Emirates A330 Fan Blade - DXB 18 Oct

[sodski]

I was aboard an EK A330-200 inbound to DXB from BHX last Tuesday, and all had been quite normal until finals.

At what I'm guessing was 300 feet or so, a go-around was initiated. For those that know DXB we had crossed SZR. The go around was started with the usually quick application of heaps of power. This was followed just around 10 seconds later by a very distinct and quite loud bang, after which the number 2 engine was clearly responsible for a significantly changed cabin noise.

I was in Business, and looked out of my window to see that I could now see daylight through the cowling. The poor couple behind me who must have been in their seventies and were travelling to SYD via DXB to celebrate their 50th wedding anniversary, were noticeably shaken and clutching each other.

Completely uneventful (for us in the back anyway) go around and eventual landing after about 20 mins.

A couple of points come to mind though. There was no cabin announcement at all, and the purser or her crew weren't anywhere to be seen. Now, I understand that things in the flight deck would have been fairly busy, but it would have taken nothing for quick reassurance. As a passenger with at least a little knowledge (rotary experience and keen fixed wing interest), I found ,yself having to reassure all those around me, explaining that the crew would have trained all their careers for this and that it was nothing to worry about etc etc.... The crew should at least have had a walk through the cabin to see what the mood was and to be a reassuring presence.

We were met by a full emergency turnout and taxid off the active straight to a remote stand. Doors open and away we go.

I took the following pictures quietly from my phone.

http://img138.imageshack.us/img138/4796/image000va2.jpg
http://img156.imageshack.us/img156/3654/image002fn7.jpg

I wonder where the bits of cowling went to. Some poor chap walking through Deira now has RR stamped on his forehead maybe.

On the local Dubai news the other night, the whole thing was predicatbly denied in full. "Emirates has insisted that none of it's aircraft were involved in any incident at DXB on Wednesday morning this week". Only in Dubai!

I'm presuming that this was a fan blade problem?

[Clarence Oveur]

If a fan blade, or part of it, had departed, there would probably be more than a loud bang and a change in cabin noise. You would no doubt also be able to feel vibrations.

The fan casing should be able to contain a separated blade. It also seem from you pictures that the holes are in the intake. I.e forward of the fan section.

It is possibly damage from a foreign object. Perhaps linked to the GA?

[sodski]

If a fan blade, or part of it, had departed, there would probably be more than a loud bang and a change in cabin noise. You would no doubt also be able to feel vibrations.
The fan casing should be able to contain a separated blade. It also seem from you pictures that the holes are in the intake. I.e forward of the fan section.
It is possibly damage from a foreign object. Perhaps linked to the GA?


Fair point. No reason was given for the GA so who knows.

[Andu]

I spoke to an engineer who met the aircraft when it came in and he tells me there are VERY spectacular photographs doing the rounds within engineering. I suppose it's only a matter of time before one shows up here. The way he spoke, part of the leading edge of the engine intake may well be gracing the roof of someone's factory in Deira.

[sodski]

Would it have been the strain put on the engine for the GA that caused this type of failure?

[Lucifer]

Absolutely not. One engine on its own can cope with a go around.

[sodski]

Absolutely not. One engine on its own can cope with a go around.

I was just wondering if it would exacerbate a 'failure in waiting'.

[keel beam]

I am not familiar with the Trent on the A330 .... but looking at the damage, it might possibly be a pneumatic duct break causing an overpressure in the nose cowl (pressure relief panel not operating as it should). If the Fan blades had let go, then I would have expected damage all around the cowl, but even then not as far forward as the photo shows. Will await further info.

[Lucifer]

I was just wondering if it would exacerbate a 'failure in waiting'.
It could be at a point of using large amounts of thrust that a failure might be more likely to occur, yes, however it would not be correct to say that a go around would cause it in isolation. Many have failed in cruise and climb as well, such as mid-Pacific United 777, and the infamous DC10 that caused hydraulic loss.

[forget]

It also seems from your pictures that the holes are in the intake. ie. forward of the fan section. It is possibly damage from a foreign object. Perhaps linked to the GA?
Forward of the fan it may be, but only a departed blade would cause this type of damage. Given that it shouldn't happen, blade containment and all that - I can see this one going for some time! :uhoh: :uhoh:

Fan relative to nacelle - ( engine's running)

http://i21.photobucket.com/albums/b270/cumpas/trent.jpg

[semper fi]

So would that be damage or no damage?..........maybe they could use it in the next sim check...:}

[gas path]

Not unknown for a fan blade annulus filler to depart company:suspect:
However whether it would do that amount of damage:confused:

[barit1]

Purely speculative - but I have seen a case where a very tough foreign object was ingested, and a fan blade snagged it, tossed it back forward and outboard.

Never saw a duct penetration like this, however.

