Turbine disk failure is one thing that can down a plane, and you can only reduce the probability so much.
Fan blades and turbine blades can be contained by containment cases if they break off, but turbine disks can't. When a disk breaks, it's an uncontained engine failure. A 20 kg disk fragment flying at Mach 1 goes through everything.
Airframes are have a 30-degree fragment spread cone around every disk stage. Airframes are designed so that no single fragment can destroy all redundant systems at once in this zone (flight controls, fuel lines, and hydraulic systems). Jet fuel cannot be stored in the wings in this zone.
I admit that I glossed over the section on the machining of the oil pipe, but the facility appears to bear most of the blame.
These were pulled and scrapped from the whole A380 fleet.
"Investigators also criticized the culture within the Hucknall facility that manufactured the HP/IP bearing hubs, identifying signs of complacency and widespread procedural non-compliance. A paperwork review showed that the required signatures were missing from 131 out of 138 retrospective concessions issued between 2009 and 2011, and a large number of minor non-conformances had not been properly handled through the normal chain of command."
> Within the space of four seconds, the energy from the annulus gas flow accelerated the IP turbine past its critical speed, until centrifugal forces exceeded the ultimate strength of the nickel alloy disk. The red-hot, wildly spinning disk instantly fractured into several sections, which rocketed outward in multiple directions at incomprehensible speed.
> Jet fuel cannot be stored in the wings in this zone.
TFA describes a fuel leak resulting from a piece of the turbine disk passing through a fuel tank located within the wing:
"When the fragments of the IP turbine disk passed through the wing and belly of the A380, they caused considerable secondary damage along the way, not only to the №2 engine but also to the left wing fuel tank, which sprang a leak"
It also includes a photo of the inside of the damaged wing tank.
Was the requirement you describe added after this incident?
Seems close to impossible for existing designs. The wings are commonly almost entirely full of fuel at max fuel, and I doubt that taking the capacity hit is an option even in newly designed planes.
But it seems to me that the whole failure could have been prevented with a bunch of temperature sensors spread throughout the engine, and a good anomaly detection system.
The whole incident was because of 0.2mm offset in a machined part!
And the company that made the part ignored the quality compliance process was not fired. I wonder why - did Airbus think it’s their failure not to verify that the subcontractor adhered to procedures?
One of my favourite memories of flying Qantas when I was younger was the inflight entertainment.
If memory serves, they were celebrating some sort of milestone like "60 years without a fatal accident" or similar. Quite an impressive feat!
I'm unclear if it was directly related. But the Qantas inflight entertainment system on our flight from Sydney to Los Angeles meanwhile contained about 12 seasons of the National Geographic series "Air Crash Investigation" (Mayday: Air Disasters for Americans)
I will admit that show made an 18 hour slog of a flight significantly more enjoyable
> The detailed software allowed them to enter various parameters including the weather, runway condition, and any systems failures, and then calculate whether it was possible to land. But when everything had been entered, the program spit out an unhelpful answer: “no result.”
> When calculating the landing distance, the software applied a generic “operational coefficient” to account conservatively for variations in pilot techniques that could result in less efficient deceleration. The problem, as investigators would later discover, was that the software applied the coefficient again whenever another system failure was added. With so many system failures on the aircraft, the coefficient was applied a total of 9 times, resulting in a calculated landing distance considerably greater than the length of the available runway. However, Check Captain Evans was able to fix the problem by manually entering their actual landing weight, overriding the program’s assumption of a maximum landing weight. By specifying a landing weight in excess of the maximum, the system logic changed to apply the operational coefficient only once — for unrelated and obscure reasons — and lo and behold, when he ran the numbers this time, the computer said they could just barely land on any of the 4,000-meter runways at Singapore Changi Airport, with only 100 meters to spare.
This reeks so much of if-then-else programming as opposed to making a well-typed conceptual model computable.
Retroactive, but one thing that struck me since they were overweight for landing and their fuel dump was inoperative, why not turn on the leveling pump and pump fuel out the hole in the left tank anyway? It would have lowered weight and improved balance.
I got an impression from the text that pilots were not sure the fuel levelling line does not have a leak itself. Maybe they were afraid the line can leak fuel into fuselage somehow?
I once heard someone describe Admiral Cloudberg's air crash investigation blog as "the best thing on the Internet" and I still think that might be true. She is a great researcher and a superb writer, which stands out all the more these days in these fallen times of load-bearing AI slop. Her blog is beloved of both aviation geeks and, for obvious reasons, SREs (and other engineers).
