787 engine failure in Charleston, SC

[Flight Safety]

Surprised this hasn't been posted yet.

Boeing 787 Engine Failure Sparks Fire at Charleston Airport | Aviation International News (http://www.ainonline.com/aviation-news/2012-07-30/boeing-787-engine-failure-sparks-fire-charleston-airport)

"Another Boeing 787 engine problem—this time involving a General Electric GEnx turbofan in an airplane destined for Air India—sparked a grass fire at Charleston International Airport during a pre-flight test on Saturday, forcing the airport to close its main runway for more than an hour. The contained engine failure has prompted an investigation by the NTSB, Boeing and GE, maker of the engine now in service with Japan Airlines on four 787s."

[DaveReidUK]

Surprised this hasn't been posted yet.

It was - about 12 hours ago - tagged onto the end of the 787/Trent 1000 thread.

[Flight Safety]

Right, don't know why I didn't look there. :O

[gas path]

Engine shaft sheared allowing the complete LPT assy to move aft.......and out:E.
IIRC sheared at the end of the thread where the coupling nut is!
Same thing happened to a 744 with CF6-80's recently too......must be a GE thing.:rolleyes:
And the AC 773 GE90-115 was a failure in the HPT section...hence the bang!
That was an HPT stage one shroud departing company taking everything aft with it!:8

[fleigle]

Looks like a similar failure, this time on a 747-8.
Second GEnx Failure Under Investigation By GE (http://www.aviationweek.com/Article.aspx?id=/article-xml/avd_09_14_2012_p04-01-495789.xml)
f

[HOVIS]

I suppose the usual suspects will appear on pprune soon enough demanding that the entire fleet be grounded due to Rolls Royce being unable to design a reliable engine...........oh wait, this is an American GE engine. No problem. :ouch:

[BadgerGrowler]

NTSB Urgent Recommendation to FAA : Inspect GEnx Fan Mid Shafts Immediately .

See aviation week :

http://www.aviationweek.com/Blogs.as...23f09a-5cc4-4752-a1cc-6bb1d09569bc

And :
http://www.ntsb.gov/doclib/recletters/2012/A-12-052-053.pdf

Highlights :

- The first failure (GEnx-1B) at Charleston was caused by a fractured forward end of the Fan Mid shaft (FMS), that separated at the rear of the threads.

- The fracture was no fatigue cracking.

- Further examination revealed a faceted, quasi-cleavage fracture morphology that is typical of environmentally assisted cracking of certain high strength steel alloys such as that used on the GEnx FMS.

- A second (zero flight hour) GEnx-1B FMS with a fracture was found during engine checks.

- The investigation into the cause of the environmentally assisted cracking that occurred at both fractured FMSs is continuing.

- The damage noted on the photographs of the GEnx-2B (Shanghai) is consistent with that observed on the engine that failed at Charleston.

- The GEnx-1B FMS is slightly longer than that in the -2B engine. However, the threaded end of the FMS; the manner in which it is clamped with the retaining nut and the assembly procedures, material specifications, and operating environment are similar between the two models. Therefore, the FMS in GEnx-2B engines may be susceptible to the same type of failure observed with the GEnX-1B FMS.

- the NTSB recommends that the FAA require operators to accomplish repetitive inspections of the FMS in all (on-wing and spare) GE GEnx-1B and -2B engines at a sufficiently short interval that would permit multiple inspections and the detection of a crack before it could reach critical length and the FMS.

[lomapaseo]

anyone got any pics of the one in SHA?

[MarkerInbound]

Repetitive inspections of spare engines? Let me get this straight, you inspect what is a brand new engine and after a period of time you have to reinspect it because it may have developed a serious structural fault sitting in an engine stand? I wonder how GE is going to make this up to their customers.

[lomapaseo]

Repetitive inspections of spare engines? Let me get this straight, you inspect what is a brand new engine and after a period of time you have to reinspect it because it may have developed a serious structural fault sitting in an engine stand? I wonder how GE is going to make this up to their customers.


Nothing new in how they will probably handle it like any other engine within a warranty period. Typically such warraties are very genereous as specified in a contract with their new product customers.

In other words business as usual (on the business side).

I believe that RR went through something similar a couple of years back as did P&W.

[Lyman]

MarkerInbound,

." Because of the immediate threat of multiple engine failures on a single aircraft and the availability of an appropriate inspection procedure, there is an urgent need for the FAA to act immediately."

NTSB...

The threat would appear that the crack can progress without load, withut even being on wing. It is "environmental" in nature, the report claims that the steel used in this Fan shaft is susceptible to atmospheric Hydrogen causing an accelerated galvanic corrosive propagation of cracking. They also are cautious that ETOPS is affected, should the shaft fail, and the remaining engine may be subject to 5.5 hours of operation OEI.

This would appear on the face of it to be at least as problematic as the RR TRENT problem with spline wear at the shaft efface.

The link is instructive... and direct, no soft pedalling, as it should be.
regards

[Caboclo]

Is GE building engines out of chinese pot metal these days? How could the engineers possibly have missed this?

[Lyman]

To be clear, the "NTSB" is quoted for the first statement. The second statement, without quotes, is mine. It is a paraphrase. Sorry if it appears as though part of the pdf.

[lomapaseo]

Is GE building engines out of chinese pot metal these days? How could the engineers possibly have missed this?


It isn't the single metal, it's the plural of metals and an electolysis link between them. Things like coupling nuts, multiple shaft materials oils, etc. in a small compartment. The rate of corrosion is highly subjective. the fix is typically protect the metal (coating) and/or change the material.

I suspect that there are quite a few other examples in the literature.

[Lyman]

"While none of the parties involved are able to confirm this, a statement from GE that it has introduced an “improved coating process to the mid-shaft of new-production GEnx engines” would appear to define this as the most likely cause."

Near new, and yet to be mounted engines are in failure? Not Stress, or fatique?

lomapaseo, can you provide several examples of this in the literature?

Since threads are not ordinarily "coated" but need to efface each other clean,
the fix appears to be impossible as described. Perhaps the nut and threads are encapsulated with an applied coating. Not familiar.

[MarkerInbound]

Lomapaseo,

That's what I was implying, if airlines have to ground their brand new planes, GE is going to have to throw tons of money at them to keep the airlines happy. Not good for their bottom line.


Lyman,

I understand the urgency, I've made three legs in a -8. I'm just amazed that GE could create and have certified an engine with such issues.

[Lyman]

Howdy...

Which -8? There are two values for urgency, one involves 25% of the available thrust, the other 50%...

[Machinbird]

Hydrogen embrittlement seems a likely candidate given the described failure mode.
Here is the Wiki on that: Hydrogen embrittlement - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Hydrogen_embrittlement)

I can remember some large spacer washers on the McDonnell F-4 that kept the stabilator centered on the fuselage. These things were way overdesigned to look at them, but they were failing in service because they didn't have the hydrogen driven out of the metal following plating operations. (Improper process specification) You could tell when one failed because the stabilator would then scar the side of the fuselage as it moved. Those massive washers behaved as if they were made of glass!

