4 ms·

Oh woah, very insightful discussion thread you found there. So the tl'dr is: the leading very preliminary theory is that the MD-11's left engine fell off the w

by mrb 11mo ago

Oh woah, very insightful discussion thread you found there. So the tl'dr is: the leading very preliminary theory is that the MD-11's left engine fell off the wing just like https://en.wikipedia.org/wiki/American_Airlines_Flight_191 https://en.wikipedia.org/wiki/American_Airlines_Flight_191 (a DC-10, the immediate predecessor of the MD-11) which was caused by maintenance errors weakening the pylon structure holding the engine.

rob74 11mo ago
This video from an aviation youtuber contains a picture of the engine: https://www.youtube.com/watch?v=U4q2ORhIQQc&t=526s https://www.youtube.com/watch?v=U4q2ORhIQQc&t=526s (the video itself is also worth watching in full IMHO). What strikes me as odd is that this looks like the "naked" engine, without the cowling/nacelle that usually surrounds it? Anyway, if an engine departs the aircraft shortly after (last-minute) maintenance was performed on it, that's indeed suspicious...
- actionfromafar 11mo ago
  The cowling was probably easily torn off when the engine went full speed like a missile for a few seconds after detaching.
- colechristensen 11mo ago
  The cowling isn't particularly structural so if your engine falls off on takeoff it's not so surprising that the cover didn't land with it.
- buildsjets 11mo ago
  The fan cowl and thrust reverser cowl are structurally fastened to the pylon/strut at the top, they only wrap around the engine, and are fastened to themselves at the bottom using latches. The strut considered part of the airframe structure. The inlet cowl is bolted directly to the engine, I saw in a picture that it was found approximately mid-field on the airport property.
stevenjgarner 11mo ago
The parallels with AA Flight 191 are striking. In THAT accident it was found [1]: 1) improper maintenance—American Airlines had used a forklift shortcut to remove the engine and pylon together, rather than following McDonnell Douglas’s prescribed method 2) The detachment tore away part of the wing’s leading edge, rupturing hydraulic lines and severing electrical power to key systems, including the slat-position indicator and stall warning (stick shaker). 3) The pilots followed the standard engine-out procedure and reduced airspeed to V₂, which caused the aircraft to stall and roll uncontrollably left. This procedure was later found out to be incorrect. Defective maintenance practices, inadequate oversight, vulnerabilities in DC-10 design, and unsafe training procedures combined to cause the crash, killing all 273 people on board and leading to sweeping reforms in airline maintenance and certification standards. [1] https://www.youtube.com/watch?v=F6iU7Mmf330 https://www.youtube.com/watch?v=F6iU7Mmf330
- akerl_ 11mo ago
  (asked earnestly out of lack of familiarity with this field) Are maintenance/certification standards distinct between passenger and cargo carriers? It's hard for me to tell if this suggests a step backwards in application of the reforms instigated after AA191 or that those reforms were never copied over to cargo aviation.
  - noer 11mo ago
    Yes but mostly related to purpose specific things: passenger carriers have additional safety checks for cabin things like seats, oxygen and evacuation systems. Cargo carriers have additional safety checks for things like cargo restraint and decompression systems. Furthermore (and I don't know if this is related to the cause of this crash), cargo jets tend to be older/refurbished passenger planes that have outlived their useful lives flying passengers.
    - cjrp 11mo ago
      > cargo jets tend to be older/refurbished passenger planes that have outlived their useful lives flying passengers. Exactly what happened in this case; the airplane was built in 1991 to carry passengers, and then converted in 2006 for freight. https://www.planespotters.net/airframe/mcdonnell-douglas-md-11-n259up-united-parcel-service-ups/rmnno3 https://www.planespotters.net/airframe/mcdonnell-douglas-md-...
bluebarbet 11mo ago
From all the annals of aviation disaster, flight 191 is possibly the one that haunts my nightmares the worst. Perhaps because the scenario feels plausible for every single take-off. Perhaps just because of the famous photo.

by mrb 11mo ago

rob74 11mo ago

This video from an aviation youtuber contains a picture of the engine: https://www.youtube.com/watch?v=U4q2ORhIQQc&t=526s https://www.youtube.com/watch?v=U4q2ORhIQQc&t=526s (the video itself is also worth watching in full IMHO). What strikes me as odd is that this looks like the "naked" engine, without the cowling/nacelle that usually surrounds it? Anyway, if an engine departs the aircraft shortly after (last-minute) maintenance was performed on it, that's indeed suspicious...

actionfromafar 11mo ago
The cowling was probably easily torn off when the engine went full speed like a missile for a few seconds after detaching.
colechristensen 11mo ago
The cowling isn't particularly structural so if your engine falls off on takeoff it's not so surprising that the cover didn't land with it.
buildsjets 11mo ago
The fan cowl and thrust reverser cowl are structurally fastened to the pylon/strut at the top, they only wrap around the engine, and are fastened to themselves at the bottom using latches. The strut considered part of the airframe structure. The inlet cowl is bolted directly to the engine, I saw in a picture that it was found approximately mid-field on the airport property.

stevenjgarner 11mo ago

The parallels with AA Flight 191 are striking. In THAT accident it was found [1]: 1) improper maintenance—American Airlines had used a forklift shortcut to remove the engine and pylon together, rather than following McDonnell Douglas’s prescribed method 2) The detachment tore away part of the wing’s leading edge, rupturing hydraulic lines and severing electrical power to key systems, including the slat-position indicator and stall warning (stick shaker). 3) The pilots followed the standard engine-out procedure and reduced airspeed to V₂, which caused the aircraft to stall and roll uncontrollably left. This procedure was later found out to be incorrect. Defective maintenance practices, inadequate oversight, vulnerabilities in DC-10 design, and unsafe training procedures combined to cause the crash, killing all 273 people on board and leading to sweeping reforms in airline maintenance and certification standards. [1] https://www.youtube.com/watch?v=F6iU7Mmf330 https://www.youtube.com/watch?v=F6iU7Mmf330

akerl_ 11mo ago
(asked earnestly out of lack of familiarity with this field) Are maintenance/certification standards distinct between passenger and cargo carriers? It's hard for me to tell if this suggests a step backwards in application of the reforms instigated after AA191 or that those reforms were never copied over to cargo aviation.
- noer 11mo ago
  Yes but mostly related to purpose specific things: passenger carriers have additional safety checks for cabin things like seats, oxygen and evacuation systems. Cargo carriers have additional safety checks for things like cargo restraint and decompression systems. Furthermore (and I don't know if this is related to the cause of this crash), cargo jets tend to be older/refurbished passenger planes that have outlived their useful lives flying passengers.
  - cjrp 11mo ago
    > cargo jets tend to be older/refurbished passenger planes that have outlived their useful lives flying passengers. Exactly what happened in this case; the airplane was built in 1991 to carry passengers, and then converted in 2006 for freight. https://www.planespotters.net/airframe/mcdonnell-douglas-md-11-n259up-united-parcel-service-ups/rmnno3 https://www.planespotters.net/airframe/mcdonnell-douglas-md-...

bluebarbet 11mo ago

From all the annals of aviation disaster, flight 191 is possibly the one that haunts my nightmares the worst. Perhaps because the scenario feels plausible for every single take-off. Perhaps just because of the famous photo.