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And now the Boeing 777...

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langwadt:

--- Quote from: ve7xen on February 24, 2021, 07:43:17 pm ---
--- Quote from: coppercone2 on February 24, 2021, 06:55:24 am ---how does it stay burning at 600mph? it must be either very flammable, very hot or pilot lighted by something

is the engine like still sustaining itself by oil dripping into the middle and igniting and the flame being pushed out to make it look like its on fire on the outside despite the outside not burning? i.e. combustion occurs in the same place as it does with the fuel but instead occurs with residual oils but the amount of fire is excessive so it gets pushed out, operating kinda like a reflux condenser, in terms of liquid being sucked into the middle then fire being pushed out, not in the sense of condensation?

--- End quote ---

The aircraft isn't travelling at 600mph, nor is its indicated airspeed (which would represent how much the fire 'feels' the air) 600mph. They would've been at an IAS of about 280kts or 322mph. Ground speed would have been somewhat higher, maybe 320kts. They were fairly low in the climb, not at altitude in cruise.

Where you see the fire emanating from is the thrust reverser 'translating sleeve' with many vanes to redirect the air to the rear. The thrust reverser doors appear to be closed, so no significant airflow from the fan duct (or fuel or anything else from the engine core) can reach this area in this configuration. Since the purpose of these vanes is to direct air rearward, the pockets are 'out of the wind' so to speak, and yeah maybe there is an element of negative pressure helping to suck fuel from whatever the fuel source is. From the reports so far, it doesn't sound like there were any major fuel leaks and the fuel shutoffs worked as designed, so I'd guess this is either residual fuel from ruptured lines or hydraulic oil, possibly from the TR mechanism itself, but could be anything mounted on the outside of the engine. This will be a focus of the investigation for sure.

It's definitely not that you're seeing combustion in the core, the TR doors are closed, and even if they were open, you'd only see inside the fan duct, not the core. Any flame you might observe (extremely unlikely) inside the combustion chambers due to catastrophic damage would be much deeper inside the engine than is observed here which is clearly near the surface. If that were happening, you'd probably see it inside the fan duct as well from the front/rear.

Thrust from this would be negligible, it's clearly not a very significant amount of fire, and it's happening in 'free air'.

--- End quote ---

afaiu the thrust reverser part that is on fire is made of carbonfiber

drussell:
Further information today regarding this series of engines on 777s from Blancolirio, a trustworthy source...


james_s:
It's obviously not Boeing's fault, but it still reflects badly on them simply because most people don't understand that Boeing doesn't build the engines.

On the other hand, engine failure was mostly contained and the plane landed safely with nobody hurt. That's close to the best possible outcome of something like this.

coppercone2:
isent it up to boeing to analyze the engine to make sure its good? They vet the subassembly after all. It will be complicated to figure out whos fault it is

i.e.
lack of maintenance
incorrect maintenance
bad from factory
1) design flaw
2) manufacturing defect (QC fail)
installed incorrectly/damaged during installation
system interfaced incorrectly (the engine has I/O), or its just not compatible with the design for whatever mechanical reason, if its not related to hydraulics or electronics or telemetry
failed to inspect device before/after installation
failed to perform more stringent tests
control safety system fail (did not monitor telemetry or handwaving was involved)

of course its up to the investigators to find out what happened

drussell:

--- Quote from: coppercone2 on February 27, 2021, 05:48:17 am ---isent it up to boeing to analyze the engine to make sure its good? They vet the subassembly after all. It will be complicated to figure out whos fault it is
--- End quote ---

No, the special sonic + thermal imaging tests are only performed at Pratt & Whitney's manufacturing facility when fan blade inspections are required,


--- Quote ---i.e.
lack of maintenance
incorrect maintenance
bad from factory
1) design flaw
2) manufacturing defect (QC fail)
installed incorrectly/damaged during installation
system interfaced incorrectly (the engine has I/O), or its just not compatible with the design for whatever mechanical reason, if its not related to hydraulics or electronics or telemetry
failed to inspect device before/after installation
failed to perform more stringent tests
control safety system fail (did not monitor telemetry or handwaving was involved)

of course its up to the investigators to find out what happened
--- End quote ---

Did you watch the video?  The tests are explained in there.  It is quite possibly the same issues as the UAL flight 1175 blade failure, which was basically improper testing during inspection due to multiple factors at Pratt & Whitney.

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