[MarkerInbound]

I thought the short hand -8 only applied to the 748. The eighth product from Dehavilland of Canada has always been Dash 8.

[Lyman]

Hi

From NTSB....

"On July 28, 2012, a Boeing 787-8 airplane experienced a loss of thrust in the right engine—a General Electric (GE) GEnx-1B turbofan, engine serial number (ESN) 956-121—"

First I've seen that id, but whatcha gonna do?

[Denti]

Boeing changed things with the 787 and all subsequent aircraft so far. It is now just -8/-9 whatever. So far that is true for the 787, 747-8 and 737 MAX.

[Volume]

Boeing Marketing changed to -8, -9 etc.
However, once you really buy the aircraft, you get your full 3 digits.
For example ANA is not operating 787-8, but 787-881. Lufthansa is not operating 747-8 but 747-830. Just the same since 50 years, but marketing needs something new now and then to justify their existence...

[barit1]

Machinbird:
I can remember some large spacer washers on the McDonnell F-4 that kept the stabilator centered on the fuselage. These things were way overdesigned to look at them, but they were failing in service because they didn't have the hydrogen driven out of the metal following plating operations. (Improper process specification)

It's a known issue going back a few decades before the F-4. After cleaning & replating R-985 pushrod-cover gland nuts (Cadmium plate, no less) we always baked them a couple hours to remove hydrogen entrapped.

[DaveReidUK]

Boeing Marketing changed to -8, -9 etc.
However, once you really buy the
aircraft, you get your full 3 digits.
For example ANA is not operating
787-8, but 787-881. Lufthansa is not operating 747-8 but 747-830. Just the same
since 50 years, but marketing needs something new now and then to justify their
existence...

I'm not so sure about that. It's certainly true of the 747 - you will find the -830 series designation, for example, on the Type Certificate.

But for the 787, the only certificated variant (as of yesterday's update to the TC) is the -8, with no reference in the TC to individual customer numbers, which suggests that for this aircraft those are purely marketing and/or Boeing internal designations.

[Lyman]

barit1

In your experience, can the plating process be reversed, the stock re cooked, and then replated? If Hydrogen is entrapped, the fissures have already started, and there is possibility for continued embrittlement, post re-plate?

In one description of the failure, there was reference to "Facets" in the degraded areas. This suggests a propagation of fractures at the level shy of inspection at .05 inches?

This is eerily similar to the Shaft problems RR had in the TRENT, perhaps....

[fleigle]

What I find interesting is that these problems show up in products from main-line manufacturers with decades of experience.
I guess that Boeing and GE can breath a sigh of relief that their overly ambitious production rate has still not happened.
f

[Lyman]

The aah, joint is aft of the hotter, faster bits right? Tell me it is....

[barit1]

Lyman -

Sorry, don't know the answers to these. Regarding the baking process, we baked the parts within a few hours of plating - we heard it was time-critical.

[Turbine D]

I have been a little reluctant to comment on these failures, not knowing for sure what the cause might be. It does appear, however, Hydrogen Embrittlement (HE) may indeed be the cause. In recent newer GE engines (CF6-80C/E or newer), the LPT shaft connects into the Fan Mid Shaft as described by BadgerGrowler. I believe the FMS is made of Maraging steel and the LPT shaft of a different high strength steel. Maraging steel is somewhat sensitive to HE like normal high strength steel and it is only used because of its high shear strength and grain size does play a role in HE. The HE may come from factors in the manufacturing process or raw material (alloy) production, not as a result of operating service. Higher strength is developed by heat treatments but comes at the expense of ductility. Corrosion resistance is also reduced. Typically, high strength steels becomes HE sensitive when heat treated to give tensile strengths above 130,000 psi, perhaps higher for Maraging steel. The part must be subjected to tensile stress as would be the case of a forged shaft. Shafts do not need to be assembled or in service to be under tensile stress. The heat treating process provides most of the residual stresses. Manufacturing processes that utilize acids or electro-plating introduces hydrogen into the part material. I think shafts are electroless plated or vapor deposition coated to prevent corrosion in service.

No matter what, there is a process as barit1 described as "baking". And as he pointed out, parts must be baked within 4 hours of hydrogen exposure, less is better. Parts must be baked at 400℉, and parts must be held at 400℉ for a minimum of 4 hours, longer depending on thickness or size. If the baking process is not done properly, parts can be sitting on the shelf and can begin to show signs of HE. 70% of aerospace components that fail because of HE are related to improper "baking", one or more of the steps outlined above. Since "baking is a batch process, that is more than one component per batch, if one is bad, you can bet the farm that all the components in that batch will be bad. And this takes us to the GE situation.

Boeing essentially put out an original schedule for aircraft build for both the 787 and the 747-800 series. GE, in turn ordered parts to that build schedule, placing orders for long lead time parts first. Then technical issues at Boeing resulted in long delays/postponements for the need of engines. So the engine parts were on hand or partially processed when new delayed schedules for aircraft builds were announced. I am sure they sat on the shelves until needed. Meanwhile, the engine testing and certification programs went on and engines were delivered for flight testing of both aircraft models. IMHO, this is why the problem wasn't discovered during the normal certification process, just an opinion/speculation. Nevertheless, the delay in the program may have hurt rather than helped.

So if the problem is indeed HE, the NTSB AD to GE is to find the rest of the shafts from that "baking" batch or alloy batch ASAP assuming the "baking" process or alloy batch might be the cause. Either way, it would be traceable.

Lyman,
The joint of the LPT shaft to the FMS is not in the hot section of the engine.

TD

[Lyman]

Thanks TD, always appreciate your data. A couple questions though, can you be more specific re: the Plating? You mention 'electroless', I am unfamiliar. Also, by vapor, do you mean plasma or powder coat? I like the explanation of the difficulties GE faced due the assumedly schedule busting resin/spinning process.

Also, you mention the "NTSB AD". The NTSB is not a rule making body, but can recommend only. There is an AD? I could not find it in the FAA site. The NTSB does not write drama, and their concern is clear, there would have to be an AD at some stage, lest the "Optional" brigade start to drag their paws on the ground....

My concern for the location of the joint came about when I read that "The shaft migrated aft, and caused clash with the stators, etc."

We have been down that road, my perplexion comes from any possibility of uncontainment of an explosive nature?

thanks again.

[barit1]

So long as the turbine rotor/stator geometry is designed so that a rotor axial shift creates a clash of airfoils, it's a "fail safe" design. The rotor will never get the chance to accelerate to a dangerous RPM. This is apparently what has happened in the GEnx failures; the low-energy airfoil debris exits through the core nozzle.

