5 ms·

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 e

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 I think my information is out of date.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.
      - InternetOfStuff 9y ago
        Thanks for taking the time to dig your way to the facts, and then report back with what you found. As it turns out, I learned something as well. Contrary to what I said, that same passage requires failing turbine blades to be retained as well. However, they seem to be drawing the line at complete fan or compressor assemblies or turbine disks.
- hueving 9y ago
  I suggest you watch the blade separation test videos. The entire point of the cowling is to contain fan blade loss.
  - WalterBright 9y ago
    The main purpose of the cowling is to improve the efficiency of the fan by preventing the air from being slung off radially. https://en.wikipedia.org/wiki/Ducted_fan https://en.wikipedia.org/wiki/Ducted_fan
    - ajarmst 9y ago
      Agreed, but failure containment is another of its purposes, at least on contemporary turbofan engines.
    - hueving 9y ago
      Did you ignore what I said and not watch the blade release tests?
  - boulos 9y ago
    Indeed. https://youtu.be/736O4Hz4Nk4 https://youtu.be/736O4Hz4Nk4 is a bit long, but they detonate some charges on a blade, watch it take out all the others and keep it all inside.

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.
    - InternetOfStuff 9y ago
      Thanks for taking the time to dig your way to the facts, and then report back with what you found. As it turns out, I learned something as well. Contrary to what I said, that same passage requires failing turbine blades to be retained as well. However, they seem to be drawing the line at complete fan or compressor assemblies or turbine disks.
hueving 9y ago
I suggest you watch the blade separation test videos. The entire point of the cowling is to contain fan blade loss.
- WalterBright 9y ago
  The main purpose of the cowling is to improve the efficiency of the fan by preventing the air from being slung off radially. https://en.wikipedia.org/wiki/Ducted_fan https://en.wikipedia.org/wiki/Ducted_fan
  - ajarmst 9y ago
    Agreed, but failure containment is another of its purposes, at least on contemporary turbofan engines.
  - hueving 9y ago
    Did you ignore what I said and not watch the blade release tests?
- boulos 9y ago
  Indeed. https://youtu.be/736O4Hz4Nk4 https://youtu.be/736O4Hz4Nk4 is a bit long, but they detonate some charges on a blade, watch it take out all the others and keep it all inside.