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Why not replace pylon?
Why put a good engine on a compromised pylon? Engine and pylon will have to be removed at destination anyway. Then good engine and pylon will have to be reinstalled.
If there's any concern for wing integrity, inspection should be done before next takeoff. The locals can set up a heated shelter over the affected area as was done in Iqaluit. |
Today the BEA has this
Les conditions de convoyage de l’avion vers un autre site en Europe sont en cours d’étude, afin qu’il puisse y être réparé et remis en service commercial par Air France. A noter que devant la complexité logistique de ces différentes opérations, le calendrier prévisionnel s'étalera sur plusieurs semaines. Airplane ferry to a European location, for repairs, is under study. Expect to take "weeks" [understood: before it is back in service]. I'm also curious, eventually, who gets the bill to cover loss of revenue? |
Originally Posted by lomapaseo
(Post 9921495)
I take it that the word in the press "ballast" applies to more than just dead-weight balance but also covers the need to balance drag effects within the safe operational capabilities of the takeoff and flight.
I suspect that the pylon is structurally sound (no large rotor seizure effects) and that many of the tubes and wires will not be needed and just be discarded/capped. The complete pylon might be replaced after the ferry flight The CoG issue can be compensated for with fuel and ballast and the missing drag should be well compensated for by the missing thrust. |
Originally Posted by pax2908
(Post 9921655)
Airplane ferry to a European location, for repairs, is under study. Expect to take "weeks" [understood: before it is back in service].
The press release also mentions that the engine will be sent to the GE facility at Cardiff for further analysis once the onsite team has finished with it. |
With regards to the pax, it was the airline's decision not to deplane them, there were in excess of 500 beds ready and waiting to be used if required.
The aircraft is currently parked in front of the former Luftwaffe hangar as there are no hangars big enough to wholly accommodate anything bigger than a DC-10. Goose Bay handles trans atlantic diversions on a regular basis, nothing much different about this one (other than a slight deficiency in the propulsion department). The Lancaster that passed through on it's way to the UK a few years ago raised more interest locally than this. |
Originally Posted by Harry Wayfarers
(Post 9921425)
Providing that the appropriate engine hoists are in place, remember the worldwide DC10 grounding follpwing a seriously fatal accident because operators had been changing engines with fork lifts.
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I think the main issue is wing flutter. Missing (part of) an engine will significantly change the eigenfrequencies of the wing and could lead to all sorts of nasty bending and torsion problems in flight. The CoG issue can be compensated for with fuel and ballast and the missing drag should be well compensated for by the missing thrust. Although in theory it would 'might' be possible to 'paper certify' a missing engine configuration that would surely cost a lot more (time and money) than using a real engine as planned. |
Although in theory it would 'might' be possible to 'paper certify' a missing engine configuration that would surely cost a lot more (time and money) than using a real engine as planned. That said, loss of the engine and recovery to a landing imposed by an emergency would be considered quite differently than a planned ferry flight without engine and pylon. |
From the BEA website:
https://www.bea.aero/en/investigatio...tion-11102017/ BEA Information - 11/10/2017 This is a courtesy translation by the BEA of this Information. As accurate as the translation may be, the original text in French is the work or reference. Press Release n°4 It has been decided to remove the damaged engine in Goose Bay (Canada) in order to preserve its integrity for future investigations. This operation will be carried out by teams from Air France and Airbus before sending the engine to Cardiff in a General Electric facility where the BEA teams will then go to continue their analyzes. The conveying conditions of the aircraft to another site in Europe are being studied, so that it can be repaired and put back into commercial service by Air France. It should be noted that, given the logistical complexity of these various operations, the forecasting schedule will last several weeks. The search and recovery of detached components of the damaged engine is still ongoing in Greenland. |
I guess also installing a dead engine allows the situation to be replicated (if it was not already done for certification), and crews trained, of a 3-engined takeoff, not only in the sim but on the Airbus prototypes at Toulouse.