However, even this "benign" shrapnel can create a flight hazard - for example, if hydraulic lines are routed within the horizontal stab LE. A thorough FMECA is the answer here.

(FMECA = Failure Modes, Effects, Criticality, Analysis)

[barit1]

Press Release September 14, 2012 (http://www.ntsb.gov/news/2012/120914b.html)

[lomapaseo]

However, even this "benign" shrapnel can create a flight hazard - for example, if hydraulic lines are routed within the horizontal stab LE. A thorough FMECA is the answer here.


ala PA A310 Hamburg

[Lyman]

September 18, 2012, 2:52 pm


AINonline is reporting that GE will use "additional Lead" in the formula for the coating that's expected to prevent corrosion on the FMS thread area. GE reduced Lead in the formulation post GE90, to "protect" the Environment from the deleterious effects of Lead. Nice thought. Now, not so much.

Let's hope that a new EIR is not required, Pesky EPA...

Still nothing regarding a forthcoming AD, other than some sources are saying inspections are "required" (can't happen w/o AD). A Seattle paper is reporting that the Manufacturer is "requested" to inspect...

The operator, Atlas, is saying they are "looking at" the request... Atlas is the only carrier under the jurisdiction of the FAA, supposedly.... (AINonline)

[barit1]

Still nothing regarding a forthcoming AD, other than some sources are saying inspections are "required" (can't happen w/o AD). A Seattle paper is reporting that the Manufacturer is "requested" to inspect...


From a practical standpoint, an OEM mandatory service bulletin (SB) has nearly the same leverage as an AD - in that the manufacturer's warranty may be denied if the operator fails to comply with the SB requirements.

And a strongly worded SB will likely hit the street before FAA can process an AD. :ok:

[Lyman]

Hi barit1

I agree, but I also think it is one thing to face the loss of Warranty, and another thing the loss of an aircraft. The willful evasion of an AD is (can be) a criminal offense.

I am concerned at the lackadaisical attitude of the 747-8 operator. Two incidents of brand new engines spitting their guts out into the slipstream. Smoke/fire.

[Turbine D]

Lyman,

On September 17 the GE spokesman told AIN that all GEnx engines in the field would have undergone inspection by the time the FAA issued its AD this week. The inspection is accomplished on-wing, no need for engine removal unless something is detected.

BTW, electroless plating is a process method of usually applying nickel to a component that has experienced wear, restoring the surface and dimensions to the original limits. Relative to vapor deposition, I am not sure of the exact process used. Since shafts are hollow, the coating is applied to both OD and ID to minimize corrosion from oils, etc., that are vented through the shaft interior.

TD

[Lyman]

Once again, TD thanks for the update.

My concern would be that the shafts were cooked in 'batches', and that the cooking is the required step for excluson of atomic Hydrogen. Since the Hydrogen is a result of a galvanic process, (dissimilar metals), what is the assurance that a field negative exonerates the batch? The additional ingredients involve a humid environment (prevalent), and the location at a machined in situs, (thread root). The fix per AIN is Lead formula coating, not plating, so how is the initial plating tested? The ultrasonics, per GE are only resolved to .05 inches. That is a rather large fissure, and less than that threshold leaves rather a lack of confidence, imo. So then we find that the inspections are recurring at short intervals, to protect the client from fracture and failure. Can this engine be field stripped, like the TRENT and its fifteen modules profile? I am having a time of it, picturing how any effective coating can be applied in the field, without strip. Then there are the threads.

Do you know if the threads are coated prior to join with the FFS? The suspect area is the root of the termination of the helical cut made for the thread in the shaft, again, that seems quite the challenge to "view" on wing....

Thanks TD

[Turbine D]

Lyman,

You are asking questions that can only be answered by seeing the failures first hand, and the failure analysis that would follow, besides knowing in detail the actual complete processing steps. I don't have this information to answer your questions.

TD

[Lyman]

Among others, that is a point I am trying to make. This problem is not complex, nor is it worthy of the shadow people are trying to hide it behind. It has to do with the safety that is currently under attack in our industry.

If someone of your professional calibre is in the dark, we all are.

And that is no place to put the people who pay for the equipment, and pay for the agency that is supposed to protect us from the shadows.

A little sunlight would be a good thing.

[DozyWannabe]

This is not a conspiracy to undermine safety. It's the fact that the overriding concern is to master new techniques to keep weight down. All the companies involved have modelled everything to the Nth degree before a single piece of metal is struck, but it's impossible to get right first time.

[Turbine D]

Lyman,
Are you a metallurgist by background? The problem is complex. There are many processing steps from the time the alloy produced until the final part arrives at engine assembly. Each step must be accomplished within the defined parameters. You make it seem like it is simplistic, it is not. I did post graduate metallurgical failure work on the sudden failures of huge oil storage tanks which turned out to be hydrogen embrittlement, not what was expected at the time. I know how complex these thing can be. Don't lecture me on being in the dark or in the shadows... Good failure analysis and failure problem solutions depends on good first hand data, not on outsider speculation or imagination...

TD

[Lyman]

The last thing I want is to take this discussion into the adversarial. 'Complex' is a highly subjective term; there is an element of 'proprietary' all too often in the realm of investigation which does not serve the public.

People do not fly on 'secrecy' or should not. I should simply have asked where to find more detailed evidence. I will try to be less sensitive to the process of failure analysis as it is practiced.

[barit1]

I would suspect that there is very little "proprietary" in the whole issue, given that the root cause (suspect hydrogen embrittlement) is a well-recognized and long-standing metallurgical phenomenon.

Factors unique to the GEnx (geometry, alloy, design unit stress ...) are the unknowns you and I can only ponder. The exact manufacturing process for this set of factors can only be guessed at by us, even though we probably know the basics.

I for one am content for GE and their FAA colleagues to ferret out the problem (without our help), and complete required inspections on-wing and off-wing. And if outside help is needed, there is a long tradition of consultancy between competing OEM's - to maintain the industry's safety reputation. (I am reminded of Douglas & Boeing helping audit the Lockheed L188 design during its whirl-mode problems fifty years ago).

[Lyman]

I flew on a Holiday Airline Electra into South Lake Tahoe years ago.

The approach was a long straight in, of course, and the turbulence in the basin was extreme. Power was all over the map, and on one sink, the Captain firewalled all four. I was sitting F1' just ahead of the left wing.

I don't know from whirl mode, but One and Two were describing circles in the air two feet in diameter at the spinners. I was convinced both would come off the wing. The extension forward of engine and prop on this aircraft is remarkable, and made for some exciting wobble.

Lost at the casinos, naturally.

[Lyman]

Hi barit1

By proprietary I do mean 'ownership', but not of processes or formulas.

I address ownership of the investigation. It should be the property, in its entirety, of the people, all of them, who have an interest in commercial flight.

Not the owners of the equipment, or the operators, or even the regulatory entity. Everybody.

