AF66 CDG-LAX diverts - uncontained engine failure over Atlantic
I believe I am correct that the Engine Alliance GP7000 has ceased production. Emirates switched to the Rolls-Royce engine a couple of years ago, and the remaining operators of this engine option have had all aircraft delivered.
I suspect with no hangar facilities at Goose Bay, a temporary Canvas Tent will be used to cover the engineering works required to swop the engines.
However with winter fast approaching, they may be delayed until next year if heavy snow falls and damages their tent.
Maybe they could just fly it as it is... It's flown like that before, and there is less drag without the fan.
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However with winter fast approaching, they may be delayed until next year if heavy snow falls and damages their tent.
Maybe they could just fly it as it is... It's flown like that before, and there is less drag without the fan.
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Airbus show a backlog of 101 A380 orders, which I believe still includes the 3 GP7270-powered examples that Air Accord were due to take on behalf of Transaero before the latter went bust.
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Aircraft engineers - How long would an inspection like this take on each aircraft?
Propulsor Advantage
Modeled after the successful GE90 program, the GP7200 fan module splits from the rest of the engine, allowing you to save money on spare engine costs.
Engine Alliance Service: 24/7 Parts & Support for GP7200
Modeled after the successful GE90 program, the GP7200 fan module splits from the rest of the engine, allowing you to save money on spare engine costs.
Engine Alliance Service: 24/7 Parts & Support for GP7200
How many spare fan modules available at each carrier? Spare engines to cannibalize parts from or simply change?
It will take some time and scrambling for the carrier's engineering departments to figure out the most efficient methods to accomplish the ASB/AD.
Although I'm uninvolved in this issue, I can say with some certainty that EA is quickly assembling the tools and kits of any consumables involved along with trained personnel that will go to the operators to assist in the needed inspections.
Interesting that we have an AD so early in the game - is this just a precautionary move or can we surmise that they found something significant examining the remains of the engine ?
BTW, 3527 cycles may be 'high cycles' for the GP7000, that's not even close to what I'd call a 'high cycle engine'. There are lots of PW4000s and CF6-80C2 engines out there that have several times that number of cycles (granted, having been overhauled multiple times). I'd be curious to know if (and when) the event engine was overhauled (3500 cycles on a long haul aircraft would work out to be something around 30,000 hours so I suspect it's been overhauled at least once, probably twice).
FAA orders Airbus A380 engine inspections - MarketWatch
some excerpts
" According to the FAA, the fan hub on a "relatively high cycle" engine suddenly failed, "
" The manufacturer said the checks take roughly two hours and can be done without removing engines from aircraft. "
My comments
Typical fatigue lives run to 20k cycles and that the comment above about relatively high cycles is significant
On the other hand without having access to fracture surfaces there is a possibility that a wear out mode might have crept in on specific engines. As just an example a wearout mode might affect vibratory stresses (exceedingly rare but have happened over the last 50 years).
To proceed with any airworthiness action one needs data. The quickest way to get this is to inspect a portion of the fleet for any gross cracking or abnormal fretting to joint surfaces. Eddy current comes to mind along with basic eyeballs. Then adjust follow on inspections accordingly
some excerpts
" According to the FAA, the fan hub on a "relatively high cycle" engine suddenly failed, "
" The manufacturer said the checks take roughly two hours and can be done without removing engines from aircraft. "
Typical fatigue lives run to 20k cycles and that the comment above about relatively high cycles is significant
On the other hand without having access to fracture surfaces there is a possibility that a wear out mode might have crept in on specific engines. As just an example a wearout mode might affect vibratory stresses (exceedingly rare but have happened over the last 50 years).
To proceed with any airworthiness action one needs data. The quickest way to get this is to inspect a portion of the fleet for any gross cracking or abnormal fretting to joint surfaces. Eddy current comes to mind along with basic eyeballs. Then adjust follow on inspections accordingly
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pax2908 linked an article in Maintenance and Engineering that states on page 92 (page 8 in the PDF): "According to IBA, GP7200-equipped A380s are operating at about 4,550 EFH and 500 EFC a year". The engine entered service in 2008, so the oldest engines are probably still below 5000 flight cycles? which would make 3500 high by comparison to the rest of the fleet, hence "relatively".
...I suspect initial inspections suggest the fan spool failed first - likely fatigue related - and they're requiring a once through the fleet inspection to make sure there isn't another engine out there about to fail. As the investigation progresses I'd expect additional ADs, either additional (or repetitive) inspections or actual design modifications.
There's quite a lot of continuous load on a fan spool - all that power, etc. I don't imagine that it takes very long for a very small crack to become a very large crack. What puzzles me is that if one supposes there was some pre-flight defect, it wasn't so severe as all that; it didn't result in failure at take-off (when there's maximum load on, well, everything).
But then it couldn't stand up to the subsequent cruise phase, where the loads ought to be substantially less? That doesn't make sense really. Crack growth in a part under continuous load is probably exponential. For this to stack up as a preflight defect, the take-off must have opened it up to the very edge of failure so that the less punishing cruise loads could finish it off. That seems remarkable.
So I suppose I'm questioning (from my position of utter non-involvement) exactly what it is they'd expect to see? A fan spool doesn't sound to me like a component that can afford to have a noticeable crack in it but somehow still hold together during the most stressful phase of it's flight cycle.
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2 hr Inspection?
How much can you find on a 2hr inspection, but a rather big surface crack?
I have no doubt EA already have a pretty good clue if this is a one off!
( Awol is you like) or a design weakness for better word. Or other issues.
As for it to depart in cruise, some choppy turbulence must put some stress on that big gyroscope.
Anyway, hope they find the rest of the fan and the likely cause!
Would be great to know the spectacular sequence of events.