No expert, but presumably start the roll with the two inboard engines, then feed in some extra power from the remaining outboard engine once the rudder becomes effective. |
To paraphrase: Various options for getting the aircraft back to Europe are being considered (i.e. a decision to 3 engine ferry it back has not been made). Timescale for all of this is several weeks.
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Good point - all of the 3-engined-ferry speculation appears to be based on the Reuters article from a couple of days ago, quoting unidentified BEA sources.
Given that the aircraft won't be flying anywhere unless and until it has been established that there is no airframe damage that would affect the safety of the flight, that doesn't rule out fitting a new, operational engine (and probably a new pylon) to allow a 4-engined ferry. Strictly speaking, provided the measures taken to recover the aircraft to France don't compromise the investigation, how and when it's done is none of the BEA's business, it's up to Air France, Airbus and the regulators. |
FROM WSJ
By Andy Pasztor Oct. 12, 2017 11:18 p.m. ET 0 COMMENTS U.S. air-safety regulators have issued an emergency order requiring airlines to inspect engines on roughly 120 Airbus EADSY 0.25% A380 superjumbo jets world-wide, prompted by an engine that violently broke apart during an Air France... flight at the end of September. The safety directive issued Thursday by the Federal Aviation Administration covers all engines manufactured for Airbus SE A380s by a joint venture comprising General Electric Co. GE .... and United Technologies Corp.’s UTX ... Pratt & Whitney unit. The partnership supplies engines for roughly 60 percent of the global A380 fleet, with Emirates Airline operating the majority of the affected four-engine, double-decker aircraft. The move by the FAA, which certified the engine as did European regulators 10 years ago, requires inspections to start as quickly as two weeks, depending on the number of trips they have flown. The directive follows a nonbinding service bulletin issued by the engine alliance. |
What exactly will they be looking to find?
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https://www.faa.gov/aircraft/safety/alerts/ -- http://rgl.faa.gov/Regulatory_and_Gu..._Emergency.pdf
https://ad.easa.europa.eu/ -- https://ad.easa.europa.eu/blob/2017-...S-2017-21-51_1 DATE: October 12, 2017 AD #: 2017-21-51 Emergency Airworthiness Directive (AD) 2017-21-51 is sent to owners and operators of Engine Alliance (EA) Model GP7200 series turbofan engines. Background This emergency AD was prompted by an uncontained engine failure that occurred on an Engine Alliance (EA) GP7270 turbofan engine. The failed engine had 3,527 cycles since new, which is a relatively high cycle engine. The actions specified in this AD are intended to prevent failure of the fan hub, which could lead to an uncontained release of the fan hub, damage to the engine, and damage to the airplane. [...] (g) Required Actions (1) Perform a visual inspection of the fan hub, in accordance with the Accomplishment Instructions, paragraph 1.B., 1.C., and 1.D., of EA Alert Service Bulletin (ASB) EAGP-A72-383, Revision 1, dated October 12, 017, at the times specified in paragraphs (g)(1)(i) through (iii) of this AD. (i) For fan hubs with 3,500 cycles since new (CSN) or more, inspect within 2 weeks of the effective date of this AD. (ii) For fan hubs with 2,000 CSN or greater and less than 3,500 CSN, inspect within 5 weeks of the effective date of this AD. (iii) For fan hubs with less than 2,000 CSN, inspect within 8 weeks of the effective date of this AD. (2) If defects or damage to the fan hub are found that are outside of serviceable limits, remove the hub from service and replace with a part that has been inspected and found airworthy in accordance with paragraph (g)(1) of this AD, prior to further flight. Serviceable limits are defined in the Accomplishment Instructions, Table 1 of EA ASB EAGP7-A72-383, Revision 1, dated October 12, 2017. (h) Credit for Previous Actions This paragraph provides credit for the actions required by paragraph (g) of this AD, if those actions were performed before the effective date of this AD, using EA ASB EAGP7-A72-383, dated October 7, 2017. [..] P.S.: Andy Pasztor writes in the WSJ and on Fox Business: "requires inspections to start as quickly as two weeks, depending on the number of trips they have flown". "start" clearly should read "be completed". Reuters gets it right. P.P.S.: From the Andy Pasztor article: The same family of engines experienced an unrelated safety problem five years ago, prompting a previous FAA airworthiness directive. In November 2012, an Emirates A380 departing Sydney had an engine shut down on its own at about 9,000 feet. The plane returned to the airport without any passengers injured. But a subsequent investigation by Australian authorities revealed that unexpectedly high temperatures stemming from a poorly designed nozzle resulted in significant internal damage. Two years earlier, the engine manufacturer had issued a service bulletin calling for a replacement of the suspect parts with new, more durable components. Following the incident, the FAA issued a mandatory directive requiring inspections and removal of damaged parts. |
Originally Posted by RickNRoll
(Post 9923383)
What exactly will they be looking to find?
