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It's amazing to me that modern aircraft engineering is so good that an engine can lose its fan blade entirely at 35000 feet and the plane can still continue on

It's amazing to me that modern aircraft engineering is so good that an engine can lose its fan blade entirely at 35000 feet and the plane can still continue on for 2 hours and safely land. An uncontained failure like this is the worst kind, and I know it could have gone worse, but it didn't and that amazes me. I wonder if the cowling contained the initial disintegration but was removed in the process. I'm not an engineer, but from the way that looks and the fact that nothing flew off and did further damage makes me at least wonder if that's what happened.

CydeWeys 9y ago
The A380 has four engines in total, and can easily tolerate the loss of just one in normal flight. Adding more engines has been a basic way to increase reliability since the beginning of the field; it's not just modern aircraft engineering. There's no other part of the airplane behind the engines either, so nothing to be hit by debris. What amazes me more is that the newest twinjets are now considered reliable enough to fly six hours away from the nearest landing strip -- that's how far they can coast on the single remaining engine if necessary!
- inamberclad 9y ago
  It's not really coasting. A transport category aircraft is required to have enough power to continue climbing if it loses an engine, so it must also have enough power to maintain level flight indefinitely (barring fuel consumption, oil leaks, or mechanical damage from an engine failure)
  - CydeWeys 9y ago
    I meant to say "cruise", if that makes more sense.
    - KGIII 9y ago
      If it is any consolation, I knew what you meant. Otherwise, you'd probably have said something like glide and the glide ratio of the big planes isn't very good. Out of curiosity, I just checked for the A380 and the best guess is 15:1, so it does glide better than I expected, but still not that far. Google tells me that it'd glide ~130 miles if it had a starting altitude of 45,000'. That's better than I expected.
      - katastic 9y ago
        According to this: https://en.wikipedia.org/wiki/Gliding_flight#Aircraft_.28.22gliders.22.29 https://en.wikipedia.org/wiki/Gliding_flight#Aircraft_.28.22... The 747-200 also has a glide ratio of 15:1. I can't tell if that's amazing, good, or average. A sailplane can have up to 60:1! That's pretty impressive! According to this: A "clean A320" has 17:1. Neat. https://aviation.stackexchange.com/questions/14814/could-a-commercial-plane-like-airbus-a320-glide-with-no-working-engines-from-110 https://aviation.stackexchange.com/questions/14814/could-a-c... Something I never knew was this: >As someone said above, you have to remember, pretty well all descents are done with the thrust at idle. So I imagine the glide ratio is pretty important for all-purposes of flight and not just when engines go out.
        KGIII 9y ago
        You descend at just about the stall speed. It's pretty close to the slowest the individual plane can go before losing lift. I believe the term for coming in with no lift, purely gliding, is called dead stick. A Cessna 172 is worse, for comparison. I believe they are just 9:1. I guess it improves if you stop the prop entirely. I assume it is less drag.
        tyw 9y ago
        best glide (converting altitude into the maximum distance) speed is quite a bit higher than the stall speed and found at the lift/drag max. minimum sink (converting altitude into the maximum time) is usually found about halfway between best glide speed and stall speed. http://learntoflylv.com/drag%20curve.gif http://learntoflylv.com/drag%20curve.gif
  - dominotw 9y ago
    >A transport category aircraft is required to have enough power to continue climbing Can a plane takeoff with just one engine ?
    - hlandau 9y ago
      Yes. Twinjet airliners must be able to take off if one engine fails at or after V1.
      - FabHK 9y ago
        Which, incidentally, means that twins are quite powerful - a twin has 100% more engines (thus, power available) at takeoff than needed, while a quad has 33% more. Thus a twin has 50% more power than a similar 4 engine. At least conceptually-ish.
- timb07 9y ago
  Actually, adding engines increases resilience, or the ability to tolerate failure. The extra complexity of extra engines actually reduces reliability, since there are more components that can fail.
  - FabHK 9y ago
    As the saying goes: If you have an engine failure in a twin, the remaining engine has enough power to take you to the scene of the accident.
- WalterBright 9y ago
  > There's no other part of the airplane behind the engines either, so nothing to be hit by debris. The fans spin very fast, and will fly out radially, not just fall back. They'll slice right through anything they contact. The Airbus flight was very, very lucky.
  - cialowicz 9y ago
    The engines are designed so that a detached fan blade stays contained within the cowling. Here's a video of a fan blade containment test on a Rolls Royce Trent 500: https://youtu.be/RIOWjhjC1jM https://youtu.be/RIOWjhjC1jM
    - KGIII 9y ago
      I guess they use really, really precise timing and explosives to knock one blade loose in order to do the containment tests. They want it to come loose at a specific point in the revolution. The documentary didn't say why they wanted it to be at such a specific place, only that they did. I've long since forgotten the margin of error, but it was very small. You probably noticed that the individual blade is painted a different color and is different colors. My recollection is that they use the multiple colors because they do very high definition recording and the colors are all in different areas of the spectrum, so they can observe it better as the thing tends to be quickly obscured by fire and smoke. I probably do watch too many documentaries.
      - dba7dba 9y ago
        > I probably do watch too many documentaries. You are not alone. I actually watch more and more documentaries than movies or TV series. Reality is even stranger than fiction often.
        KGIII 9y ago
        It has been great to see the proliferation of documentaries on the web. Streaming services have been a great thing for me. I watch documentaries pretty much to the exclusion of all other genres, except American football. Even if I'm not actively paying attention, I'll frequently have a documentary playing in the background. It's not a scholastic pursuit. It is purely entertainment. I watch them because I enjoy them. Learning is incidental and not the objective. I like to queue up playlists of documentaries and let them play through. The 'net has been excellent at facilitating this.
- ansible 9y ago