You are comfortable with GE and FAA. OK by me. Those of us who remember pencil whipped inspections 737 skin, avoidance of AD 447 pitot, and other forms of deceit, what do we do? Were the Thales AA even certified properly?

Some one should care...

[DozyWannabe]

The final reports of incidents and accidents in the West *are* published by independent government agencies. The presence of the manufacturers is simply to take advantage of their expertise - contrary to popular opinion they have no say in the output. And at least since the '80s, whenever a manufacturer tried to, they were told in no uncertain terms it wasn't going to happen.

[Lyman]

DozyWannabe "...published by independent government agencies. Manufacturers have no say in the output."

What is an "independent government agency"?

Manufacturers and their reps are frequently given draft product to edit.

[DozyWannabe]

But they don't have final say on the end product.

An independent agency is just that - separate from the regulator and restricted to publishing proven facts. The industry has experienced two major catastrophes when aircraft were prematurely given the go-ahead to return to service and neither De Havilland nor McDonnell-Douglas exist as separate entities anymore. The lesson taken from those cases is that trying to sweep things under the carpet is more trouble than it's worth.

[Turbine D]

Lyman,
Were the Thales AA even certified properly? They were according to the requirements that existed at the time.

Manufacturers and their reps are frequently given draft product to edit. Wrong! They are often given draft proposals to comment on, not edit. When all the responses are received, the Agency publishes a complete listing of proposed changes or objections received and then either agrees to or denies each change or objection, giving the reason/reasons why or why not...

TD

[infrequentflyer789]

When all the responses are received, the Agency publishes a complete listing of proposed changes or objections received and then either agrees to or denies each change or objection, giving the reason/reasons why or why not...

TD

Usually, yes. BEA does not appear to do so in 447 report at least (and I cannot believe neither mfr or airline commented). Unless someone can point me at the comments I've missed ?

[Private jet]

Doesnt this kind of thing almost always happen with new engine types? Thats a rhetorical question... yes it does.

[Lyman]

TurbineD, But not aircraft specific, I believe. They were "sistered" onto the A330.

TurbineD "Wrong! They are often given draft proposals to comment on, not edit"

Goodness, I hope I am not WRONG. Shall we devolve into parsing words, and furnishing examples of how the Agency has been prevailed upon to erm "issue a MEMO" ? How a request to review has resulted in paragraphs omitted, and Airframers pleased with a lessening of the "Load" ?

It is a long and unproductive tit for tat, and you are at least as stubborn as I am annoying?

[Turbine D]

Lyman,
Lets be clear here:
In the instance of the EASA or the FAA initiating an AD for a problem or event such as the subject of this thread, these agencies may "consult" with the manufacturing folks involved or the airline for factual information, but decide the appropriate action to be taken independently of either party. A recommendation from the NTSB is not required for an AD to be issued, but because of the Charleston event, the NTSB initiated an investigation concerning the GEnx engine problem.

In the instance of either agency proposing changes to certification requirement, aircraft, engines, pitot tubes, avionic equipment, onboard weather radar, you name it, they issue draft proposals and ask for comments and recommendations. Then they decide on each one as I previously noted. For an example, you should read this and then Google to find the detailed response that Airbus gave...

Airbus backs overhaul of pitot icing certification standards (http://www.flightglobal.com/news/articles/airbus-backs-overhaul-of-pitot-icing-certification-standards-336220/)

Private Jet,
Doesnt this kind of thing almost always happen with new engine types? Thats a rhetorical question... yes it does. You gave the right answer to your question. Unexpected issues seem to always emerge regardless of all the testing and certification steps that are taken and all the lessons learned from previous engines. For the GEnx, it would seem to be an inadequacy of a manufacturing process or processes for the component involved, not necessarily a general design problem of this component.

TD

[Turbine D]

Infrequent,
Usually, yes. BEA does not appear to do so in 447 report
The BEA like the NTSB only recommends to EASA or FAA. It is then up to the EASA or FAA to decide to or not incorporate recommendations made. They generally do this through draft proposals and ask the parties involved for comments and recommendation before reaching a final decision.

TD

[lomapaseo]

Turbine D has it right.

It's one thing for interested parties to review a draft and comment privately. It's an entirely different view when the subsequent comments are material enough in nature to result in a disagreement that need be publisized.

Yes the investigating agency has the final say in their opinions to what gets published. However the regulatory agency has the final say in what corrective action is accepted.

Typically the designer/manufacturer/operator is the one that must propose such continued airworthiness actions. If these in themselves are not deemed adequate the regulator may alter them and modify the certificate to the point where the product can not be flown until ....

It's shame that all this what-ifs get burried in a specific incident thread, Like others have said the identification of causal factors in this case are generally agreed between parties the corrective action has been proposed by compentent people and now that the implementation is under way even then the issue remains open to any new data (like more cracks)

Fear not if this becomes a bigger issue then such modification of the certificate will be published for wider expert comment. I do say expert, because most of the coments made by non-experts are disposed in a general sense during publication. If no certificate modification is published than all the questions by those on the sidelines will likely not be furthur addressed than by News releases.

[barit1]

Doesnt this kind of thing almost always happen with new engine types? Thats a rhetorical question... yes it does.

I beg to differ.

For what it's worth: Here's an accident report (http://www.enginehistory.org/Propellers/Aeroproducts/CV-340/AAR68-AC.pdf) with a remarkably similar root cause. It happens to be a skipped manufacturing step in a helical-splined piston, in an established propeller product (not a new design).

[Turbine D]

barit1,
I beg to differ. I think Private Jet was referring to teething problems in general on new engines going into service, not just the GEnx. The most recent serious was the RR Trent 900, A-380 incident. But, others that come to mind include the GE90 introduction on British Airways' B-777 where gearbox bearing wear caused BA to terminate long range service for nearly a year. CFM56 introduction on the DC-8's where the starter shafts sheared due to too tight of geometric tolerances, also, HPT blades clogging with fine sand dust due (blades burned up eventually) to dust holes not being big enough, and I am sure there are P&W examples as well. Annoying but also disruptive problems to the airlines during initial introductions into service...

TD

[Lyman]

Looking for "Teething Problems" in the curriculae....

The TRENT's problem was a lack of (proper) material in the IPT shaft, it is memorialized in the AD. That is not a teething issue, that is a spec/engineering mistake/blunder.

The "misaligned Stub Pipe" likewise is a blunder in machining and QA. I will continue to consider these facts and be sceptical of marketing/promotion issues that fly in the face of quality, and attempts to downplay the seriousness of these issues.

[barit1]

The TRENT's problem was a lack of (proper) material in the IPT shaft,

Which Trent? The 972/A380? The 1000 test bench oops?

And don't forget the RB211/747 IPT @ SFO...

[Lyman]

There was an oil fire in a 9, in Australia, in the test cell. All the Trents have (had) the susceptibility to vibration/harmonics, and poor resistance due to coupling weakness. Too light by several kilograms...