[lomapaseo]

Purely speculative - but I have seen a case where a very tough foreign object was ingested, and a fan blade snagged it, tossed it back forward and outboard.
Never saw a duct penetration like this, however.

Nothing unique about this inlet penetration. Pieces get thrown forward and sometimes the inlet gets penetrated by the pieces that rebound off the hard engine made containment structure. take a look at the pics from the various similar events in Oz, regardless of the engine model.

[mini]

The story behind this will be interesting when it comes out.

Who will conduct the investigation and where can we read the result?

That may seem a silly question but given the locale... :oh:

[Jetstream Rider]

Forward of the fan it may be, but only a departed blade would cause this type of damage.

Not quite true. I have seen similar damage from a spinner ring that came off and punctured the cowl forward of the fan. The inside of the cowl and the fan were damaged through 360 degrees, but outside just the hole was visible.

That said, I do not know what caused the Emirates failure and I wouldn't want to speculate.

[GEnxsux]

No way a fan blade release. You'd notice it if it was. Kevlar everywhere, rest of fan blades all busted up etc.

Could be an annulus filler release, seen previously on T700.

[slingsby]

Aforementioned annulus filler seems more likely.

http://www.easa.eu.int/home/files/easa_ad_2006_0116.pdf

AD issued 08th May 2006 in regards to T7 on A330 aircraft.

[lomapaseo]

No way a fan blade release. You'd notice it if it was. Kevlar everywhere, rest of fan blades all busted up etc.

Could be an annulus filler release, seen previously on T700.

One single front end view looking at the fan would dispel or confirm this.

and the supporting AD listed, against the annulus filler does not convince me that was the problem here.

[hobie]

One single front end view looking at the fan would dispel or confirm this.


Surely someone has one or two more photo's .... :confused:

[howflytrg]

Quick question as perhaps i am misinformed. Are engine cowlings designed and tested to contain a blade shed event?

[woodpecker]

Yep, bit like a catchers mitt, should hold it but if it doesn't it would be recorded as an error!

[howflytrg]

Thanks Woodpecker, thought that was the case, just had not been mentioned until now. :ok:

[lomapaseo]

Quick question as perhaps i am misinformed. Are engine cowlings designed and tested to contain a blade shed event?


No

The cowling is typically considered part of the aircraft and as such specified by the aircraft installer under part 25 of the regulation. It's function is to streamline airflow as well as to provide fire containment. there is no spedcification to provide containment of debris from the engine.

Lots more could be said about containment, within the engine.

[barit1]

The fan CASE (part of the engine proper) must contain a fan blade failure - the blade will fly tangentially outboard and be trapped or bounced back inboard.

The outer cowl wraps around the case - like lomapaseo says.

[Fargoo]

Some of the photos doing the rounds -
Picture 1 (http://static.flickr.com/121/282208878_eeecbe8e58_o.jpg)
Pciture 2 (http://static.flickr.com/106/282208879_d3d1732ecc_o.jpg)
Picture 3 (http://static.flickr.com/93/282208880_560c23d365_o.jpg)
Picture 4 (http://static.flickr.com/78/282208881_8f62cbe10c_o.jpg)
Picutre 5 (http://static.flickr.com/86/282208884_699a78990d_o.jpg)
Fargoo :ok:

All the photos on one page
Photo page/ (http://www.flickr.com/photos/98001721@N00/)
Can someone let me know if this works ok. ( The photos I mean )
Fargoo :ok:

[Nelli]

Both the page and photos work fine at least for me.

As for the subject, I can only say, Ouch!
Would be interesting to know what caused this:confused:

[11K-AVML]

Would it not be worth considering the reason for the go-around?

[barit1]

Although the photos don't show much of the fan rotor blades, I don't see any evidence of damage there. Typical engineer's response - "More data please!"

[gas path]

Although the photos don't show much of the fan rotor blades, I don't see any evidence of damage there
My thoughts exactly, and also what I was told by one of the RR reps. Although to be fair the day it happened details were a bit sketchy to say the least.

[lomapaseo]

Although the photos don't show much of the fan rotor blades, I don't see any evidence of damage there. Typical engineer's response - "More data please!"

When you enhance the photos you can pretty much see all the fan blades as undamaged (to the eye).

The fan rub strip also appears intact.

Surprising both inner and outer inlet cowl walls are failed. Typically they are not in the same load path.

All I could make out was overload type breakup at the forward ends. The inner sheet aft end is where I would have a closer look.

The amount of material missing is a concern. Much more and the cowl might not be able to survive manuever or air loading. Of course its still only equivalent to an engine out.

It would be interesting to hear of any follow up service bulletins resulting from this.

[Bus429]

I'm only an avionics man but all fan blades appear intact!