  An engine-out situation does get interesting though when the aircraft is low and slow, such as when taking off and landing. That's where good training is needed to recover quickly and successfully.
- jasode 9y ago
  What amazes me more is that the newest twinjets are now considered reliable enough to fly six hours away from the nearest landing strip Yes, there's also a short video about that: https://www.youtube.com/watch?v=HSxSgbNQi-g https://www.youtube.com/watch?v=HSxSgbNQi-g It's very interesting since ETOPS[1] affected the financial bets that Boeing made on 787 (point-to-point) vs Airbus with the A380 (hub-and-spoke). [1] https://en.wikipedia.org/wiki/ETOPS https://en.wikipedia.org/wiki/ETOPS
- SmellTheGlove 9y ago
  I wasn't really commenting on adding engines - I know that concept has been around a long time. This wasn't just an engine going down, this was catastrophic failure, and my amazement is in that no other part of the aircraft was affected outside of that one engine. > There's no other part of the airplane behind the engines either, so nothing to be hit by debris. No, but there's a wing and the fuselage nearby. Again, I'm not an engineer, but I'm assuming that in this type of failure, the part of the engine that's spinning might want to come laterally (is that the right word?), and that seems like it could be trouble. I'm amazed that it didn't. > What amazes me more is that the newest twinjets are now considered reliable enough to fly six hours away from the nearest landing strip -- that's how far they can coast on the single remaining engine if necessary! Totally amazing. I'm not sure, but is that only the A350XWB for now, or have others been certified past ETOPS-360? It's basically certified to the design limit of the aircraft, so I'm not sure what else has been designed for that. Even 5+ hours is nuts though. Somewhat related, but check out the Chilean regs on flying from the mainland to IPC/PPT. As far as I know, they still have the one aircraft rule.
- rphlx 9y ago
  The real concern here is not loss of thrust, but rather, what other parts of the airframe are seriously damaged or destroyed by the debris. In the accident record I believe there is precedent for separated engine parts seriously damaging wing and tail surfaces, causing at least partial loss of control.
ajarmst 9y ago
Agreed. When I saw the amount of damage, but little on the wing edge (there may be damage on the underside), I assumed the engine maintained confinement long enough to dissipate a lot of energy. If the cowl was damaged during this, then it may have then come off due to aerodymic stress. Either that or they were very lucky. From the photo I saw, it looks like they lost the forward cowl, fan and maybe a compressor stage. If I had to guess, failure of the low-pressure shaft.
- WalterBright 9y ago
  > I assumed the engine maintained confinement long enough to dissipate a lot of energy. Not unless the cowling was armored, which it wasn't at least back in the 80's. That thin sheet of aluminum won't even be noticed by the high strength fan spinning at tremendous speeds.
  - InternetOfStuff 9y ago
    > Not unless the cowling was armored, which it wasn't at least back in the 80's. AFAIK part of engine qualification is proving that the nacelle will retain a fan blade breaking off at full throttle. There are remarkable youtube videos of these qualification tests. The entire fan is another matter though. I assume the nacelle will offer some resistance, but not contain it entirely. And the turbines as well, they don't even attempt to retain those.
    - WalterBright 9y ago
      > qualification tests When did that become a requirement? > And the turbines as well, they don't even attempt to retain those. I knew about the turbine blades, I just assumed the fan blades were as uncontainable. I think my information is out of date. Thanks for the correction.
      - WalterBright 9y ago
        I found it: http://federal.elaws.us/cfr/title14.part33.section33.94 http://federal.elaws.us/cfr/title14.part33.section33.94 Looks like it became a requirement in 1984, after I left Boeing. So that's why I didn't know about it.
candiodari 9y ago
The thing about it is, that these sorts of things get designed because of evolution. Some engine fails in some way, and it gets redesigned. Planes fail, ditto. And after >100 years of that, we have pretty safe planes. What most amazes me is that despite the scientific knowledge we "have", we can't design a new engine from first principles directly. We do it through trial and error. Lots of hilarious/horrible error.
- KGIII 9y ago
  It is kind of nest how they have progressed, as well. It is sometimes little things that make a big difference. It iterative process, I suppose. Rolls Royce prides themselves on hiring interns. The little cone piece in front of the jet engine had issues with icing up. This had plagued jet engines for years. They tried all sorts of ways to fix it, including complex methods of supplying heat. One of their interns just happened to hear about this problem and suggested they simply make it out of rubber. Sure enough, it worked and the problem with that pointy bit freezing was solved. I'm sure it has a formal name and that it is probably not pointy bit or little cone piece. I don't actually know anything about jet engines, I just watched a documentary about Rolls Royce's jet manufacturing. Anyhow, that wasn't something that could probably have been designed with first principles. Someone, pretty much in passing, pretty much had to have that creative spark at just the right time and with just the right information. It's things like that story that make me think humans are going to be in the loop for a long time still and that AI taking over the world is still a long ways away.
  - perilunar 9y ago
    >I'm sure it has a formal name Spinner.
  - kortex 9y ago
    > It's things like that story that make me think humans are going to be in the loop for a long time still and that AI taking over the world is still a long ways away. I've found that the world continues to turn contingent on tremendous amount of what I call "dark wisdom" - crucial pieces of knowledge not found in any server, spec sheet, or manual. Usually inside the noggin of one or a few people. It just seems like a consequence of maintaining complex systems. In order for AI to fully take over, it would have to control and account for every corner case of every system, from mining the ore, to fabbing chips, to replacing wires chewed by rodents.
yread 9y ago
There was also this much discussed incident http://avherald.com/h?article=46a8f70a http://avherald.com/h?article=46a8f70a where they just shut one engine down above canada and continued on 3 accross the atlantic to kuwait (they couldn't safely - with enough fuel reserve for multiple approaches and a diversion - reach dubai)
anthonys 9y ago
I am fairly sure this was a contained failure. The reports I saw (unofficial) said no blades detached or hit the aircraft.