Weight is profit lost, migrating shafts are a potential loss of life.

[DozyWannabe]

There's a bit more to it than that. Lighter and more efficient propulsion is not simply a question of maximising profits, it is also (IMO more importantly) a necessity if aviation is going to be able to keep up with demand in a world where oil is becoming scarcer.

Every introduction of new technology brings with it some risk, but most people are fairly sanguine about that if the long-term benefits are worth it.

I don't think I need add that none of the problems with newer engines have resulted in a fatality.

[viribus unitis]

The FAA's airworthiness directive (http://rgl.faa.gov/Regulatory_and_Guidance_Library%5CrgAD.nsf/0/3B217124C64A00AE86257A800043D51F?OpenDocument) orders

initial and repetitive ultrasonic inspections (UI) of certain part number (P/N) fan mid shafts (FMS) for cracks. This AD requires an initial FMS inspection before further flight. Thereafter, perform repetitive UIs for cracks in the FMS within every 90 days since last inspection. Remove any cracked FMS from service before further flight.

This AD was prompted by a report of an FMS failure and a report of a crack found in another FMS. We are issuing this AD to prevent failure of the FMS resulting in one or more engine failure(s) and possible loss of the airplane.

An unsafe condition exists that requires the immediate adoption of this AD. The FAA has found that the risk to the flying public justifies waiving notice and comment prior to adoption of this rule based on the reported engine failure, the crack find, and that the root cause is still somewhat unknown. We therefore determined that a repetitive inspection interval needed to be established. The repetitive inspection interval is less than the time it would take to process a proposed AD. Therefore, we find that notice and opportunity for prior public comment are impracticable and that good cause exists for making this amendment effective in less than 30 days.

This AD is effective September 21, 2012.(Excerpts from the AD)

[Lyman]

"We are issuing this AD to prevent failure of the FMS resulting in one or more engine failure(s) and possible loss of the airplane."


How does one say "crapshoot" in technese?

As with the EASA AD before it (TRENT 972), the potential for loss of an aircraft is heightened....

Statistician?

[DozyWannabe]

Selective emphasis. The key word is "possibly" - you can have an AD which allows the aircraft to fly while being closely monitored if the chance of hull-loss is relatively remote. Compare that to the Applegate DC-10 memorandum, which stated clearly that "in most cases [this would be likely to] result in the loss of the aircraft". That is the point at which grounding until the AD is applied becomes imperative.

All transportation, from walking across the street to going into orbit, involves a degree of risk management, and everyone who takes an interest is - or at least should be - well aware of that.

[Lyman]

Qantas dodged a shrapnel bomb, and landed successfully. The RR AD had recently been relaxed, and taken advantage of. if the plea to relax the ADhad not been granted, no explosion, by demonstration.

Risk Management? You are heating your seat.

[DozyWannabe]

That's a little melodramatic. If anything, the existence of the AD proves that the system has improved. Compare this to Kegworth, where the engines on the 734 were grandfathered from the 733 design despite having to handle more stress. In that case there was no AD until after the report was published, and another 734 suffered the same problem (although thankfully with no loss of life).

[Lyman]

Your reference to certs piled on existing, are you referring to the TRENT FAMILY?

Sistering specs and expectations for a functionally different powerplant? Gads, not again?

Your reference though intended I suppose to point to an aberration, is evocative of the fallacy that caused the TRENT failure.

Scaling up thrust by scaling up dimensions is a fool's erand, as you eloquently point out, though perhaps inadvertently.

chee ahz...

[DozyWannabe]

There's a lot more to the differences in the RR Trent family than simply "scaling up" - there are significant design differences between them in order to suit their application better. The GP7000 series (the alternative A380 engine) was not a from-scratch design, it was developed from the GE90 and PW4000.

I'm prepared to bet that when the A380-800 series lands for the last time, there won't be a significant difference in reliability or incident between the engine types.

Engines let go sometimes, always have. Because of this, designs are refined during the time they are made. For example, the original RB211 was considered something of a nightmare in terms of reliability initially, but by the time the -535 variant was installed on the B757, they had achieved a level of reliability so good that even the Americans had to take notice.

[Lyman]

There's a lot more to the differences in the RR Trent family than simply "scaling up" - there are significant design differences between them in order to suit their application better.

And that is why some of their certs should not have been "borrowed" from earlier designs,


:ugh:

[oncemorealoft]

Lyman

Which bit of GE do you work for?

A thread about three unusual failures of a GenX engine and you've dominated the last couple of pages with ill-informed mush about the alternative engine choice. Good job!

[DozyWannabe]

And that is why some of their certs should not have been "borrowed" from earlier designs

A cursory Google search doesn't seem to uncover any evidence of this - can you point me to yours?

[Lyman]

Covered extensively in the thread, search there. Briefly, "A three spool is a three spool"

See also why the 700, with blade stator clash, contained the IPT in 'Edelweiss' ex Miami.

The 900 substituted a Stator 'platform', the IPT oversped, and the Islanders collected Titanium. same certificate....

I know, lets eliminate the variables, and model the differentials....

Oncemore....sorry, followed the bunny hole. I'll clean it up..

Actually, the failures are quite similar in nature. 100k thrust cannot be gained by inventing a brand new platform. There was more room in GE's device, but that does not exonerate them from shortcuts to the grail.

[DozyWannabe]

Covered extensively in the thread, search there. Briefly, "A three spool is a three spool"

Oversimplification. If this were the case then the entire Trent series could be grandfathered from the RB211. We know this isn't the case and that each series of the Trent had to undergo most if not all of the certification tests individually.

See also why the 700, with blade stator clash, contained the IPT in 'Edelweiss' ex Miami.

The 900 substituted a Stator 'platform', the IPT oversped, and the Islanders collected Titanium. same certificate....

The overriding feature of the Trent series was to minimise the requirement for variable stators - there's a nice overview here : Rolls-Royce Engines: Trent (http://www.gracesguide.co.uk/Rolls-Royce_Engines:_Trent)

All new and derived designs have kinks that require ironing out - this is accepted fact.

Actually, the failures are quite similar in nature. 100k thrust cannot be gained by inventing a brand new platform. There was more room in GE's device, but that does not exonerate them from shortcuts to the grail.

None of this is specific to the Trent series though - it's just a feature of progress in jet engine design. The "two-spool vs. three-spool" argument is a fallacy as unnecessary as the old "A vs. B" chestnut.

For example, a two-spool CF6-80 notoriously let go during a test at LAX:
FAA to Tighten Inspections on Some GE Jet Engines - Los Angeles Times (http://articles.latimes.com/2006/aug/18/local/me-engine18)

[Lyman]

I must apologize, Dozy...

I thought for the longest time you were purposely avoiding the point made.

I am convinced you miss it on the natch...

[DozyWannabe]

No idea - what's "the point" as you see it?