She recently posted what's basically her magnum opus, on the Potomac river midair collision.[0] It's the length of a short book. I'm working my way through it; I'm taking a flight today, and I'll probably read it on the plane tonight.
This article, on how an A380 with 469 souls aboard almost crashed, but didn't, is one of her best. I like it because it's a happy ending, and a story of the combined effects of good engineering design (the astonishing degree of redundancy built into the A380 proved just enough to prevent catastrophe), and human troubleshooting under pressure in the cockpit by some smart people with vast experience who remained calm throughout. (Another favorite article of her, on the Air France 447 crash, tells the exact opposite story: poor systems design combined with pilots basically losing the most basic ability to aviate in the heat of the moment. That one is a much darker read.[1])
This remarkable event, along with the an accessible history of the evolution of precision manufacturing is covered in Simon Winchester's excellent book The Perfectionists[0]. The audiobook is narrated by the author, which is quite enjoyable as well.
per the article, because the stub pipe counter bore had to be drilled after that end of the pipe was welded in place, so directly measuring pipe wall thickness wasn't practical
Unbelievably comprehensive coverage from the Aviation Herald on this incident below, the owner of which was sued recently over a report to the point he sadly lost his home of over 40 years:
The plane was a significant factor but you really shouldn't look past the calibre of expertise in the cabin on this particular flight.
> 5 pilots were in the cockpit of this flight. In addition to the normal crew of pilot-in-command and co-pilot, there was an experienced relief pilot and two additional check captains; one was being trained as a check captain (CC) and the supervising CC, who was training the CC.
Captain Richard Champion de Crespigny had 35 years of flying experience at the time of the incident.
That is an insane amount of flight experience in the cockpit and all of the reports state this was a very significant factor. i.e by allowing distribution of the task load, plenty of time for one of the pilots to compute landing calculations manually etc.
THe A380 is a flying tank no doubt, but it wasn't the sole factor here - I think most people would agree this one was a shared victory.
Like Boeing, there was organizational dysfunction leading to a direct safety issue.
During the development of the A380, the German and French sides were using different versions of the CATIA PLM software (i.e. CAD), which prevented people from looking at a single unified model of the plane. One concrete problem it caused was major problems with the wiring harnesses, which led to a 2 year delay in the program, and 3 early A380's which couldn't be sold. (Airbus kept one for test, the other two got sent to museums)
That manifested in this accident because the wing wiring was routed through the engine disk burst axes (a hazard which is explicitly accounted for) with insufficient redundancy. That created the dangerous situation where they couldn't turn off the engine after landing.
The vastly preferable situation was to have redundant wiring that properly complied with regulations, which was retrofitted in an airworthiness directive (safety recall) after the accident.
They also required engine software that detected the sudden increase in speed associated with a shaft break and automatically cut fuel.
What’s the alternative? I think averaging with a dual input alert is a pretty good solution. Otherwise you need to find a solution to transition from one stick to the other. You can’t just switch sticks with the press of a button because the input could jump from elevator up directly to elevator down for example.
The state-held stakes are mainly French, German and (less) Spanish. The UK taxpayer currently owns 0% of Airbus, though the UK gets the business of building wings and landing gear.
I thought this was a strange insertion of geopolitics into the conversation so I checked out this account’s comment history. It’s good for others to see that some commenters here have a serious axe to grind and are not really “hackers” as their primary interest here. The most recent comments in order:
> [something about london taxi drivers, admittedly unrelated]
> I totally get you and in theory you are right.
And yet, in the USA you have gerrymandering and apparently _wanted_ Trump. Twice. Something has to be very wrong somewhere.
> I would suggest "lobbying" is not the correct word to describe all the corruption going on in the current USA administration cesspool.
>I recently bought a BambuLab 3D printer.
Designed and made in China. Right from the unpacking to first print the experience was top Apple-style quality. Indeed I was agreeably surprised.
> A global non USA success? Plenty. You might want to remove your pink USA glasses and look around. Spotify good enough for you?
> I am Canadian. Never, ever would i knowingly buy any dairy products from the USA , at any price.
We have cows too, and farmers.
> Its not that it hates its customers , as much as it it a USA-based company that is run under the rules made by the administration. Not that much different from running Red Star OS from North Korea, actually.
"Even the airplane itself ultimately survived: after a marathon repair that lasted 535 days and cost $139 million, the A380 Nancy-Bird Walton triumphantly returned to the skies in 2012."