For now I am quite happy to put put around with my 2 trusted and proven CFM 56s, dont much care for the fan racing me to destination.
I have no doubt EA already have a pretty good clue if this is a one off!
( Awol is you like) or a design weakness for better word. Or other issues.
As for it to depart in cruise, some choppy turbulence must put some stress on that big gyroscope.
Anyway, hope they find the rest of the fan and the likely cause!
Would be great to know the spectacular sequence of events.
For now I am quite happy to put put around with my 2 trusted and proven CFM 56s, dont much care for the fan racing me to destination.
no
Fed Ex had early orders but these were NTU
Fed Ex had early orders but these were NTU
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No. The a/c has not been registered in the States, and interestingly it does not presently have NGS installed, which would present problems ref SFAR88.
The EA SB involves removing the spinner sections and performing visual inspections of the fan disc, checking for mechanical damage in various areas. The inspection is performed with the fan blades in situ.
Whether this is just a precautionary measure will have to be judged when the remnants of the departed disc are recovered from the ice cap, presumably
The EA SB involves removing the spinner sections and performing visual inspections of the fan disc, checking for mechanical damage in various areas. The inspection is performed with the fan blades in situ.
Whether this is just a precautionary measure will have to be judged when the remnants of the departed disc are recovered from the ice cap, presumably
the order was for Engine Alliance GP7200-powered aircraft
UPS was also had a 380F order for 10 + 10 and ILFC for 5 and all those were lost too also GP7200 power
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Well as a long retired gas turbine engine designer with Rolls-Royce I can tell you that fatigue is the most likely cause of sudden failure in normal operation. The range of vibration frequencies and intensities which are available in an engine of this complexity are legion. In my time a lot of effort went into positioning pipe clips to avoid resonance of their attached pipes and that was just in the day of two spool engines. The same will apply to internal components and there is always the problem of a minor defect in a batch of material or a mistake in heat treatment which can seriously prejudice the integrity of some vital part.
The most extensive damage I ever saw during the testing of the Conway was when a tiny inclusion of slag in a stainless steel tube in the fuel cooled oil cooler allowed a slow addition of fuel to the oil. Eventually the centre bearing failed, the LP shaft overheated and twisted like toffee, and let the turbine go, and we collected bits of that item from all over the factory.
Hopefully there will be enough damaged parts found to establish what actually happened here, but I wouldn't be holding my breath.
Now I suggest that till more evidence appears all this speculation should cease.
The most extensive damage I ever saw during the testing of the Conway was when a tiny inclusion of slag in a stainless steel tube in the fuel cooled oil cooler allowed a slow addition of fuel to the oil. Eventually the centre bearing failed, the LP shaft overheated and twisted like toffee, and let the turbine go, and we collected bits of that item from all over the factory.
Hopefully there will be enough damaged parts found to establish what actually happened here, but I wouldn't be holding my breath.
Now I suggest that till more evidence appears all this speculation should cease.
Last edited by Olympia 463; 14th Oct 2017 at 13:43. Reason: typo
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Olympia - being an engine designer, you probably have the answer. Fatigue is induced by stress cycles. The largest cyclic change is likely to be between engine off and max power when the fan is turning the fastest providing the largest tangential load on the hub with the hub also needing to withstand most of the 70,000+ plus thrust load. I assume this is why they are concerned with cycles. As you point out there are vibration cycles at load that also contribute to fatigue and as this engine failed in cruise, are likely to be a significant contributor. Any inclusion during manufacturing creates a stress riser and ultimate failure initiator. I haven't even touched on thermal cycles. How do you manage to design for this? Is it by overdesign or by realization there will be a failure at some point, predict the safe limit, and replace the critical component at that point?
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NWA,
You are right to say that changes in load can have an effect on the progress of a fatigue crack. And you rightly note that the maximum axial load on the engine is at the front where the fan is since it is the part which is producing most of the thrust. I had a feeling these big fans which are really ducted propellors would have a big influence on the stresses at the front of the engine. That fan is literally dragging the whole aeroplane behind it. We had it easier on the low bypass engines like the Conway (0.6 bypass ratio). But what do I know - it is a long time since I designed the turbines and thrust reversers on the Conway and I left RR before the RB211 debacle. Stewart Miller the man who rescued RR from that catastrophe worked on the next board to me in those long gone days.
You are right to say that changes in load can have an effect on the progress of a fatigue crack. And you rightly note that the maximum axial load on the engine is at the front where the fan is since it is the part which is producing most of the thrust. I had a feeling these big fans which are really ducted propellors would have a big influence on the stresses at the front of the engine. That fan is literally dragging the whole aeroplane behind it. We had it easier on the low bypass engines like the Conway (0.6 bypass ratio). But what do I know - it is a long time since I designed the turbines and thrust reversers on the Conway and I left RR before the RB211 debacle. Stewart Miller the man who rescued RR from that catastrophe worked on the next board to me in those long gone days.
From an engineering point of view, I am intrigued by the 24 (x3) bolt hole fan attachment ring.
Some of the bolts seem to have failed in tension and have been lost, but some are still in the ring, maybe held in place by plastic deformation caused by shear and / or torsion forces. The Ring itself seems perfectly intact.. no cracks or bits missing.
Although this area of the fan assembly is where the separation occurred, any testing of these components will unlikely show any developing cracks, unless all the bolts are crack-tested individually.
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Some of the bolts seem to have failed in tension and have been lost, but some are still in the ring, maybe held in place by plastic deformation caused by shear and / or torsion forces. The Ring itself seems perfectly intact.. no cracks or bits missing.
Although this area of the fan assembly is where the separation occurred, any testing of these components will unlikely show any developing cracks, unless all the bolts are crack-tested individually.
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