The fact is that modern engines are statistically a hell of a lot more reliable than their forebears were when they were new...

[Turbine D]

Well, it seems the thread has morphed from the very well defined topic of discussion into a US vs UK point -counterpoint debate. Lyman, on one hand, is looking for 110% perfection on jet engines introductions. OTOH, Dozy is attempting to point out that problems with jet engines go beyond national boundaries, i.e. the RR vs GE debate, a revived but standing debate. So lets look at this.

Under Lyman theory, all aircraft would be grounded tomorrow at dawn because an unexpected event, just might be a possibility, one that doesn't meet the 110% margin of safety. Sorry, the world doesn't work that way. Next time you descend into the "grassy valley" on that winding road, worry about if your car brakes will control the descent or not. It is about the same as if a modern jet engine will perform its task or not. Despite legalistic thinking, nothing is assured to 110%.

Now Dozy brings up an interesting experience at American Airlines regarding an engine that had an unusual engine vibration as reported by the crew bringing the B-767 into LAX. The amateur test theory, as applied to your car engine experiencing the same problem, would be to back it out of the garage into your driveway, and rev it up to red line, at which point, boom! That is exactly what happened at AA. They took the aircraft to a remote area, rev'd it up to red line and boom! The correct procedure was to remove the engine from the wing and perform a look-see to find a HPT disc that had a significant crack out of the dovetail slot region after all those cycles and years. This would be a cost
reduction/elimination decision to the reduce the cost of quality that went amok at AA. The result of the amok was a loss of an airplane, not to worry, the insurance folks picked up the tab.

So lets get back to the original purpose of the thread, should any new information develop...

[DozyWannabe]

@TD

I hope that nothing I've said points to a tit-for-tat international debate!

All I care about is that wherever the donks come from they are designed, tested and built as well as possible...

[Turbine D]

Dozy,
Not at all! Nothing you said is a problem in my mind. All the engine folks do the best they can, always have...

[lomapaseo]

So the SHA event is different !

I asked way back for any pictures since there had been a post that stated that there were some.

It's hard to afix blame without the facts

carry on

[Lyman]

As to confidence long term, would it not be better if the failure had a common cause?

As in, "The GEnx has a tendency to come apart, for varied reasons..."

Or, "Common cause, remedied...."

Carry on....

[Tank2Engine]

More trouble ahead?

Investigators find cracks in second Dreamliner engine - CNN.com (http://edition.cnn.com/2012/09/28/travel/dreamliner-engine/index.html?hpt=hp_t1)

[barit1]

The CNN story is ambiguous as to whether the second 787/GEnx-1B event is a new failure mode -

But post #8 in this thread allows that it is siimilar (FMS crack) to the first. To date, only the 748/GEnx-2B Shanghai case is different, and I don't think teardown results have yet been released for that case.

[Data Guy]

7 Other Mid Shaft failures. Dec 1995 to April 2007.
Notes; Other engine models CF-6s, CF6-50s, CFM56s and CF6-90s.
Only two may be found in NTSB records (Safety Letters, or Accident/Incident database).
Only two (8/18/00 and 12/6/95) had a finding to a cause.
4/1/07. Continental CF6 - 90 series. No Cause. Shop Tear down Report (by QEMY). Source; ASRS report 733184 and SDR # 2007FA0000350 “Upon inspection of the engine, the fan rotated freely, but the LPT did not rotate. BS1 of the engine showed that the HPT was clean, but the LPT was heavily damaged. The engine was shipped to MFG. Initial inspections showed that the fan mid shaft was separated in the axial plane of the HPC S3 disc. The center vent tube was separated in 3 places all aft of FMS separation. An investigation is on going. Shaft Part 1767M75G03." Continental SDR, number and Link > CALA0700137 on 3/20/07. SDR also said investigation by engineering and GE concluded that an omni seal was not installed during engine buildup and that this caused accelerated corrosion of the FMS and subsequent failure. Ed. Note; ASRS Report 733184. No NTSB Accident/Incident rpt --------------------
6/8/06. A-319. CFM56 series. Uncontained Failure. HPT Rear Shaft. No Cause. Source; SDR # 2006FA0000635. “REF: MRD/001/06 - AC suffered an aborted takeoff. Investigation revealed failure and liberation of the HPT rear shaft where a section of material measuring 3.5 inch circumference had liberated around the 3 seal tooth rack. Similar failures have been experienced on engine. Parts are returned to MFG for investigation. Shaft P/N # 9514M71PO4”. Ed Note; No NTSB Accident/Incident Rpt. -------------------------
8/18/00. Carrier UIEA, 747. CF6 -50. Uncontained Failure. Fan Mid Shaft and Stage 4 Disk departed. Cause; air duct. Source; SDR # UIEA0018 . “FLT 7150 - GYE - On takeoff at 400 AGL, Nr 1 engine exploded and had aircraft vibration. Leveled aircraft at 817 feet. Advised tower had an engine fire and declared an emergency. Dumped 30K fuel and returned to GYE. On arrival, determined that Nr 1 engine had an uncontained failure. Analysis of failure indicated airduct failure in area of seventh stiffener. Airduct machined into fan mid-shaft. Fan mid-shaft separated, resulting in uncontained engine failure and stage 4 disk and related hardware departed the engine/aircraft. Duct Part # 9081M40G11”. Ed. Note; No NTSB Accident/Incident Rpt. ---------------------
3/9/98. United DC-10. CF6 - 6. Fan Mid Shaft (FMS) Separated. No Cause. Source; SDR # 98UAL900110 “shut down Nr 3 engine due to aircraft vibration and high temperature indication. Diverted to HNL landed under amber alert. *S/D* the Fan mid-shaft in the engine separated. The primary cause of failure is still under investigation by General Electric”. Ed Note; no further ‘supplemental’ SDR filed. No NTSB Accident/Incident Rpt . ----------------------
10/7/97. Carrier LY2R. 737. CFM56 series. Shutdown On Takeoff. (HPT) Shaft Failed At Seal Teeth. No Cause. Source; SDR # 98ZZZX1899 . “HPT aft shaft failed on takeoff roll at 80 percent N1. HPT aft shaft failed at seal teeth causing extensive damage down stream in the turbine 2nd LPT areas. P/N 9514M71P04.” Ed. Note; No NTSB Accident/Incident Rpt --------------------.
2/22/96. Continental DC-10. CF6 -50. Uncontained failure. Fan Mid Shaft Sheared Off. No Confirmed Cause. Sources; NTSB Safety Letter A-98-125-126, page 4, and SDR # CAL960187 . “A IAH - FLT 0010 - Takeoff was rejected at 100 knots after the Nr 3 engine experienced loss of power. The SDR will remain open for part information pending investigation. Supplement: Preliminary investigation revealed uncontained failure in LPT rotor area. Shop inspection found the fan mid-shaft sheared off. Submitter stated the suspected cause of failure was the HPC rotor air duct failed and rubbed on fan mid-shaft. (x)”. Ed Note; No further ‘supplemental’ SDR and No NTSB Accident/Incident Rpt. -----------------------------
12/6/95. CF6-50. Uncontained Failure. Fan Mid Shaft Failure, rubbing. Cause; Previous Bearing Failure. Sources; NTSB Safety Recommendation Letter A98-125-126. Link > ;http://www.ntsb.gov/recs/letters/1998/A98_125_126.PDF Also a NTSB Accident/Incident Report # NYC96IA036. “The National Transportation Safety Board determines the probable cause(s) of this incident as follows: failure of the number two engine fan mid shaft, due a fatigue fracture caused by a previous bearing failure, and failure of the operator's maintenance personnel to detect the cracks during subsequent inspections”. NTSB Accident/Incident Report. Link > NYC96IA036 (http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20001207X05066&key=1) Ed. Note; The only NTSB report of a engine bearing Failure. 43 others were SDR Reports.
Source Notes; NTSB Accident/Incident database Link > N T S B - Aviation Accidents - Index of Months (http://www.ntsb.gov/aviationquery/month.aspx) search by date.
FAA’s Service Difficulty database and query search; Link > FAA :: SDR Reporting [Service Difficulty Report Query Page] (http://av-info.faa.gov/sdrx/Query.aspx) search by SDR # (control number).