[forget]

Not unknown for a fan blade annulus filler to depart company:suspect:
However whether it would do that amount of damage:confused:

Looks like gaspath may be on the right track. I have no idea what annulus fillers weigh, can only guess what they do (fill an annulus) - and I don't know what they do when they let loose, but now I know what one looks like :)

http://www.chem-tronics.com/repairservices/capabilities/V25AF315.pdf

[forget]

But it thought:
All the blades, annulus fillers, and nose cone are still where they should be....
;)

Is that so - A380? Well as you seem to know, please enlighten us all. Is this how it left the factory - or am I seeing something that's not there - literally.

http://i21.photobucket.com/albums/b270/cumpas/Untitled-1-1.jpg

[Mudfoot]

A Google search of "annulus filler" rendered this:

www.matcoinc.com/files/PublicationPDFs/ReExaminationofFailureAnalysisPart12.pdf -

"Case History #6. Aircraft Engine Failure
The fan section of a turbine aircraft engine contains fan blade separators known as annulus fillers, or simply as spacers. The material specification of an annulus filler is usually 7075 T56 aluminum alloy with a painted coating. The highlighted area in the drawing at left represents the annulus filler component, of which there are 22 in this engine. Annulus fillers are attached to an outer rim (rotor disc) by means of insertion."

Apparently, they simply keep the fan blade tips evenly spaced.

Cheers, y'all.

God, I'm beginning to love Google...

[PJ2]

forget;

What to you appears to be missing, (aside from the obvious cowling sections)? I've taken a look at the available photos and, while not conclusive in re annulus fillers, (unless that's the lighter areas between the blades in the photo you've posted), the blades appear in all photos to be intact, though in one photo taken from inboard the engine with almost all blades showing, there does appear to be some leading-edge blade damage...

Cheers,
PJ2

[gas path]

The lighter areas in the picture between the fan blades are the annulus fillers. EK have had an annulus filler let go before, ex GLA diverted to LHR for an engine change. The bright green bit in the picture is part of the nose cowl structure that the acoustic panels 'nail' to.
Now another pure guess here but possibly a failure of the inner barrel acoustic panels due to fatigue causing a heavy surge and subsequent failure of the outer skin. That would also account for damage to the blades.

[JetMech]

Apparently, they simply keep the fan blade tips evenly spaced.

The annulus fillers are merely aerodynamic fairings fitted between adjacent blades. They are there to make a smooth transition from the back of the spinner extension to the inlet of the IP compressor. They do not play a part in fan blade location.

The annulus fillers on the G2 weighed about 1 to 1.5 kg. I would guess that Trent 700 annulus fillers would have a mass nearer 2kg.

[helen-damnation]

Gents,
The rumour is pneumatics :(

[paulkinm]

I have just been looking at this picture http://static.flickr.com/86/282208884_699a78990d_o.jpg (http://static.flickr.com/86/282208884_699a78990d_o.jpg)

Note that the edges of the shattered cowling have been bent inwards towards the fan. It looks as though an object of some kind has smashed in from the outside. Very odd I must admit.
:sad:

[As I See It]

Is that so - A380? Well as you seem to know, please enlighten us all. Is this how it left the factory - or am I seeing something that's not there - literally.
http://i21.photobucket.com/albums/b270/cumpas/Untitled-1-1.jpg


I'd say what you are looking at there is a section of nose cowl longeron which is holding the lower acoustic lining in place, as all blades appear intact from other shots.

If not pneumatics, as is being suggested, then I'd go for failure of the composite skin and any blade damage as a result of debris from the cowl break up.

A blade failure would make that damage look tame and would be radial to the fan not forward of it.

my two p and only As I See It

[paulkinm]

Surely if a fan blade made it's way loose, it would of come out the side aft and not forward as indicated in the pictures. :confused:

[Five Green]

Is that so - A380? Well as you seem to know, please enlighten us all. Is this how it left the factory - or am I seeing something that's not there - literally.

http://i21.photobucket.com/albums/b270/cumpas/Untitled-1-1.jpg

If you are looking at the primed green peice. That is part of the cowling structure spanning the damage gap. You are looking from the outside in and at the back of the doubler (stringer) joinong the rear part of the cowling with the front. This stringer is blocking your view of the fan blades in the 6-8 'o clock pos. If you look in the other pics you will see the fan blades at that position are all there.

[paulkinm]

I think you are right there mate, not that I am in anyway in the business, but that seems to be the reason. What is the material? Looks like some sort of fibre glass or carbon fibre judging from the thread like material in some of the other pictures.

[lomapaseo]

Surely if a fan blade made it's way loose, it would of come out the side aft and not forward as indicated in the pictures. :confused:

The engine containment case prevents it from coming out the side directly in line withe engine. Smaller pieces of It therfore slide forward into the soft skin of the inlet to carve that up some.

It rarely produces inlet damage as far foward as what's shown in the photos.

