I flew on this exact same plane, VH-OQA, on November 4, 2019, from Singapore to Melbourne.
While I was sitting at the gate, I remembered that line from Rain Main about "Qantas never crashed," and since that flight would be my first time flying on an A380, I wondered if any had crashed or had any other incidents. I looked up "a380 crash" on my phone, and what do you know? The first hit was a Wikipedia article about a Qantas A380 uncontained engine failure, which had occurred four minutes after takeoff... from Changi! Even wilder was the fact that it had happened 9 years earlier. When I looked up the plane's registration number on Flightradar24, I realized that was the same plane I was flying to Melbourne on.
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."
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.
Don't know why you're getting faded out, because having worked on exactly this engine, software mitigations were put in place. That's exactly your `anomaly detection system`
It was a belt-and-braces fix, because the primary fix was of course to manufacture the engines correctly in the first place.
The "lots of temperature sensors" thing is actually easier said than done; jet engines already have lots of temperature sensors, and they will turn the engine off if a huge overtemperature is detected, but it's not a free win to add more of them. It increases the risk of a faulty sensor shutting down a perfectly good engine in flight, which from a safety-critical perspective is a borderline disaster condition all by itself.
(technically you usually cross-correlate temperature sensor readings with pressure sensor readings to prevent sensor faults turning engines off, but still, extra sensors isn't always a free win.)
> 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.
“It goes without saying that if any of the turbine fragments had entered the passenger cabin, there would have been injuries, if not fatalities, even if the plane later landed safely.”
The fact that it's assumed to have infinite energy when planning for this is crazy. Engineers saying yeah there is no material in the world that can stop it.
Infinite is a bit poetic there. For large enough n, n inches of (say) armor steel could stop it. But that suggestion got Sales talking about "commercially viability", and Finance sided with them, and we all know how that story goes.
It's not (purely) the sales and finance people, planes need to be able to get off the ground to be useful at all. I doubt even an A380 would still be able to lift off if you strap a dozen inches of armor plating to every part of the plane that could possibly be reached by shrapnel.
You'd put the containment armor directly around the engine. It wouldn't take dozens of inches. Whether you use Newton's rule of thumb (penetration ends when the mass of armor displaced equals the mass of the shell that hit it) or more modern rules - a failing turbine disk is neither a precision-engineered anti-armor weapon, nor a heavy battleship shell.
I'd bet the plane would still be able to take off, if it made it that far. But it never would - with the extra weight guaranteeing that no airline would buy it, Finance would never sign off on funding to even complete the design work.
(Yes, the reality behind my quips about Sales and Finance is more complex:)
Full containment is probably possible, but it would render the aircraft nearly useless, not just economically uncompetitive.
A 70kg chunk of nickel alloy is very dense, and at 800m/s , that’s 20 MJ. Thats about the same as 5kg of TNT, but focused on a small area.
For comparison, a modern 120mm artillery shell fired from a tank or similar field artillery has 10-20 MJ of kinetic energy.
A couple thousand kg of armour could likely contain that kind of energy, but it would also translate that energy to the engine mounts, wing, spar, and fuselage if it was not going to become a projectile itself. You could easily stop a fragment and critically damage a spar attachment, rupture a wing fuel tank, or end up with translational shock damage to any number of critical systems and structures. You’d probably have to double or triple your engineering margins of the entire aircraft, probably doubling the weight of the airframe.
So yeah, possible probably. But not on an aircraft designed to carry passengers or freight. It would be the biggest 6 seat aircraft ever built lol.
Interestingly, if you work backwards from that cargo capacity, you can arrive at a much smaller aircraft that could possibly feature full containment, because engine diameter and energy goes way down and containment starts to look much more practical. I would not be surprised if containment could be achieved in the small biz jet scale, with just significant sacrifices in cargo or range.
OTOH even the A10 warthog does not have full disk containment, and it’s probably the strongest candidate ever fielded for such a project… so, ymmv.
- which bear no resemblance to a failed turbine disk. And have about twice the muzzle velocity, which makes huge difference in penetrating a modern armour systems. Ditto their far greater density, vs. nickel alloy.
OTOH, your "A couple thousand kg of armour could likely contain..." seems too charitable. High-bypass jet engines are big. Beyond that, I'm more optimistic about mitigating shocks and such.
A critical parameter here - https://en.wikipedia.org/wiki/A380#A380F The freight variant was to have a 6,400 mile range carrying 150t of payload. So we could squander 25t per engine on disk containment and shock mitigation, and still have a 50t payload. Or a 3-digit passenger headcount.