The FAA said the directive, an interim measure, was prompted by the failure of the fan hub on the affected engine on the Air France aircraft. “An investigation to determine the cause of the failure is on-going and we may consider additional rulemaking if final action is identified,” it said in a statement. Depending on the number of flight cycles, the inspections must be performed within the next two to eight weeks https://www.reuters.com/article/us-a...-idUSKBN1CI0CI Edit - it appears Musician beat me to it... |
tdracer, I edited my post a lot after posting (all those postscripts), so likely you actually "beat" me, without me noticing.
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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 ?
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From the AD: "3527 = relatively high cycle engine"
This below could be interesting (?) http://www.iba.aero/wp-content/uploa...e-May-2017.pdf |
TSB update
UPDATE: TSB Report#A17A0063: F-HPJE, an Airbus 380-800 aircraft operated by Air France, was conducting flight AFR066 from Paris/Charles de Gaulle, France (LFPG) to Los Angeles, CA (KLAX) with 24 crew members and 497 passengers on board. At 1349 UTC while in cruise at FL370, the flight crew declared a MAYDAY when fan and inlet components of the number 4 engine (Engine Alliance GP7270) separated from the engine. The flight crew shut the engine down and diverted to Goose Bay, NL (CYYR) where a landing was carried out without further incident on Runway 26 at 1543 UTC with ARFF standing by. Substantial damage to the number 4 engine inlet section was visible, as well as visible damage to slats and fairings inboard and outboard of the number 4 engine. A runway inspection discovered debris on the arrival runway, which needed to be removed before the runway could be reopened. The Transportation Safety Board (TSB) of Canada, Bureau d'Enquêtes et d'Analyses (BEA) of France, and the National Transportation Safety Board (NTSB) of the USA deployed investigators to CYYR. Advisors from Air France, Airbus and Engine Alliance (specialists from Pratt & Whitney USA and General Electric) also travelled to CYYR to assist. The Flight Data Recorder (FDR) information was used to confirm the area of the engine fan separation to be approximately 150 kilometers southeast of Paamiut, Greenland (territory of Denmark). Danish authorities delegated the investigation to the BEA. |
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.
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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. . |
Originally Posted by WHBM
(Post 9923798)
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.
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. |
Originally Posted by CONSO
(Post 9923352)
FROM WSJ
goes on . . . |
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 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. |
Originally Posted by Kenty1952
(Post 9924042)
Aircraft engineers - How long would an inspection like this take on each aircraft? Would you expect it to affect (eg Emirates) schedules having to complete this in 8 weeks on approx 90 aircraft?
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. " 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 |
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".
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...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. |
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. |
Originally Posted by lomapaseo
(Post 9924161)
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no
Fed Ex had early orders but these were NTU |
The Fedex order was for the freighter variant which was proposed but never built.
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Originally Posted by atakacs
(Post 9924801)
Are there any N registered a380?
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 |
Originally Posted by The Ancient Geek
(Post 9924816)
The Fedex order was for the freighter variant which was proposed but never built.
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 |
Re outstanding A380 deliveries, as far as I can tell the Qatar plane, (A7-API due for delivery in December) is the only one not to be RR powered.
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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. |
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. |
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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