[Whymeworry]

Three scenarios are considered in investigation, 1. external damage to nose cowl in Birmingham, 2. nose cowl structural defects and 3. violent engine surge. Needs to confirm if the pressure differential at the inlet at the time of the incident can cause such damage. Engine part release is ruled out, cause of TOGA was delayed notification of runway change, engine was not shut down as initially reported

[Seloco]

Can anyone confirm whether the missing bits of cowling exited externally, or through the fan (picking up paulkinm's earlier point about the apparent direction of the rent edges)? Presumably at TOGA power the negative pressure in the inlet is huge and would tend to suck any detatched linings inwards, and yet there is little if any fan damage apparent.

[Scratcher]

To clear up any myths, and I'm a late arrival here, so here's my 2 cents
Those who claim that the fan case can stop a blade are absolutely right, however...
Whilst testing the fan containment shroud, the engine is immediatly shut down, in real life, if the engine isn't shut down straight away then after a few seconds there's a good chance the fan disc could depart...
Now, the fan disc is another matter altogether, imagine something with up to 45 times the mass of a single blade spinning to wherever the heck it likes, Mr. DuPont won't have a chance.
And to clear up any chance that it could've been a 'departed' blade, I took the loberty of enhancing the brightness on this photo, and you can clearly see that the cowl damage is forward of the blades, enjoyyy :p
http://i6.photobucket.com/albums/y205/scratcher8/misc/282208884_699a78990d_ocorrect.jpg

[Flap40]

There seems to be a bit missing just forward of the fan in this shot:-
http://homepages.nildram.co.uk/~jodel/photos/missing.jpg
What is/was it and where has it gone? Could it have detached and then been thrown forwards and out through the casing?

[spannersatcx]

It is an acoustic panel (or rather was).

[Globaliser]

Whilst testing the fan containment shroud, the engine is immediatly shut down, in real life, if the engine isn't shut down straight away then after a few seconds there's a good chance the fan disc could depart...After the fan blade off, doesn't the engine have to continue running for x minutes at xx% power to make it a successful test? Or am I thinking of a different test?

[barit1]

After a bird ingestion test the engine must keep running for a specified time (don't recall exact number).

But after a fan blade release test (usually done with an explosive charge) an immediate shutdown is done. I have even heard of the vibs so bad that the tower shaft driving the gearbox will disengage, shutting off the fuel.

[Globaliser]

Thanks for that - much appreciated.

[lomapaseo]

After a bird ingestion test the engine must keep running for a specified time (don't recall exact number).
But after a fan blade release test (usually done with an explosive charge) an immediate shutdown is done. I have even heard of the vibs so bad that the tower shaft driving the gearbox will disengage, shutting off the fuel.


I will continue to state that this is not correct. The engine is not permitted to be shutdown straight away and must be handled in the same manner that a crew would perform under high workload.

However, whatever happens, happens and is considered in the pass-fail criteria

[barit1]

I have known a couple engines with the compressor discharge sense tube (to the FCU) routed around the fan case so if she shed a fan blade, the fuel flow would quickly drop or even shut off.

In service this device proved more of a hazard than a safety feature, and approval was eventually granted to remove it. :8

[lomapaseo]

I have known a couple engines with the compressor discharge sense tube (to the FCU) routed around the fan case so if she shed a fan blade, the fuel flow would quickly drop or even shut off.
In service this device proved more of a hazard than a safety feature, and approval was eventually granted to remove it. :8

agreed !

I can't immediately think of either an engine test or an actual in-service delay in shutting down a fan blade out event ever having compounded the end result from a safety standpoint

[horsethief]

As far i can see at the pictures it´s seems to me a break caused from inside of the cowling. The outher part was broken out but the iner part seems to be broken to inside. Looking at the bottom of the brake we can found a perfect faliure in the joint. Besides close to the fan there are mising material. A foreing object can do that???
Another consideration: as far as i know generaly there are two bleed air suply sources (LP and HP) fron differents stages of the engine, depending on the thrust.
Maybe a bleed valve didn´t work properly during the low to high power transition resulting in this brake......:hmm:

cheers

[Plank Cap]

Local word on the street here in the Sandpit is explosive failure of the anti-icing plumbing .......

[Jet II]

Another consideration: as far as i know generaly there are two bleed air suply sources (LP and HP) fron differents stages of the engine, depending on the thrust.
Maybe a bleed valve didn´t work properly during the low to high power transition resulting in this brake......:hmm:
cheers

Neither HP or LP bleed air goes through the nose cowl - the only supply of bleed air in that area is cowl anti-ice.

[spannersatcx]

And the bleed air used for NAI is...............

[Jet II]

point taken :ugh:

[Arnie Dan Otherdump]

................Nacelle anti-ice on the Trent 700 is HP3, do I win a banana ? Customer bleeds are IP8 and HP6, ( another banana ? )

[Seloco]

Just for us non-techy types that are following this thread with interest, can I just try to clarify how the nacelle anti-ice system works?