This quote amazes me. My understanding is that Airbus, Qantas, and probably Rolls Royce were willing to spend this much because it meant that the incident was not a "hull loss" and therefore not as bad a hit to reputation and safety statistics. Does anyone know if that's true?
A new A380 is more expensive (rule of thumb half of official list price, so about $220 million), and airlines were not talking about retiring A380s yet at the time. So it even made economic sense.
The plane has since had a cabin upgrade and is still expected to operate at least until 2028. It’s operating SIN-LHR right now as I write this, currently flying over Azerbaijan.
Qantas is a troubled airline. Once a Qantas aircraft technician even told me that Singapore Airlines have a far superior maintenance schedule for their aircraft.
This person claims that he tells his family to avoid flying on Qantas ( but flies on it himself since he gets free flights)
These days Han airlines ( SIA, Cathay,China Eastern) and Middle Eastern airlines (Emirates,Qatar) are far better than Western Airlines ( American, British, Lufthansa, KLM,Qantas).
Please don’t post off-topic hearsay like this here. This article isn’t about maintenance, it’s about a manufacturing fault and the incredible work by the pilots to avert a colossal aviation disaster. Qantas continues to have an unblemished record of safety. Running airlines cost-effectively is a continually growing challenge. There is always a place for scrutiny of airlines’ maintenance and safety practices, but introducing it out of context and based entirely on an unverifiable comment from an unidentified individual is not a helpful contribution to this discussion.
Turbine disk failure is one thing that can down a plane, and you can only reduce the probability so much.
Fan blades and turbine blades can be contained by containment cases if they break off, but turbine disks can't. When a disk breaks, it's an uncontained engine failure. A 20 kg disk fragment flying at Mach 1 goes through everything.
Airframes are have a 30-degree fragment spread cone around every disk stage. Airframes are designed so that no single fragment can destroy all redundant systems at once in this zone (flight controls, fuel lines, and hydraulic systems). Jet fuel cannot be stored in the wings in this zone.
I admit that I glossed over the section on the machining of the oil pipe, but the facility appears to bear most of the blame.
These were pulled and scrapped from the whole A380 fleet.
"Investigators also criticized the culture within the Hucknall facility that manufactured the HP/IP bearing hubs, identifying signs of complacency and widespread procedural non-compliance. A paperwork review showed that the required signatures were missing from 131 out of 138 retrospective concessions issued between 2009 and 2011, and a large number of minor non-conformances had not been properly handled through the normal chain of command."
That's an oversight failure as much as a failure of that plant.
The oversight was at the plant.
Yes, but there are levels of oversight and this kind of thing should not be possible to hide. Someone on the official side of this messed up as well.
It is worse than even that:
> Within the space of four seconds, the energy from the annulus gas flow accelerated the IP turbine past its critical speed, until centrifugal forces exceeded the ultimate strength of the nickel alloy disk. The red-hot, wildly spinning disk instantly fractured into several sections, which rocketed outward in multiple directions at incomprehensible speed.
> Jet fuel cannot be stored in the wings in this zone.
TFA describes a fuel leak resulting from a piece of the turbine disk passing through a fuel tank located within the wing:
"When the fragments of the IP turbine disk passed through the wing and belly of the A380, they caused considerable secondary damage along the way, not only to the №2 engine but also to the left wing fuel tank, which sprang a leak"
It also includes a photo of the inside of the damaged wing tank.
Was the requirement you describe added after this incident?
Seems close to impossible for existing designs. The wings are commonly almost entirely full of fuel at max fuel, and I doubt that taking the capacity hit is an option even in newly designed planes.
What's a turbine disc?
It’s explained in the article
But it seems to me that the whole failure could have been prevented with a bunch of temperature sensors spread throughout the engine, and a good anomaly detection system.
The whole incident was because of 0.2mm offset in a machined part! And the company that made the part ignored the quality compliance process was not fired. I wonder why - did Airbus think it’s their failure not to verify that the subcontractor adhered to procedures?
One of my favourite memories of flying Qantas when I was younger was the inflight entertainment.
If memory serves, they were celebrating some sort of milestone like "60 years without a fatal accident" or similar. Quite an impressive feat!