[Lyman]

As of yesterday, 10-04-12, Reuters is reporting that GE has located the problem that disabled the 2B GEnx on the 747 in Shanghai, Atlas.

It appears the LowPressure Turbine nozzle was installed incorrectly. No damage forward of the nozzle, and the incident seems isolated to this occurrence.

I apologize for not linking the story here, operator malfunction.

[barit1]

By KATE LINEBAUGH - WSJ
General Electric Co. GE +0.86% said the failure of an aircraft engine on a Boeing Co.BA +1.52% 747-8 in Shanghai was caused by an assembly error, adding a second source of concern about the company's newest engine.

GE told aircraft operators to complete a one-time, hour long inspection of its fleet of 120 GEnx engines in the next 90 days. The inspection will check whether a part that directs air into the rotating blades of the (LP) turbine was properly installed.

The initial findings indicate that "a stage-one nozzle may have been improperly assembled and became dislodged," a spokeswoman for the National Transportation Safety Board said. "Efforts are continuing to determine the reason for these observations."

The problem is the second found by GE with the GEnx, which is fitted on Boeing's Dreamliner and 747s and whose design is at the heart of the company's coming generation of aircraft engines. The mishaps are a black eye for the world's largest jet-engine maker at a time when the aircraft market is booming and the battle among engine makers is fierce.

Unless these issues are "resolved relatively soon and decisively, they could cause some problems with customers refusing delivery of aircraft," said William Storey, president of Teal Group, a Fairfax, Va.-based research firm specializing in aerospace and defense...

[Lyman]

barit1

"General Electric Co. GE +0.86% said the failure of an aircraft engine on a Boeing Co.BA +1.52% 747-8 in Shanghai was caused by an assembly error, adding a second source of concern about the company's newest engine."

Howdy. This is confusing to me. The impression I have gotten from reading the trades is that the two engines are separate in concern. Now the second problem appears to be piggy backing on the embrittlement problem.

What is your take, barit1?

[Turbine D]

Lyman,

The B-787 engine problem in Charleston was due to a mid-shaft cracking problem. The B747 engine problem in Shanghai was due to an assembly problem where a nozzle vane became loose during TO. The engines are different in several respects and the problems are different. Only the press assumed the Shanghai incident to be the same as the Charleston incident.

[barit1]

Lyman - see posts #86 and #91.

[lomapaseo]

Two separate problems which arguably are not one-offs.

The GE challenge is to identify the two different suspect populations and recommend inspection procedures to minimize any chance of combinations on the same aircraft.

Working on a level of finding each and every one is fine, but the timing must preclude the higher risk scenario of two of any combination on the same aircraft.

I expect that is what is being worked and all we will see on the sidelines is the effect of the inspections and removals

[Lyman]

lomapaseo

Thanks. That makes it quite clear then. I sensed that from some posts I read, it was implied "two different engines" (1B/2B), and that the one inspection exonerated the other fault, by virtue of design differences/type.

So all nx engines are being inspected for both observed failures.

[barit1]

So all nx engines are being inspected for both observed failures.

Given that the two GEnx subtypes are more alike than they are different, that is the only sane course of action. :uhoh:

[Lyman]

So a forthcoming AD regarding a shaft coupling failure is followed by an in service manufacturing process failure that halts a flight. The one preceeding, the shaft problem, is being remedied with new shafts, and the second with inspections to eliminate possibilities of poor manufacture remaining on wing.

Are we talking about the GE? Or the TRENT?

Eerie...

lomapaseo:
"These things have a way of working themselves out within a month.

Give me a ring if anything New"

willdo

[lomapaseo]

These things have a way of working themselves out within a month.

Give me a ring if anything New

[TURIN]

Will these latest engine problems be causing any more delays to deliveries?

I only ask, as one airline I was expecting to have received theirs by now is now looking at mid November at the earliest.

[Mr @ Spotty M]

Which airline was that?

[TURIN]

QATAR.

It was due in July.

[Lyman]

Turin.
Via the Tuesday Reuters article, the chief executive of Qatar said the airline would not accept any of the sixty 787s ordered until "The engines have been modified".

[Mr @ Spotty M]

Qatar, took delivery of its first B787 on Friday.
Will shortly after be flown to Victorville for work on the IFE system, returning for a formal delivery ceremony around 17th or 18th, before the aircraft is flown away to Doha.:ok:

[Lyman]

Were the engines refit with the new shafts?

[barit1]

Seems to me that given the shafts have individual manufacturing records, and that suspect -1B shafts (or shaft lots) have likely been identified and segregated, that NOT ALL shafts (FMS) are replaced before delivery.

That said, we are reminded that the customer is king, and pressure from the customer could upset this plan and force 100% replacement, even if technically unwarranted.

[Lyman]

"We have informed Boeing that we will not take deivery until the 787's have the new modified shaft."

Tuesday, October 2, 2012 Akbar Al-Baker, CEO Qatar AL. (Reuters)

Seems pretty straightforward to me, the client is demanding new shafts. If I buy a new Ferrari, and the crankshaft won't perform, in fact, it fractures on the test drive, I will want a new and different car, not just a replacement crankshaft. The engine would needs be pulled, and all collaterals might be scuffed, or are damaged when the crank lets go.

What about the internals?

Who is the customer, by the way? Al Baker? Qatar? Me and my Family?

Duty of care should be made public, not hushed on the down low. Besides, it is virtually always true that disclosure and honesty work in favor of the principals, in the long run....

[Lyman]

I am not privy to word on your street. Can you link to the IFE issue, and an explanation for Al-Baker's original comments?