Bottom line, there is no real-world difference between your "nearly useless" and my "disastrously uneconomical". Neither one will be designed, let alone built.
For the A10, I'd say military priorities would always block full disk containment - because every pound used for that is a pound they don't have for more weapons or munitions or range or armour or fuel or runway length or electronics or whatever. And over most of the 360 which disk fragments could exit a warhog's engines, there's nothing critical which they could hit.
I know we all like to hand wring about stuff like this but realistically it's "infinite" to prevent the same genius textbook engineers who cooked up the VMC procedure and the CMM procedure from cooking up equally half baked "with a plate of this thickness at this angle it will remove X energy from anything that penetrates it therefore we are good to put some super critical thing right in it's path" solution.
As it sounds like you have some knowledge about these engines, from the article:
“These [combustion] gases spin the [turbine] disk, which is attached by a drive arm to its associated drive shaft. The shaft then transfers the turbine’s rotational energy forward to the corresponding compressor at the front of the engine.”
I'm probably misunderstanding, but it sounds like the disk is attached to the shaft by a single so-called “drive arm”, which could be imagined to span maybe 10° on the circumference. I would have thought there'd be at least 3 such arms at 120° intervals, if not a continuous full 360° connection, which then I wouldn't call an arm. Could you clarify this point?
> 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.
> 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.
One reason is that this is mostly a brain firmware phenomenon. My personal observation is that some people are able to nail a domain with good conceptual integrity, but there are also many (clever) people that quickly reach to a mechanical implementation, often even unable to think on a conceptual level about the problem domain. Languages with proper sum types are really helpful here, but Haskell was 20 years ago already 16 years old.
Nonetheless, the language is not the real impediment, it is the way of approaching a problem. Also, the software we are talking about was a standalone application installed on laptops, they were not part of the airplane's board computer.
The "son of a politician takes a high level engineering position" story happens everywhere. If airbus has a strict hiring process I don't see any issue here. It's the same as people saying programmers from India are bad - I have worked with some incredibly skilled Indian programmers, literally top tier people(educated and living in India too, not immigrants educated elsewhere). You have all kinds everywhere, it's just what standard you want to set.
Morocco is notorious for its nepotism though. The run on Ceutta can't be unseen from the problem that for many young Moroccans pursuing an education is almost useless, as the opportunities are exclusively for the political elite. A whole generation does not see any future for themselves in their own country, which is very sad from my pov.
In India, afaik, a well-educated Indian has fairer chances. I don't know how much the current unemployment situation is playing out though.
Plane engines are extremely highly optimised, and the design margins are basically at the limit of what regulations allow, which is IMHO why the tiniest of errors can have huge consequences. However, in this case it sounds like the manufacturing process was such that it invited misalignment:
Finally, working from the inside through the inner hub counter bore, the stub pipe counter bore would be drilled to a specified depth to accommodate the filter. (This was the bore that was later found to be offset by half a millimeter.)
Why not machine the stub pipes to their desired dimensions, including the drilling, and then install them? That way, no in-situ drilling, with that accompanying risk of misalignment, would even be necessary. Even if they decided such drilling was unavoidable, a drill with a pilot (no pun intended) would've kept the holes as concentric as needed. (Disclaimer: Not a professional machinist; but have done some lathe and mill work.)
The temperature inside this buffer space was likely between 365 and 375˚C, well above the 280-degree auto-ignition temperature of the engine oil, so the spray immediately ignited.
It's worth noting that due to fire risk, most planes use non-flammable hydraulic fluid, although it's not without its own dangers, so perhaps non-flammable engine oil was considered but ultimately decided against: https://en.wikipedia.org/wiki/Skydrol
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
There's a podcast (that's been on "hiatus" for 6 years) that I used to listen to that would do an air crash segment. The show was called Hello Internet, and I would always try to queue up the air crash episodes for any flights I was on.
One of the hosts recently started a new podcast called Runway 23 that's mostly about air crashes, and his cohost is actually a Qantas pilot.
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])
Going to plug her Patreon (https://www.patreon.com/Admiral_Cloudberg) here because her articles are extensively researched and consistently well-written, and I enjoy reading them, and hope to continue reading new ones in the future!
It baffles me that that airlines can run so well on check lists and procedures instead of thinking and understanding. This is a case where just a tiny bit of understanding on the part of the mechanics would have avoided a crash and two deaths.
I would also highly recommend checking out Mentour Pilot channel on youtube as she is the writer for some episodes. Accident videos there have interesting technical details.