I'm unclear if it was directly related. But the Qantas inflight entertainment system on our flight from Sydney to Los Angeles meanwhile contained about 12 seasons of the National Geographic series "Air Crash Investigation" (Mayday: Air Disasters for Americans)
I will admit that show made an 18 hour slog of a flight significantly more enjoyable
Watching Mayday on flights is one of my favorite things to do for some odd reason.
Retroactive, but one thing that struck me since they were overweight for landing and their fuel dump was inoperative, why not turn on the leveling pump and pump fuel out the hole in the left tank anyway? It would have lowered weight and improved balance.
I got an impression from the text that pilots were not sure the fuel levelling line does not have a leak itself. Maybe they were afraid the line can leak fuel into fuselage somehow?
They got a warning that the fuel transfer system was damaged, so they decided not to use it, I think.
I once heard someone describe Admiral Cloudberg's air crash investigation blog as "the best thing on the Internet" and I still think that might be true. She is a great researcher and a superb writer, which stands out all the more these days in these fallen times of load-bearing AI slop. Her blog is beloved of both aviation geeks and, for obvious reasons, SREs (and other engineers).
She recently posted what's basically her magnum opus, on the Potomac river midair collision.[0] It's the length of a short book. I'm working my way through it; I'm taking a flight today, and I'll probably read it on the plane tonight.
This article, on how an A380 with 469 souls aboard almost crashed, but didn't, is one of her best. I like it because it's a happy ending, and a story of the combined effects of good engineering design (the astonishing degree of redundancy built into the A380 proved just enough to prevent catastrophe), and human troubleshooting under pressure in the cockpit by some smart people with vast experience who remained calm throughout. (Another favorite article of her, on the Air France 447 crash, tells the exact opposite story: poor systems design combined with pilots basically losing the most basic ability to aviate in the heat of the moment. That one is a much darker read.[1])
[0] https://admiralcloudberg.medium.com/reaping-the-whirlwind-in... [1] https://admiralcloudberg.medium.com/the-long-way-down-the-cr...
This remarkable event, along with the an accessible history of the evolution of precision manufacturing is covered in Simon Winchester's excellent book The Perfectionists[0]. The audiobook is narrated by the author, which is quite enjoyable as well.
[0]https://www.harpercollins.com/products/the-perfectionists-si...
Also this documentary is very good: https://m.youtube.com/watch?v=nZS-mkygGWI
I wonder why the engineers didn't specify a tolerance for thickness of the oil stub pipe?
per the article, because the stub pipe counter bore had to be drilled after that end of the pipe was welded in place, so directly measuring pipe wall thickness wasn't practical
Difficulty in measuring since it was machined after installation?
Unbelievably comprehensive coverage from the Aviation Herald on this incident below, the owner of which was sued recently over a report to the point he sadly lost his home of over 40 years:
https://avherald.com/h?article=43309c6d&opt=0
Context to the lawsuit brought up by Go2Sky: https://avherald.com/h?article=53c8958a
Catastrophic failure? Check
Plane landed without casualties? Check
Plane design so good it helped avoid casualties? Check
Hum... Ah! Not an american Boeing but a french Airbus. Of course.
The article mentions this story should make everyone a little less afraid of flying.
Sure, as long as its not on a Boeing plane.
The plane was a significant factor but you really shouldn't look past the calibre of expertise in the cabin on this particular flight.
> 5 pilots were in the cockpit of this flight. In addition to the normal crew of pilot-in-command and co-pilot, there was an experienced relief pilot and two additional check captains; one was being trained as a check captain (CC) and the supervising CC, who was training the CC.
Captain Richard Champion de Crespigny had 35 years of flying experience at the time of the incident.
That is an insane amount of flight experience in the cockpit and all of the reports state this was a very significant factor. i.e by allowing distribution of the task load, plenty of time for one of the pilots to compute landing calculations manually etc.
THe A380 is a flying tank no doubt, but it wasn't the sole factor here - I think most people would agree this one was a shared victory.
Like Boeing, there was organizational dysfunction leading to a direct safety issue.
During the development of the A380, the German and French sides were using different versions of the CATIA PLM software (i.e. CAD), which prevented people from looking at a single unified model of the plane. One concrete problem it caused was major problems with the wiring harnesses, which led to a 2 year delay in the program, and 3 early A380's which couldn't be sold. (Airbus kept one for test, the other two got sent to museums)
That manifested in this accident because the wing wiring was routed through the engine disk burst axes (a hazard which is explicitly accounted for) with insufficient redundancy. That created the dangerous situation where they couldn't turn off the engine after landing.