I would think Boeing SC would be all over this, and not be pre-empted by anonymous website?

[Lyman]

It certainly is not my street either, the first link is not working, and the second page is a subscription only glossy.

[Lyman]

thanks mike

[9029zds]

I know in the CF6-6 and -50 engines LPT Coupling nut was at the end of the LPT ,,,,the hot end of the engine ,,,stays nice and dry , The Genx is at the front of the engine ,its always more cold and moist (visible during ground runs ). This means it cycles cold to ambient numerous times and creates moisture each time. The Genx flight testing was done at Victorville in the Mojave Desert,where its nice and dry, the failure occurred in the South where its wet and humid. If the LPT coupling nut was over torqued, or the threads damaged in handling or manufacturing, and the Anti-cease is now hygroscopic, I suppose this could create accelerated corrosion, but I think it is more likely since the short time on these engines that they were damaged upon assembly. Worst case would be a design flaw of having chosen to put the coupling nut in front ..........I don't know if the GE-90 is designed in this configuration? But I would assume this allows replacing the propulsor easier?

[barit1]

I know in the CF6-6 and -50 engines LPT Coupling nut was at the end of the LPT ,,,,the hot end of the engine ,,,stays nice and dry , The Genx is at the front of the engine ,its always more cold and moist (visible during ground runs ). This means it cycles cold to ambient numerous times and creates moisture each time.

Partially true. More to the point, the CF6 family (-80s too) have splines w/ coupling nut at the AFT AND FWD ends.of the FMS.

Thus the GEnx-1B thread cracking issue seems to be more related to its unique chemistry/metallurgy, and NOT to its non-unique cold-end location. :8

[Lyman]

The site of the leading fracture was at the "terminus" of the thread root on the fMS. This suggests a couple things. First, a machining issue, where stress is allowed to focus at the tooling insult. This could also lead to susceptibility to degradation via corrosion, and failure. The problem is that corrosion that happens so quickly seems unusual.

Since all failures happened on the ground, my first guess would have been FOD.

As with the RRTRENT spline AD, the possible link of coupling issues with powerful vibration and consequent failure of downstream internals is present with the GE.

The underlying issue may be a flirtation with minimum materials, both dimensionally, and inadvertently, in spec, and unproven economics.

The 2B is fit on the puffing Boeing, the 1B on the Boeing that has pneumatics independent of bleed air. The 2B is nine inches shorter, and has one less LPT stage, case in point?

Edit to correct, the 2B is the shorter engine...

Also to say that what goes through the engine is not air, but MASS.

4000 pounds of it, each second. That they stay together for the most part is a triumph. Hat's off, to all the engine builders....

[Turbine D]

This suggests a couple things. First, a machining issue, where stress is allowed to focus at the tooling insult. This could also lead to susceptibility to degradation via corrosion, and failure. The problem is that corrosion that happens so quickly seems unusual. And, As with the RRTRENT spline AD, the possible link of coupling issues with powerful vibration and consequent failure of downstream internals is present with the GE.
The underlying issue may be a flirtation with minimum materials, both dimensionally, and inadvertently, in spec, and unproven economics.
I think these observations are conjecture without any data to support them, whatsoever.

The fan midshaft cracking and fracturing incidents on the Boeing 787 (GEnx-1B) were traced last month to a new, lead-free coating that allowed the component to corrode rapidly under certain conditions. GE switched to a leaded coating already used on the GE90 to correct the problem.

The problem on the 747-8F (GEnx-2B) has been traced to the Stage 1 LPT nozzle assembly problem which permitted one or more of the nozzle segments to shift aft contacting the Stage 1 LPT blade rotor during the early stage of TO.

The GEnx-1B engine used on the Boeing 787-8/-9 is 184.7" long and consists of 1 Fan, a 4 stage LPC, a 10 stage HPC, a 2 stage HPT, and a 7 stage LPT.

The GEnx-2B engine used on the 747-8F and 747-8 Intercontinental is 169.7" long, and consists of 1 fan, a 3 stage LPC, a 10 stage HPC, a 2 stage HPT, and a 6 stage LPT.

The HPC and HPT are common to both engines. The fan diameter is ~7.0" larger on the GEnx-1B verses the GEnx-2B. On both engines, the fan, LPC and LPT rotate counterclockwise relative to the HPC and HPT.

[TURIN]

The 2B is fit on the puffing Boeing, the 1B on the Boeing that has pneumatics independent of bleed air.

At the risk of being a pedant, strictly speaking the 787 has no pneumatics (IE The application of pressurized gas to affect mechanical motion).

Only the air conditioning system uses air from electrical compressors.

I think...:O

[Volume]

strictly speaking the 787 has no pneumaticsExcept for the engine anti-ice. Which means for the engine: there is a provision to extract hot compressed air from its core.

[barit1]

(Speaking from a total lack of 787 detail knowledge...)

How are wings etc de-iced on the 787? Electrically?

If so, why can't the engine inlet likewise be electrically anti-iced? :confused:

BTW, thinking of the goose/gander differentiation, is the Trent 1000 treated the same? :confused::confused:

[Lyman]

GE plant makes changes after engine incidents - Business Courier (http://www.google.com/url?sa=X&q=http://www.bizjournals.com/cincinnati/blog/2012/11/ge-plant-makes-changes-after-engine.html&ct=ga&cad=CAEQAhgAIAAoATAAOABA0r3lhAVIAVgBYgVlbi1VUw&cd=dbXwk47BcHM&usg=AFQjCNEtc5Myqc7wjpJ_gIAJ5bM43KiHMA)

[Pub User]

How are wings etc de-iced on the 787? Electrically?

I believe so, yes.

If so, why can't the engine inlet likewise be electrically anti-iced?

Not sure. Perhaps it's because the pipework is very limited, or the response time of hot air versus electric heating, or the temperature itself.

[gas path]

787 the only bleed is a 2 inch duct for the NAI. The wing leading edge slats 2,3,4 5, and 8,9,10,11 are electrically heated. Symmetrical pairs and also symmetrical sections.
As for the NAI it's a lot simpler to run a small length of duct!:8

[barit1]

Thank you, gas path.

[Lyman]

Did not know AirFranceIndustrie was heavy into engine maintenance

Air France-KLM Sees Engine MRO Deal with Rolls Royce in 2013 | Fox Business (http://www.foxbusiness.com/news/2012/11/15/air-france-klm-sees-engine-mro-deal-with-rolls-royce-in-2013/)

[barit1]

Forty years ago the ATLAS consortium (AF, LH, IB, Alitalia, and Sabena) pooled resources to maintain early widebody fleets. Most of ATLAS had bought the DC-10-30, although AF did not. Yet the AF shop performed heavy maintenance on the CF6-50 engine for the other consortium members.

Of course a year or two later AF started flying A300s - using the same powerplant package as the DC-10-30.