> the in-flight entertainment system, which featured a live view of the aircraft from a tail-mounted camera. The digital stream clearly showed a much more literal stream of fuel pouring from the left wing and into the aircraft’s wake, which was also visible with the naked eye from the lower deck. Johnson proceeded down to check for himself, at which point he also observed for the first time that there were two gaping holes in the top of the left wing, surrounded by jagged metal, where the turbine disk fragments had exited.
> According to Check Captain David Evans, the cabin crew were concerned that so many passengers were watching the live feed from the tail camera, but in a collective decision, the pilots elected not to turn it off because, in their view, the feed suddenly cutting out would probably be more alarming than anything that could be seen on it.
I appreciate this part. If I were ever in a similar situation, I'd want to be able to see what's going on. Suddenly cutting the feed would send me straight into a panic.
I helped do the video recording and the website for the 2013 International Forum on Quality & Safety in healthcare that was held in London at the Excel Center.
One of the talks there was from Qantas Senior Check Captain David Evans, "Teamwork Under Duress" there, which was all about that flight and what happened.
It was an amazing talk, and I have a huge amount of respect for the job that airline pilots do.
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?
This feels more like engine manufacturer QC rather than anything Airbus.
Because also, from Wikipedia: On 22 June 2011, Qantas announced that it had agreed to a compensation of AUD$95 million (£62 million/US$100 million) from Rolls-Royce. - skipping Airbus entirely.
The whole business of airliners engines is fascinating in its own.
AIUI when you're buying a plane from Airbus, it's possible/frequent to own the _airframe_; but not the engines — the engines are often _leased_ (sometimes directly from RR/GE); I've even heard of cases where each engine will be owned by a different entity!
Veritasium put out a video recently about the incredible engineering in modern turbo fan jet engines, recommended watch if this thread has your interest :-)
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?
Can anyone explain why on earth you would counter bore a pipe at all, let alone after installation? I read the article but couldn’t understand the explanation. It seems like a totally ludicrous way to make a pipe.
The counterbore accommodates a filter element. Maybe they were worried it could change the interference fit if they drilled them before installation, or wanted the swaging effect.
It's probably significantly easier to machine it this way. The pipe is curved, so work holding isn't straightforward. Once the blank is installed in its place in the bearing chamber face then you can just move that larger part around to machine all the features in it, including the counterbore.
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.
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:
That's disturbing. Ironically, the article in question was published July 4th last year. Note that the bar for defamation is a lot higher in the US than many other countries: https://en.wikipedia.org/wiki/Defamation#United_States
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
"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?
Qantas has never had a hull loss in the jet age. Its last fatal accident was with a 10-passenger propeller plane, back in 1951. It is widely regarded as the world's safest airline.
Being able to keep this "never lost a jetliner" / "no accident we couldn't fly away from in 75 years" marketing claim is worth a lot. It's also why Qantas Flight 1 (1999, runway overrun of a 747-400, no significant injuries), despite initially being a write-off, was repaired for over AU$100M and returned to service.
One thing that might be taken into account is the delay between ordering a plane, and the delivery (can take up to 10 years), so 1.5 years and 139$ million is worth investing into, to keep revenue flowing earlier.
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.
The absolutely insane thing about it is not even the accident itself (most airlines have had accidents) but the way it is handled in their equivalent of FAA and the government. From how they delayed issuing the visas for Boeing and other representatives to how they STILL have not released a report.
great example of why I would avoid any PRC airline if I can help it.
(Presumably one reason they don't want to release the report is because it would lead many others to do the same and they want to protect their airline profits, but of course it ensures that the problem will not be fixed the longer they delay it)
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.
It was probably helped by the fact that airbus didn’t try to pretend that the aircraft was just a slightly different version of some previous aircraft and therefore doesn’t require any additional training lol.
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.
Sort of. Rolls Royce voluntarily developed this software modification in response to learning that their reasoning about it never being able to happen was incorrect and being unable to concretely account for how it happened. EASA, which was not even the relevant safety authority for this incident, upon learning of its existence, only then required it to be installed on all A380 Trent 900 engines.
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.
While I was sitting at the gate, I remembered that line from Rain Main about "Qantas never crashed," and since that flight would be my first time flying on an A380, I wondered if any had crashed or had any other incidents. I looked up "a380 crash" on my phone, and what do you know? The first hit was a Wikipedia article about a Qantas A380 uncontained engine failure, which had occurred four minutes after takeoff... from Changi! Even wilder was the fact that it had happened 9 years earlier. When I looked up the plane's registration number on Flightradar24, I realized that was the same plane I was flying to Melbourne on.
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