> That created the dangerous situation where they couldn't turn off the engine after landing.
Which is vastly preferable compared to all of the dangerous situations just prior to that landing.
The vastly preferable situation was to have redundant wiring that properly complied with regulations, which was retrofitted in an airworthiness directive (safety recall) after the accident.
They also required engine software that detected the sudden increase in speed associated with a shaft break and automatically cut fuel.
Read about the AF447 Rio-Paris crash. Input stick averaging?? That's a huge design mistake which contributed to the crash and AFAIK is still here..
What’s the alternative? I think averaging with a dual input alert is a pretty good solution. Otherwise you need to find a solution to transition from one stick to the other. You can’t just switch sticks with the press of a button because the input could jump from elevator up directly to elevator down for example.
You give them direct feedback and eliminate the need for this completely
An aviation thread with two utterly ignorant posts - [0]. Is that the aviation knowledge level of HN?
[0] - this one and https://news.ycombinator.com/item?id=49541946
Airbus is French, German and British. Not just French.
The state-held stakes are mainly French, German and (less) Spanish. The UK taxpayer currently owns 0% of Airbus, though the UK gets the business of building wings and landing gear.
I thought this was a strange insertion of geopolitics into the conversation so I checked out this account’s comment history. It’s good for others to see that some commenters here have a serious axe to grind and are not really “hackers” as their primary interest here. The most recent comments in order:
> [something about london taxi drivers, admittedly unrelated]
> I totally get you and in theory you are right. And yet, in the USA you have gerrymandering and apparently _wanted_ Trump. Twice. Something has to be very wrong somewhere.
> I would suggest "lobbying" is not the correct word to describe all the corruption going on in the current USA administration cesspool.
>I recently bought a BambuLab 3D printer. Designed and made in China. Right from the unpacking to first print the experience was top Apple-style quality. Indeed I was agreeably surprised.
> A global non USA success? Plenty. You might want to remove your pink USA glasses and look around. Spotify good enough for you?
> I am Canadian. Never, ever would i knowingly buy any dairy products from the USA , at any price. We have cows too, and farmers.
> Its not that it hates its customers , as much as it it a USA-based company that is run under the rules made by the administration. Not that much different from running Red Star OS from North Korea, actually.
> [Finally something unrelated]
"Even the airplane itself ultimately survived: after a marathon repair that lasted 535 days and cost $139 million, the A380 Nancy-Bird Walton triumphantly returned to the skies in 2012."
This quote amazes me. My understanding is that Airbus, Qantas, and probably Rolls Royce were willing to spend this much because it meant that the incident was not a "hull loss" and therefore not as bad a hit to reputation and safety statistics. Does anyone know if that's true?
A new A380 is more expensive (rule of thumb half of official list price, so about $220 million), and airlines were not talking about retiring A380s yet at the time. So it even made economic sense.
The plane has since had a cabin upgrade and is still expected to operate at least until 2028. It’s operating SIN-LHR right now as I write this, currently flying over Azerbaijan.
They paid an estimated $300M per aircraft, so even a $139M repair bill is worth it
Title is: A Matter of Millimeters: The story of Qantas flight 32 (2023)
Some discussion:
2023 https://news.ycombinator.com/item?id=38586773
https://news.ycombinator.com/item?id=49511213
Qantas is a troubled airline. Once a Qantas aircraft technician even told me that Singapore Airlines have a far superior maintenance schedule for their aircraft.
This person claims that he tells his family to avoid flying on Qantas ( but flies on it himself since he gets free flights)
These days Han airlines ( SIA, Cathay,China Eastern) and Middle Eastern airlines (Emirates,Qatar) are far better than Western Airlines ( American, British, Lufthansa, KLM,Qantas).
Please don’t post off-topic hearsay like this here. This article isn’t about maintenance, it’s about a manufacturing fault and the incredible work by the pilots to avert a colossal aviation disaster. Qantas continues to have an unblemished record of safety. Running airlines cost-effectively is a continually growing challenge. There is always a place for scrutiny of airlines’ maintenance and safety practices, but introducing it out of context and based entirely on an unverifiable comment from an unidentified individual is not a helpful contribution to this discussion.
Despite this, Qantas is consistently rated one of the top 3 safest airlines in the world every year.
Ah yeah, China Eastern..
https://en.wikipedia.org/wiki/China_Eastern_Airlines_Flight_...
Meanwhile Lufthansa had their last fatal crash in 1993. For British it was in 1976.