CydeWeys 9y ago

The A380 has four engines in total, and can easily tolerate the loss of just one in normal flight. Adding more engines has been a basic way to increase reliability since the beginning of the field; it's not just modern aircraft engineering. There's no other part of the airplane behind the engines either, so nothing to be hit by debris. What amazes me more is that the newest twinjets are now considered reliable enough to fly six hours away from the nearest landing strip -- that's how far they can coast on the single remaining engine if necessary!

inamberclad 9y ago
It's not really coasting. A transport category aircraft is required to have enough power to continue climbing if it loses an engine, so it must also have enough power to maintain level flight indefinitely (barring fuel consumption, oil leaks, or mechanical damage from an engine failure)
- CydeWeys 9y ago
  I meant to say "cruise", if that makes more sense.
  - KGIII 9y ago
    If it is any consolation, I knew what you meant. Otherwise, you'd probably have said something like glide and the glide ratio of the big planes isn't very good. Out of curiosity, I just checked for the A380 and the best guess is 15:1, so it does glide better than I expected, but still not that far. Google tells me that it'd glide ~130 miles if it had a starting altitude of 45,000'. That's better than I expected.
    - katastic 9y ago
      According to this: https://en.wikipedia.org/wiki/Gliding_flight#Aircraft_.28.22gliders.22.29 https://en.wikipedia.org/wiki/Gliding_flight#Aircraft_.28.22... The 747-200 also has a glide ratio of 15:1. I can't tell if that's amazing, good, or average. A sailplane can have up to 60:1! That's pretty impressive! According to this: A "clean A320" has 17:1. Neat. https://aviation.stackexchange.com/questions/14814/could-a-commercial-plane-like-airbus-a320-glide-with-no-working-engines-from-110 https://aviation.stackexchange.com/questions/14814/could-a-c... Something I never knew was this: >As someone said above, you have to remember, pretty well all descents are done with the thrust at idle. So I imagine the glide ratio is pretty important for all-purposes of flight and not just when engines go out.
      - KGIII 9y ago
        You descend at just about the stall speed. It's pretty close to the slowest the individual plane can go before losing lift. I believe the term for coming in with no lift, purely gliding, is called dead stick. A Cessna 172 is worse, for comparison. I believe they are just 9:1. I guess it improves if you stop the prop entirely. I assume it is less drag.
        tyw 9y ago
        best glide (converting altitude into the maximum distance) speed is quite a bit higher than the stall speed and found at the lift/drag max. minimum sink (converting altitude into the maximum time) is usually found about halfway between best glide speed and stall speed. http://learntoflylv.com/drag%20curve.gif http://learntoflylv.com/drag%20curve.gif
- dominotw 9y ago
  >A transport category aircraft is required to have enough power to continue climbing Can a plane takeoff with just one engine ?
  - hlandau 9y ago
    Yes. Twinjet airliners must be able to take off if one engine fails at or after V1.
    - FabHK 9y ago
      Which, incidentally, means that twins are quite powerful - a twin has 100% more engines (thus, power available) at takeoff than needed, while a quad has 33% more. Thus a twin has 50% more power than a similar 4 engine. At least conceptually-ish.
timb07 9y ago
Actually, adding engines increases resilience, or the ability to tolerate failure. The extra complexity of extra engines actually reduces reliability, since there are more components that can fail.
- FabHK 9y ago
  As the saying goes: If you have an engine failure in a twin, the remaining engine has enough power to take you to the scene of the accident.
WalterBright 9y ago
> There's no other part of the airplane behind the engines either, so nothing to be hit by debris. The fans spin very fast, and will fly out radially, not just fall back. They'll slice right through anything they contact. The Airbus flight was very, very lucky.