Is it that there is a pipe or pipes that bleed air from the third stage of the high pressure compressor in the Trent core and bring it forward to the annular leading edge of the nacelle? Here its inherent heat (due to it having being compressed) is used to ensure that ice does not form in the nacelle inlet.

Presumably the hypothesis therefore being raised is that at some point along that pipe(s), which presumably run between the nacelle liners and the cowling's external skin, an explosive failure occurred which had the effect of blowing out the nacelle/cowling material on either side.

If this is the case, then presumably the internal lining material was blown inwards and thus inevitably through the fan, although from the photographs this shows surprisingly little evidence of damage.

[spannersatcx]

Of course you do Arnie Dan Otherdump.:D

Seloco, yes basically you're correct. There is a pressure regulating valve in there that should regulate the pressure to around 65psi I think.

[lomapaseo]

Stuck on anti-ice will overtemp the cowl if left on for long times inight have even been stuck open since last turned on.

The inlet wall inner and outer walls are likely at lower pressures than the inside of the cowl and the only explosion would be the noise of it tearing away and going through the engine.

[easyduzzit]

It's actually horrifying reading some of the nonsense that has been typed up on this thread!!!:rolleyes:

First & foremost, it was definitely NOT a blade out, as anyone who has witnessed or inspected an engine which has thrown a blade; & I have only seen engines of much lower power capabilities which sustained this type of event; will show that the inlet & fan, plus casings, is totally catastrophic & beyond any repair, not to mention tail cones shearing off, gearboxes breaking their mounts etc etc, yet the engines still amazingly do generally contain all deadly potential missiles that result from this. They are manufactured & certified to do just this.
However in this case, the fan blades & rubstrip area appear in a beautiful condition totally void of any serious hardened metals or titanium fragments ingestion.
The blades apparently did have a few nicks & marks on some, naturally caused from the ingestion & chopping up of all the acoustic lining plus the outer carbon fibre material of the nosecowl, being sucked into the fan. At T.O. power settings they would have no choice but to go through the fan!
Also "apparently" this engine was only brought back to Idle power due the surge or parameter shifts, & remained at idle normally for the return & landing! If anyone can confirm this I would appreciate it.
My assumptions go along with Gaspath, I think, who said it most likely is a nose cowl inner barrel acoustic lining failure, for what reason no one is yet sure..... ingestion of FOD or material break-up?
I have my doubts about NAI as the supply duct enters the nose cowl at the 7 o clock position which is practically 180 degrees opposite to the panels that have been blown-out/sucked-in? those running around the right hand side of the cowl!.
Most definitely a nose cowl failure, whatever the cause.

[barit1]

Not sure exactly where the a/i valve is located in this nacelle. If the valve is well fwd, close to the inlet lip, it's possible the plumbing failure was on the upstream (supply) side of the valve, and the valve might have been closed the whole time.

But I'm not sure of the layout.

[Jet II]

Anti - Ice valve is under the left fancase just above the starter.

[spannersatcx]

http://i91.photobucket.com/albums/k319/spannersatcx/trent700.jpg

Like here!

[barit1]

Another brilliant theory shot down... :ugh:

Thanks, Jet II and spannersatcx.

[howflytrg]

Quick Q relating to the picture. Trent 700's: IGD's or VSCF Generators? Or dare i ask CSD? Ta.

[easyduzzit]

IDG's!
As one can clearly see by the photo so kindly posted by spannersatcx, the NAI valve sits aft of the fan rub-strip area, noted by the position of the kevlar wrapping(beige yellow material) around this fan frame which is the final containment medium of a fan blade loss & the deadly fragments of metal that result!
Hence, no rupture upstream of the valve possible, as this would be behind the fan & outside the strengthened fan case, & underneath the fan cowls, which were not harmed, nor I believe if the valve were open, there would or should be no pressure build up in the nose cowl as pressure relief panels would pop long before the cowl structure bursts!

[JetMech]

http://i91.photobucket.com/albums/k319/spannersatcx/trent700.jpg

Like here!

G'day people. If you want the story that goes with this picture, check out, http://www.airliners.net/discussions/tech_ops/read.main/171748/
:)

[Techie28]

My assumptions go along with Gaspath, I think, who said it most likely is a nose cowl inner barrel acoustic lining failure

Certainly possible, infront of the rubstrip there is a composite panel, which has been highlighted as missing and there IS an issue with these panels cracking around the rivet heads. I've been involved in 3 repairs of inlet cowlings due to this problem. No Mod Program has been announced as yet i dont think.

Quick Q relating to the picture. Trent 700's: IGD's or VSCF Generators? Or dare i ask CSD? Ta.
Integrated Drive Generators on this engine.


The annulus fillers on the G2 weighed about 1 to 1.5 kg. I would guess that Trent 700 annulus fillers would have a mass nearer 2kg.


No where near that weight, they're lightweight made from composite. (Carbon Fibre i believe). With a small amount of aluminium to hold it in place between the blade. They weigh less than a kilo a piece. They'd just get sucked rearwards. no where near enough mass to escape the fan blades forwards.

