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- Hacker News
- 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.by NetMageSCW
- 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?by vient
- 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?by dostick
- 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.
by quink - Veritasium put out a video recently about the incredible engineering in modern turbo fan jet engines, recommended watch if this thread has your interest :-)by arlattimore
- "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?
by adaml_623 - They paid an estimated $300M per aircraft, so even a $139M repair bill is worth itby shawabawa3
- One thing that might be taken into account is the delay between ordering a plane, and the delivery (can take up to 10 years), so 1.5 years and 139$ million is worth investing into, to keep revenue flowing earlier.by ygouzerh
- 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.by ahartmetz
- 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.
by crote - > 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.
by 00N8 - Infamously, https://en.wikipedia.org/wiki/American_Airlines_Flight_191#A...
This flight had a new system to allow passengers to see what the pilots saw. There's a chance that the passengers got to see the panic in the cockpit and watch their fates coming.
I have seen claims that this caused such systems to be avoided for a while.
by mrguyorama - 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
by userbinator - 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 was a scary one to read:
https://admiralcloudberg.medium.com/years-of-salt-and-metal-...
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.
by peterfirefly - 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.by trq01758
- 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!by jcalx
- 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
- Lol, I quite like the show and considered watching it. But then thought other passengers on the plane might see it and become a bit unsettled by it.
So last few times I opted for "To Catch A Smuggler". Still flight related but hopefully less unsettling.
by Insanity - That's hilarious. They don't think about "hey, maybe not show this, we might have nervous passengers"?by alex1138
- Watching Mayday on flights is one of my favorite things to do for some odd reason.
- 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:
- Context to the lawsuit brought up by Go2Sky: https://avherald.com/h?article=53c8958aby chinathrow
This reeks so much of if-then-else programming as opposed to making a well-typed conceptual model computable.> 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.by exceptione- well airbus does hire in morocco
inb4 you are racis Im moroccan
I personally know a guy who faked his entire university record (dad is a local politician) and is now working at engine systems at airbus in france
he does have a winning smile though
europe is not ready to deal with third world achievement dynamics
by likestowatch - reads like a glitch from Pokemon Red/Blue (Gen1). Even the simplest tests would have catched this issue.by Sweepi
- The A380 was designed >20 years ago, in the heavily regulated and safety-obsessed commercial aviation industry.
Any reason for assuming that your preferred solution would have been an available and comfortable option for the Airbus' lead engineers back then?
by bell-cot - 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.
by u1hcw9nx - What's a turbine disc?by polishdude20
- 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?
by Lumich