- cialowicz 9y ago
  The engines are designed so that a detached fan blade stays contained within the cowling. Here's a video of a fan blade containment test on a Rolls Royce Trent 500: https://youtu.be/RIOWjhjC1jM https://youtu.be/RIOWjhjC1jM
  - KGIII 9y ago
    I guess they use really, really precise timing and explosives to knock one blade loose in order to do the containment tests. They want it to come loose at a specific point in the revolution. The documentary didn't say why they wanted it to be at such a specific place, only that they did. I've long since forgotten the margin of error, but it was very small. You probably noticed that the individual blade is painted a different color and is different colors. My recollection is that they use the multiple colors because they do very high definition recording and the colors are all in different areas of the spectrum, so they can observe it better as the thing tends to be quickly obscured by fire and smoke. I probably do watch too many documentaries.
    - dba7dba 9y ago
      > I probably do watch too many documentaries. You are not alone. I actually watch more and more documentaries than movies or TV series. Reality is even stranger than fiction often.
      - KGIII 9y ago
        It has been great to see the proliferation of documentaries on the web. Streaming services have been a great thing for me. I watch documentaries pretty much to the exclusion of all other genres, except American football. Even if I'm not actively paying attention, I'll frequently have a documentary playing in the background. It's not a scholastic pursuit. It is purely entertainment. I watch them because I enjoy them. Learning is incidental and not the objective. I like to queue up playlists of documentaries and let them play through. The 'net has been excellent at facilitating this.
ansible 9y ago
An engine-out situation does get interesting though when the aircraft is low and slow, such as when taking off and landing. That's where good training is needed to recover quickly and successfully.
jasode 9y ago
What amazes me more is that the newest twinjets are now considered reliable enough to fly six hours away from the nearest landing strip Yes, there's also a short video about that: https://www.youtube.com/watch?v=HSxSgbNQi-g https://www.youtube.com/watch?v=HSxSgbNQi-g It's very interesting since ETOPS[1] affected the financial bets that Boeing made on 787 (point-to-point) vs Airbus with the A380 (hub-and-spoke). [1] https://en.wikipedia.org/wiki/ETOPS https://en.wikipedia.org/wiki/ETOPS
SmellTheGlove 9y ago
I wasn't really commenting on adding engines - I know that concept has been around a long time. This wasn't just an engine going down, this was catastrophic failure, and my amazement is in that no other part of the aircraft was affected outside of that one engine. > There's no other part of the airplane behind the engines either, so nothing to be hit by debris. No, but there's a wing and the fuselage nearby. Again, I'm not an engineer, but I'm assuming that in this type of failure, the part of the engine that's spinning might want to come laterally (is that the right word?), and that seems like it could be trouble. I'm amazed that it didn't. > What amazes me more is that the newest twinjets are now considered reliable enough to fly six hours away from the nearest landing strip -- that's how far they can coast on the single remaining engine if necessary! Totally amazing. I'm not sure, but is that only the A350XWB for now, or have others been certified past ETOPS-360? It's basically certified to the design limit of the aircraft, so I'm not sure what else has been designed for that. Even 5+ hours is nuts though. Somewhat related, but check out the Chilean regs on flying from the mainland to IPC/PPT. As far as I know, they still have the one aircraft rule.
rphlx 9y ago
The real concern here is not loss of thrust, but rather, what other parts of the airframe are seriously damaged or destroyed by the debris. In the accident record I believe there is precedent for separated engine parts seriously damaging wing and tail surfaces, causing at least partial loss of control.