[captainpaddy]

Hi there!

I don't know how to post pictures I'm afraid, but if you go to here (pdf):

http://www.aaib.gov.uk/cms_resources/Appendix%201%20figs%201%2D4a%2Epdf

and look at the last picture, you'll see what a fan blade separation would look like afterwards. I think it's pretty clear that this wasn't a fan blade then. :)

The pdf is from the Kegworth crash investigation.

If anyone else can manage to post the picture it would be great!!!

[picu]

Hi there, slightly off-topic:
Would anyone care to explain in simple terms the difference between a Constant Speed Drive and an Integrated Drive Generator? Sorry, I'm not a techie.
Thanks
picu

[Swedish Steve]

A Constant Speed Drive is just that. An input shaft varying with engine speed and an output shaft that is constant speed. The output shaft drives the generator. Usually filled with oil with a pump and a motor, but the BAC111 Spey engine had an CSDS which worked on air!
An Integrated Drive Generator combines a CSD and a generator in one package.
A VSCF is a variable speed generator. No CSD is involved. The frequency wild output is then converted to constant frequency in a box. On the B734 this box was bolted onto the generator, but on the B777 it is in the avionic bay.

Modern big jets all have IDG today. The B777 also has a Back up generator on each engine and a Convertor. Dont know about the A330.

[FlexibleResponse]

If memory serves me correctly, the nacelle anti-ice system is provided by a switchable anti-ice valve that allows warm bleed air into the cowl of the engine nacelle. The air is circulated around the cowl and escapes through the anti-ice pressure-regulating valve to atomsphere when it achieves a set pressure. The NAI anti-ice valves are controlled from the cockpit by pushbutton switches. When selected on, the switchlights illuminate blue when a set bleed air pressure is sensed in the cowl or illuminate amber to notify the pilot of abnormal operation.

If the anti-ice pressure-regulating valve malfunctions in the closed position, one would hope that some sort or overpressure regulating safety valve would release the bleed air from the cowl so that structural failure of the cowl would be prevented.

In the case presented in this thread, we are faced by a structural failure of the engine cowl immediately after the application of maximum thrust for the go-around. The engine does not appear to exhibit any evidence of blade or component shedding that might have precipated the failure of the cowl.

Where do we go from here?

[spannerless]

I haven't had time in my 30 mins allowed for lunch to read all the post's however!!!!

The story goes the cowl may have been bumped at BHX by unkown source, so there maybe a dispute to the second comment.

The aircraft had to do a last minute maneovre (Runway change) in which the aircraft became un-stable in its approach which resulted in a 107% overspeed of Eng 2 and Auto thrust was disengaged along with various fault messages appeared!

So later post's I saw reference Cowl damage induced by engine running at excessive speed may be true.

No blades were lost according to the report but lots of damage to the cowl and the N1 fan!!!!

:uhoh:

[lomapaseo]

here's a postulation

If the anti-Ice was stuck on and operated in an warm ambient temp conditions (low altitudes) , the cowl would overheat weakening the composite walls. Then if the engine were increased to very high power while the aircraft was at low speed, with less ram air into the inlet, the sucking pressure drop across the inlet would act on inner panels and possibly delaminate them at their attachments. Since the inlet walls are made as panels, only the weakest one would fail.

This is only a postulation that might serve to provide some additional thoughts and checks to some confirmed reasoning.

[barit1]

I think you have most of the elements in place, but I might propose a slightly different sequence:

here's a postulation
If the anti-Ice was stuck on and operated in an warm ambient temp conditions (low altitudes) , the cowl would overheat weakening the composite walls.


At low power during descent & approach, the bleed air isn't so hot. But if it was stuck on during the long cruise, that could have damaged the regulating servo in the valve.

But then in the GA with hot ambient, the overtemp/overpressure from the failed regulator could have blown things apart.


Then if the engine were increased to very high power while the aircraft was at low speed, with less ram air into the inlet, the sucking pressure drop across the inlet would act on inner panels and possibly delaminate them at their attachments. Since the inlet walls are made as panels, only the weakest one would fail.

See my comments above.


