this one (UA328):
* https://www.youtube.com/watch?v=G7-zh7Sebr8
* Via: https://forums.liveatc.net/atcaviation-audio-clips/ual-328-u...