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The A380 has two hydraulic systems. If the priamry fails, the aircraft is still fully flyable. Some extra things like slats don't work anymore but those aren't

The A380 has two hydraulic systems. If the priamry fails, the aircraft is still fully flyable. Some extra things like slats don't work anymore but those aren't critical for flight and landing. If the secondary hydraulics fail, there are still extra electric actuators to move the control surfaces. Source: http://www.roger-wilco.net/wp-content/uploads/2010/11/Untitled-110.jpg http://www.roger-wilco.net/wp-content/uploads/2010/11/Untitl...

revelation 9y ago
I mean, primary and backup hydraulics are hopelessly intertwined on this systems diagram, certainly physically. Not sure how much that is going to help against parts flying into it. Which is of course what happened in that linked incident below: https://en.wikipedia.org/wiki/United_Airlines_Flight_232 https://en.wikipedia.org/wiki/United_Airlines_Flight_232 The three hydraulic systems were separate, so that failure of any one of them would leave the crew with full control, but lines for all three systems shared the same narrow passage through the tail where the engine debris had penetrated, and thus control surfaces were inoperative.
- anarazel 9y ago
  IIRC there's valves to contain such failures at regular intervals. And the electrical backup system can then provide some power in the cutoff sections. I'd hope that airplane designers learned a thing or two since the DC-10 (and have some additional tools to play with).
  - WalterBright 9y ago
    They do learn from every accident. It's why every accident is thoroughly investigated and the causes determined as well as possible.
- eesmith 9y ago
  As your reference points out: "Newer aircraft designs such as the McDonnell Douglas MD-11 have incorporated hydraulic fuses to isolate a punctured section and prevent a total loss of hydraulic fluid." A quick search for "A 380 hydraulic fuses" finds sources like http://www.airliners.net/forum/viewtopic.php?t=765509 http://www.airliners.net/forum/viewtopic.php?t=765509 : > If one or both hydraulic systems fail, the following hydro-electrical backups remain available: For flight controls: The Electrical-Hydrostatic Actuators (EHAs) and the Electrical Backup Hydraulic Actuators (EBHAs) For braking and steering: The Local Electro-Hydraulic Generation System (LEHGS)" That's depicted in the image bad_alloc showed. And, "hopelessly intertwined"? Is that your viewpoint as a software developer, or are you an aircraft designer? Because I'm sure that an outsider would see my code as "hopelessly intertwined" even when it isn't.
  - Grazester 9y ago
    "Because I'm sure that an outsider would see my code as "hopelessly intertwined" " That depends. Do you use the object oriented programming model? LOL
  - inferiorhuman 9y ago
    > And, "hopelessly intertwined"? Is that your viewpoint as a software developer, or are you an aircraft designer? Because I'm sure that an outsider would see my code as "hopelessly intertwined" even when it isn't. Even with modern aircraft, even with the A380, when a fan lets go or the engine grenades bad things happen. Qantas Flight 32, an A380, suffered a UCE and everyone was very lucky that there were additional, experienced pilots on board. Take a look at the ATSB report. Pretty much everything that could fail, did. Engine control for the #1 (IIRC) engine had been destroyed and it took the firefighters three hours to pump enough water to shut down the engine. Without the extra crew things could have gone very differently. British Airways 2276, a 777 -- a plane that has an excellent safety record, suffered a UCE and the plane caught fire. Luckily the pilots were able to abort the takeoff, but fire on a plane is about the worst possible failure mode. AA #383, a 767, also suffered a UCE on takeoff that resulted in a massive fire. Cameroon Airlines Flight 786, same deal. UCE, punctured fuel tank, fire. So, yes, things have almost certainly gotten better but given how much energy is released when a high bypass turbofan lets go, it's pretty damn hard to design something that's completely failsafe.
    - eesmith 9y ago
      Sure. But do all those correct statements mean that the A380 hydraulic control systems, and their backups, are "hopelessly intertwined" to an aircraft designer?
      - inferiorhuman 9y ago
        > Sure. But do all those correct statements mean that the A380 hydraulic control systems, and their backups, are "hopelessly intertwined" to an aircraft designer? I'd hope so, given that all the redundancy didn't prevent an engine control failure on the A380.