This is only a postulation that might serve to provide some additional thoughts and checks to some confirmed reasoning.
May I borrow your disclaimer? :)

[steviefartpants]

The Intake wasnt bumped at bhx,there are too many people around to not notice let alone thinking they could get away with it.A reliable source tells me.
Why not wait until the official report as these wild theories are just that WILD.:)

[spannersatcx]

From the Airbus manual: (well I put the pics in!)
30-21-00 PB 001 - ENGINE AIR INTAKE ICE PROTECTION - DESCRIPTION AND OPERATION
1. General
The engine air intake ice protection system gives a flow of hot air from the engine to the intake cowl. The system is in two parts:
- On the core engine: A duct goes from the engine off-take (the 3rd stage of the HP compressor) to the intake cowl interface.
- In the intake cowl, from the interface to a distribution ring in the space behind the lip skin
3. System Description
Between the core engine and the distribution ring the system has two venturis and an engine air intake cowl anti-ice valve (4000DN). Bolts attach one of the ducts to the core engine. Clamps hold the ducts together. Clamps also keep the ducts in position at the rear bulkhead of the intake cowl. A seal is installed in the joints between the ducts. There are two bleed points that are downstream of the engine air intake cowl anti-ice valve (4000DN). One bleed point goes to a high pressure switch (4069KS) on the valve. The other bleed point goes to a low pressure switch (4001DN) on the valve.
In the intake cowl the system has a distribution ring and an inter-bulkhead assembly. The distribution ring is installed between the front bulkhead and the lip skin. It cannot be removed. The inter-bulkhead assembly is in two parts, the inner duct and the outer duct. Each part can be removed. Seals prevent air leakage around the ends of the two ducts.
5. Interface
The system has interfaces with the core engine, the aircraft electrical system and the aircraft instrument system. The low pressure switch (4001DN) gives an indication to the aircraft instrument system when; the valve has opened and there is pressure in the duct downstream of the valve. This signal is stopped when the valve is closed and the duct pressure downstream of the valve decreases.
The high pressure switch (4069KS) gives a signal to the aircraft instrument system when these conditions occur; there is too much pressure downstream of the valve and, if the control function of the valve does not operate correctly. The interface with the core engine gives the system continuity of airflow between the areas that follow; the HP compressor off-take and the lip skin. The engine air intake cowl anti-ice valve (4000DN) has interfaces with the aircraft electrical system and the aircraft instrument system.
6. Component Description
A. The Engine Air Intake Cowl Anti-Ice Valve (4000DN):
The primary components of the engine air intake cowl anti-ice valve (4000DN) are:
- the valve body
- the butterfly shut-off valve
- the pneumatic actuator/regulator
- the electrical solenoid
- the HP and LP pressure switches (4069KS and 4001DN).
All the components are attached to, or installed in, the valve body. A 'direction of flow' arrow on the valve body shows the correct position to install and align the valve. The spindle of the butterfly shut-off valve has a hexagon end for manual operation of the valve. The valve locking pin can be installed through the pointer handle and into a flange on the valve body. This will stop the movement of the butterfly valve.
The valve body has a machined flange at each end to connect the anti-icing ducts. The butterfly shut-off valve is a precision fit in the valve body. The shut-off valve can seal the airflow through the engine air intake cowl anti-ice valve (4000DN). The pneumatic actuator is attached to the valve body. It is mechanically connected to the butterfly shut-off valve and the position switch.
B. The Inter-Bulkhead Assembly (The Inner and Outer Ducts):
The inner duct is made from two different diameters of tube that are welded together. These make a divergent venturi at the forward end. There is a mechanical connection welded to each end of the inner duct. One end connects to the distribution ring, the other end connects to the bulkhead attachment.
The connections at the ends of the inner duct can move to let the inner duct become longer when it gets hot. The bulkhead attachment makes a converging venturi which is a flow restrictor during system operation.
The outer duct is a rigid assembly with three openings. The small opening at the aft bulkhead has a machined connection welded to it. This opening is installed into the bulkhead attachment and can move (to let the outer duct get longer when it becomes hot). The larger opening at the forward bulkhead is attached by a clamp to a connection. This connection is attached to the forward bulkhead by rivets.
The opening on the side of the duct has a seal around it. This seal is pushed against the anti-ice air outlet-grille on installation. An insulation blanket covers the side of the outer duct that is nearest to the inner barrel (of the intake cowl). This prevents damage to the inner barrel (caused by the high temperatures of the outer duct).
C. The Distribution Ring:
The distribution ring is a rigid duct which is permanently attached to the intake cowl. It is in the space behind the lip skin and it connects with the inner duct of the inter-bulkhead assembly. The distribution ring has rows of small supply holes around it.
http://i91.photobucket.com/albums/k319/spannersatcx/nosecowl.jpg
7. Operation/Control and Indicating
Air from the 3rd stage of the HP compressor flows to the engine air intake cowl anti-ice valve (4000DN) through the anti-ice ducts. The first venturi assembly (which is under the left fan cowl) limits the quantity of airflow through the ducts. This makes sure that the engine keeps the necessary performance if the system gets a leak downstream of the first venturi. The first venturi does not affect the satisfactory operation of the system.
The engine air intake cowl anti-ice valve (4000DN) uses the upstream air pressure for its pneumatic operation. The electrical solenoid controls the flow of the upstream air into the pneumatic actuator. When the system is pressurized and the electrical power is removed from the electrical solenoid, the valve controls the pressure to 62 PSIg (427KPa). If the system stays pressurized, and the electrical solenoid is energized, the valve will close. With no upstream air pressure the valve stays open if the electrical solenoid is energized or has its electrical power removed.
http://i91.photobucket.com/albums/k319/spannersatcx/Anti_IceValve.jpg
The air from the engine air intake cowl anti-ice valve (4000DN) flows through the anti-ice ducts to the inter-bulkhead assembly. The inner duct of the inter-bulkhead assembly connects the distribution ring to the anti-ice ducts.
The air in the distribution ring flows out through small supply holes and into the space between the lip skin and the front bulkhead. The hot air increases the temperature of the lip skin and gives ice protection to the air intake.
Used anti-ice air flows to the anti-ice outlet-grille through the outer duct of the inter-bulkhead assembly (Ref. Fig. 003). The seals on the connections of the inter-bulkhead assembly prevent the flow of anti-ice air to other areas of the air intake.
With no upstream air pressure, the engine air intake cowl anti-ice valve (4000DN) can be manually operated with an applicable hand wrench. If the valve is put in the fully open position, the locking pin can be installed in the lock hole. The locking pin can also be installed in the lock hole when the valve is in the fully closed position. With the locking pin in the lock hole the pneumatic actuator (and thus the valve) is locked in position.


