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AF66 CDG-LAX diverts - uncontained engine failure over Atlantic

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AF66 CDG-LAX diverts - uncontained engine failure over Atlantic

Old 30th Sep 2017, 23:45
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Was this a fan disk failure, or an LP shaft failure? If the shaft went ping, the fan would hurtle out the front (taking who knows what with it), and the LP turbine would come out the back pretty quickly too.
GE/Pratt design practice is that if the LP shaft breaks, it'll move aft enough that the turbine blades will clash with the turbine nozzles in a controlled manner to bring the shaft to a stop. Otherwise the unloaded LP shaft will quickly overspeed (Rolls had issues with this on the RB211 about 35 years ago - cut the back off a 747 engine when the LP turbine came apart).


The issue with the GEnx fan shaft was related to use of the wrong anti-seize compound during assembly of the fan shaft - this caused stress corrosion which then failed the shaft.
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Old 1st Oct 2017, 00:05
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Originally Posted by tdracer
GE/Pratt design practice is that if the LP shaft breaks, it'll move aft enough that the turbine blades will clash with the turbine nozzles in a controlled manner to bring the shaft to a stop.
With the curvic coupling still in place, the LP shaft is still in it's normal position. I doubt the shaft has moved back.

The ring has left the scene though, I suspect with it's blades still attached ... there seems to be little damage to the bypass guide vanes, just the fracture around the blade retainer ring transition cone ... there is little impact damage on the containment ring, and the inlet to the LP compressor looks in good shape too .. all pointing to the fan assembly leaving the scene in one piece.
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Old 1st Oct 2017, 00:26
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Originally Posted by b1lanc
Be interesting to see what they do with the 380.
At a guess, change the engine and fly it out.....
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Old 1st Oct 2017, 00:43
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A 737 is being sent from Mirabel, presumably the other half of the rescue pair

http://flightaware.com/live/flight/NRL58/history/20171001/0100Z/CYMX/CYYR
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Old 1st Oct 2017, 00:52
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So, will hull insurance cover the costs in this case??
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Old 1st Oct 2017, 00:52
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With the curvic coupling still in place, the LP shaft is still in it's normal position. I doubt the shaft has moved back.
The distance we are talking about is only a few millimeters - I don't think the picture is good enough to make that determination.
You WANT the shaft to move and the blades to clash - suddenly unload the LP turbine by removing the fan and you quickly have a turbine running well above it's burst speed. Even if the N1 sensor is still working the FADEC can't pull back the fuel quick enough to prevent a massive uncontained turbine failure.

Last edited by tdracer; 1st Oct 2017 at 01:30. Reason: fixed typo
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Old 1st Oct 2017, 01:03
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I suspect that IF the LP shaft had NOT moved back But remained free wheeling, the photo would NOT be quite sharp as regards the blades being motionless in the x hundred mph airstream. At the same time, damage to the blades trailing edge may not be apparant in the photo.

It is amazing ( lucky ? ) that the forward engine mount seems to be intact and that no or few punctures of the wing and fuselage seem to be evident ( no fuel leaks claimed by ground inspection ? )
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Old 1st Oct 2017, 01:10
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Looks like F-GZNO is the 777 that will be sent to Goose . It landed in YUL at 8pm from CDG
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Old 1st Oct 2017, 01:28
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Originally Posted by andy_smith89uk
PAX video:
Airbus horror as footage shows plane engine disintegrate mid-flight from Paris to Los Angeles - Bristol Post

From the Bristol Post: "Videos and pictures posted on social media by horrified travellers show a large section of the back of the engine is missing from the Air France flight..."

"back of the engine is missing"

Holy crap. The stupid never ceases to amaze. Now back to non-pilot lurk mode.
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Old 1st Oct 2017, 01:46
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Last edited by Bleve; 1st Oct 2017 at 02:04.
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Old 1st Oct 2017, 02:10
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Originally Posted by Airbubba
Listening to the tower recording, parts were falling off the plane as it rolled to a stop. The fire crew ('Red Leader') was hesitant to approach the aircraft with two engines still turning to retrieve the FOD for further taxi. I'm guessing Goose doesn't have an A380 towbar.

Number one didn't go into reverse on landing.

Time to lease a Volga-Dnepr An-124 into YYR?

I'm sure the attorneys in first class are passing out business cards to the hoi polloi.
Engines 1 & 4 on the A380 don't have reverse thrust capability as they hang so far off the centreline there's a risk of throwing up foreign objects.
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Old 1st Oct 2017, 03:01
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How old is the plane?

Who will lead and who else will participate in the investigation?
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Old 1st Oct 2017, 03:09
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How old is the plane?
The relevant question is not the aircraft, it's hours and cycles on the event engine - both since new and since overhaul (if appropriate).
I don't recall how Pratt and GE split the responsibilities on the GP7000 - who did the LP section?
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Old 1st Oct 2017, 04:09
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They should find the near complete fan neatly wrapped in many layers of ballistic Kevlar. Should be easy to spot from the air if it fell on land.
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Old 1st Oct 2017, 04:23
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Just thinking out loud here, but on the GEnx, the fan is a 'module' - something that can be removed/replaced almost like an LRU.
If the GP7000 is similar, might there have been a recent fan module replacement what wasn't performed correctly (or perhaps not completely)?
That might explain what otherwise seems a rather baffling failure...
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Old 1st Oct 2017, 04:59
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Conso those blades in the picture do not rotate, basically fan exit Guide vanes & Compressor stator stage.
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Old 1st Oct 2017, 05:26
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I would love to hear the cockpit CVR, I’m sure it would make a good training tool. Sitting there quiet quietly in cruise when suddenly all hell breaks loose. I wonder how many ECAM alerts they had in total, I recall the Quantas crew being somewhat overwhelmed by them.

Relieved that everyone landed safely and has a story to tell their grandkids. Hopefully there is no reason to ground aircraft with the same engine.
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Old 1st Oct 2017, 05:37
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Originally Posted by Airbubba
Listening to the tower recording, parts were falling off the plane as it rolled to a stop. The fire crew ('Red Leader') was hesitant to approach the aircraft with two engines still turning to retrieve the FOD for further taxi. I'm guessing Goose doesn't have an A380 towbar.

Number one didn't go into reverse on landing.

Time to lease a Volga-Dnepr An-124 into YYR?

I'm sure the attorneys in first class are passing out business cards to the hoi polloi.

Number four didn’t go into reverse either
no reverse is fitted on the A380 outboard
engines
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Old 1st Oct 2017, 05:48
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Actually this incident is quite similar to this one:
Accident: Southwest B737 near Pensacola on Aug 27th 2016, uncontained engine failure
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Old 1st Oct 2017, 06:04
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Ah, actually it's not. The Southwest event lost the inlet - the fan (well, most of it) was still there. As I understand, a fan blade fractured and the resultant vibration caused the inlet to fail and depart the aircraft.
I don't recall an engine losing the entire fan assembly since a couple RB211 events back in the 1970s (IIRC the fan shaft broke due to a bearing fire that overheated the shaft).

Last edited by tdracer; 1st Oct 2017 at 08:01.
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