ajarmst 9y ago

Agreed. When I saw the amount of damage, but little on the wing edge (there may be damage on the underside), I assumed the engine maintained confinement long enough to dissipate a lot of energy. If the cowl was damaged during this, then it may have then come off due to aerodymic stress. Either that or they were very lucky. From the photo I saw, it looks like they lost the forward cowl, fan and maybe a compressor stage. If I had to guess, failure of the low-pressure shaft.

WalterBright 9y ago
> I assumed the engine maintained confinement long enough to dissipate a lot of energy. Not unless the cowling was armored, which it wasn't at least back in the 80's. That thin sheet of aluminum won't even be noticed by the high strength fan spinning at tremendous speeds.
- InternetOfStuff 9y ago
  > Not unless the cowling was armored, which it wasn't at least back in the 80's. AFAIK part of engine qualification is proving that the nacelle will retain a fan blade breaking off at full throttle. There are remarkable youtube videos of these qualification tests. The entire fan is another matter though. I assume the nacelle will offer some resistance, but not contain it entirely. And the turbines as well, they don't even attempt to retain those.
  - WalterBright 9y ago
    > qualification tests When did that become a requirement? > And the turbines as well, they don't even attempt to retain those. I knew about the turbine blades, I just assumed the fan blades were as uncontainable. I think my information is out of date. Thanks for the correction.
    - WalterBright 9y ago
      I found it: http://federal.elaws.us/cfr/title14.part33.section33.94 http://federal.elaws.us/cfr/title14.part33.section33.94 Looks like it became a requirement in 1984, after I left Boeing. So that's why I didn't know about it.

candiodari 9y ago

The thing about it is, that these sorts of things get designed because of evolution. Some engine fails in some way, and it gets redesigned. Planes fail, ditto. And after >100 years of that, we have pretty safe planes. What most amazes me is that despite the scientific knowledge we "have", we can't design a new engine from first principles directly. We do it through trial and error. Lots of hilarious/horrible error.

KGIII 9y ago
It is kind of nest how they have progressed, as well. It is sometimes little things that make a big difference. It iterative process, I suppose. Rolls Royce prides themselves on hiring interns. The little cone piece in front of the jet engine had issues with icing up. This had plagued jet engines for years. They tried all sorts of ways to fix it, including complex methods of supplying heat. One of their interns just happened to hear about this problem and suggested they simply make it out of rubber. Sure enough, it worked and the problem with that pointy bit freezing was solved. I'm sure it has a formal name and that it is probably not pointy bit or little cone piece. I don't actually know anything about jet engines, I just watched a documentary about Rolls Royce's jet manufacturing. Anyhow, that wasn't something that could probably have been designed with first principles. Someone, pretty much in passing, pretty much had to have that creative spark at just the right time and with just the right information. It's things like that story that make me think humans are going to be in the loop for a long time still and that AI taking over the world is still a long ways away.
- perilunar 9y ago
  >I'm sure it has a formal name Spinner.
- kortex 9y ago
  > It's things like that story that make me think humans are going to be in the loop for a long time still and that AI taking over the world is still a long ways away. I've found that the world continues to turn contingent on tremendous amount of what I call "dark wisdom" - crucial pieces of knowledge not found in any server, spec sheet, or manual. Usually inside the noggin of one or a few people. It just seems like a consequence of maintaining complex systems. In order for AI to fully take over, it would have to control and account for every corner case of every system, from mining the ore, to fabbing chips, to replacing wires chewed by rodents.

yread 9y ago

There was also this much discussed incident http://avherald.com/h?article=46a8f70a http://avherald.com/h?article=46a8f70a where they just shut one engine down above canada and continued on 3 accross the atlantic to kuwait (they couldn't safely - with enough fuel reserve for multiple approaches and a diversion - reach dubai)

anthonys 9y ago

I am fairly sure this was a contained failure. The reports I saw (unofficial) said no blades detached or hit the aircraft.