In my opinion very unlikely that the NAI system caused the damage, as it's not really anywhere near where the damage has occured, even if the NAI valve was stuck open it just vents overboard anyway.

[lomapaseo]

From the Airbus manual: (well I put the pics in!)
In my opinion very unlikely that the NAI system caused the damage, as it's not really anywhere near where the damage has occured, even if the NAI valve was stuck open it just vents overboard anyway.

I agree with your descriptions, but will add to my own as a devils advocate.

The NAI is designed to add BTU's to the inlet system to raise the inner air temp quite a bit above freezing, such that it is effective at shedding ice on the inner barrel before it builds up enough to seriously damage the engine. This already presumes the flow in the diagram you posted. So if the skin temp against the ice is already 80 deg C. the delta rise on the inside where the anti-ice-air is will be quite a bit above this.

Secondly the system is designed to provide uniform heating even with the inlet and exit flow (baffles etc.) so to me it's a toss up what inner panel is the weakest and fail first.

I realize that I am not adding any more insight here, but rather just extending my original postulation.

Of course I am entirely prepared for a crow sandwich when Airbus releases an all operator letter on this blaming something else :)

[FlexibleResponse]

Spanneratcx's description of the NAI system indicates that there should be no anti-ice air in the cowl between the front bulkhead and the rear bulkhead on the diagram. The anti-ice air should be confined to the cowl lip area only if I have understood the description correctly. Yet the area that suffered the failure of both inner and outer skins in the incident engine is behind the forward bulkhead.

Question; if high pressure anti-ice air at regulated 62 PSI (or higher if unregulated), entered the area between the forward and rear bulkheads, where could this air escape to atmosphere such that a destructive overpressure could not build up in the subject area?

What failure mode of the NAI delivery ducting or regulating valve could result in allowing pressure-regulated anti-ice air or unregulated pressure into this area?

paulkinm's photo
http://static.flickr.com/86/282208884_699a78990d_o.jpg

[spannerless]

The Intake wasnt bumped at bhx,there are too many people around to not notice let alone thinking they could get away with it.A reliable source tells me.
Why not wait until the official report as these wild theories are just that WILD.:)

:=

Steve to clarify!

Emirates reported no damage at BHX but are investigating - Some sort of doubt?

However, an earlier post was most likely on the right lines:-

Some sort of hidden cowl defect or a combination of both a defect and the engine overspeeding, with the engine ingesting its own cowling on approach.

The runways were switched at last minute and the aircraft ended up out of shape on the approach with the crew attempting a go round at 400ft and its engine ending up overspeeding (107%).

[idg]

Would have thought that the overspeed was a result of the blocked inlet not the other way around.

If a depression at the fan was the reason why didn't the cowl 'let go' at BHX when the a/c spooled up for T/O and the depression was the greatest?

At 140 knots or so when the G/A would have been initiated there would have been lots of pressure in the inlet methinks even with the engine going full tilt!

[aerotransport.org]

if not already mentioned:
http://www.flickr.com/photos/98001721@N00/

[FlexibleResponse]

Any feedback from Airbus on the possible cause of this incident yet?

[sodski]

Earlier in this thread, someone mentioned that the GA was initiated due to a late runway change by ATC. Isn't their only one active RW at DXB at the moment? It looked to me like the other one was a mass of sand and hardcore....

[easyduzzit]

SO.... any light on the mysterious Trent700 Nose cowl failure??
It's all gone ominously QUIET!!

[mojocvh]

Indeed when we saw these pics on the corporate site it was a case of WOW how did that happen. It wouls be nice to see the final report. RR also said that the engine performed normally post incident well thats good to hear anyway.