revelation 9y ago

I mean, primary and backup hydraulics are hopelessly intertwined on this systems diagram, certainly physically. Not sure how much that is going to help against parts flying into it. Which is of course what happened in that linked incident below: https://en.wikipedia.org/wiki/United_Airlines_Flight_232 https://en.wikipedia.org/wiki/United_Airlines_Flight_232 The three hydraulic systems were separate, so that failure of any one of them would leave the crew with full control, but lines for all three systems shared the same narrow passage through the tail where the engine debris had penetrated, and thus control surfaces were inoperative.

anarazel 9y ago
IIRC there's valves to contain such failures at regular intervals. And the electrical backup system can then provide some power in the cutoff sections. I'd hope that airplane designers learned a thing or two since the DC-10 (and have some additional tools to play with).
- WalterBright 9y ago
  They do learn from every accident. It's why every accident is thoroughly investigated and the causes determined as well as possible.
eesmith 9y ago
As your reference points out: "Newer aircraft designs such as the McDonnell Douglas MD-11 have incorporated hydraulic fuses to isolate a punctured section and prevent a total loss of hydraulic fluid." A quick search for "A 380 hydraulic fuses" finds sources like http://www.airliners.net/forum/viewtopic.php?t=765509 http://www.airliners.net/forum/viewtopic.php?t=765509 : > If one or both hydraulic systems fail, the following hydro-electrical backups remain available: For flight controls: The Electrical-Hydrostatic Actuators (EHAs) and the Electrical Backup Hydraulic Actuators (EBHAs) For braking and steering: The Local Electro-Hydraulic Generation System (LEHGS)" That's depicted in the image bad_alloc showed. And, "hopelessly intertwined"? Is that your viewpoint as a software developer, or are you an aircraft designer? Because I'm sure that an outsider would see my code as "hopelessly intertwined" even when it isn't.
- Grazester 9y ago
  "Because I'm sure that an outsider would see my code as "hopelessly intertwined" " That depends. Do you use the object oriented programming model? LOL
- inferiorhuman 9y ago
  > And, "hopelessly intertwined"? Is that your viewpoint as a software developer, or are you an aircraft designer? Because I'm sure that an outsider would see my code as "hopelessly intertwined" even when it isn't. Even with modern aircraft, even with the A380, when a fan lets go or the engine grenades bad things happen. Qantas Flight 32, an A380, suffered a UCE and everyone was very lucky that there were additional, experienced pilots on board. Take a look at the ATSB report. Pretty much everything that could fail, did. Engine control for the #1 (IIRC) engine had been destroyed and it took the firefighters three hours to pump enough water to shut down the engine. Without the extra crew things could have gone very differently. British Airways 2276, a 777 -- a plane that has an excellent safety record, suffered a UCE and the plane caught fire. Luckily the pilots were able to abort the takeoff, but fire on a plane is about the worst possible failure mode. AA #383, a 767, also suffered a UCE on takeoff that resulted in a massive fire. Cameroon Airlines Flight 786, same deal. UCE, punctured fuel tank, fire. So, yes, things have almost certainly gotten better but given how much energy is released when a high bypass turbofan lets go, it's pretty damn hard to design something that's completely failsafe.
  - eesmith 9y ago
    Sure. But do all those correct statements mean that the A380 hydraulic control systems, and their backups, are "hopelessly intertwined" to an aircraft designer?
    - inferiorhuman 9y ago
      > Sure. But do all those correct statements mean that the A380 hydraulic control systems, and their backups, are "hopelessly intertwined" to an aircraft designer? I'd hope so, given that all the redundancy didn't prevent an engine control failure on the A380.