From the ATSB report published today.

"A recent key finding from those examinations was the presence of an area of fatigue cracking within a stub pipe that feeds oil to the HP/IP bearing structure. That cracking was associated with a misaligned region of counter-boring within the stub pipe outlet."

Bearfoil...
 

Good point but I don't agree in this case. In support of your view I would BAN all mobile telephone devices from the assembly areas of aircraft production.

A worrying note was sent out by GE/PandW this last week about oil line integrity in its products. This means that oil lines are being repaired. That means welded. Welding chrome alloy nickel steel formulated to high specs is notably difficult even for those who do it all day and everyday.

In this case the RR oil tube is assymetrical. Weak on one side. Given the vibrations and heat cycles this is subjected too it means that in this case the T972 as used in Qantas 388 it was literally vibrated until it broke.

The oil was probably leaking already due to micro fractures which would have altered the combustion times and set up a further harmonic that wore the spline shaft. Basically the engine was fighting agin itself.

Given all the fancy software design tools the kids use these days it is ironic that we have a failure here that is so familiar and has been with us since 1910.

Ban moble phones in work places a good start. If a company wants to subcontract out work then it should employ a full time qualified engineer on site...even if this is in some far flung part of the planet. This really is a very simple engineering failure.

Rolls Royce will get get stung mightily in litigation over this.

Lomopaseo

I would agree with your assessment. One additional point about these tubes and tube assemblies, chances are they are not produced by the engine manufacturer at all. Given today's world-wide supply chain, these parts are ideal candidates to be manufactured elsewhere, potentially part of offset agreements, e.g., you buy our engines and we will by a certain amount of components from your country.

Manufactured where?
 

The fact is there is only a handful of places where this technology exists.

The one I am familiar with is the reserch dept. run by Dr. Magnus Hasselqvist of the company Siemens in the Swedish town of Finspong.

Of course GE, Siemens and RR are competitors so unless GE and PR will buy the patent and know how from Siemens this will get no where.

You can weld what you want to the alloys Magnus formulates...he is the leader in this field. The formal address is Siemens Industrial Turbomachinery AB in Finspong Sweden and the boss is called Vladimir Navrotsky.

Good outfit.

DERG

I take it you are familiar with the technology surrounding turned tubes, or drilled, as it may.

In the rather sharp pics of the tube's end are two types of odd artifact. The Fractures are straightforward. What puzzles is the brownish off center coving at the lip's edge? It seems to be part of a patent "wear" signature, quite different than the irregular faces of the fractures. It has swirl marks as well. The area at the offset "drill" blunder also seems to have been "worn in" similar to the lip damage. Any thoughts?

I still am not clear on the need for such complex machining if this is but the terminus of a supply line. Everything I see suggests this is one end of a "coupling". If so, the wear evident in the image suggests a poor fit with the mate. Disclaimer: Now that we are all hyperfocused on this oil tube, what of some of the other telltales?

bear

The photograph
 

I am familiar with material failures as any trained engineer should be and moreover I am a free agent so I can comment without prejudice to my financial income.

The insitu postion of the pipe stub is unknown to me but there are several prima facie characteristics that should be noted. The ATSB has already noted some facts and should be read carefully.

The ATSB state this is a feed line. In my view it could be the single scavenge line particular to the bearing case on the Trent. We will see in due course. RR has a patent on this design.

The most significant fact, in my view, is the fractured brown discoloured upper edge closest to the camera. This is an old fracture. Just how old I don't know. But certainly old enough to corrode.

Now this means that oil was leaking through this fracture and hot air was getting in. This would have added oil to the combustion process and cause a very slight delay to the energy transfer cycle viz. a vibration...micro second harmonic. This could be the cause of the spline wear.

What I do know for certain is the Rolls Royce are PARANOID about sharing technology. It is no surprise to me that they have been caught out with this. To be fair they try hard to get staff educated but obviously this simple component caught them out. Sad for UK engineering.

DERG

It's a bit clearer to me. You state that "Oil was getting in, and hot air." Are you saying this opening is part of a closed system? I repeat my question that the end of this pipe appears to be half of a line coupling, and losing the integrity of the line as the coupling failed may have caused the oil to drown the bearing case? Why is a counter bore necessary at all if this is a terminus to a (unpressurized, and un-checked 'feed')?

bear

Bearfoil..
 

Yes, excuse me..got my Toyota Corolla stuck in the snow..four dachshunds..irate wife..and a couple of pet huskies causing distress to all..finally got the thing out and all occupants and home.:ok:

If I am not mistaken the central disc that was exploded out revolves in the opposite direction to the other rotors. I believe this is a feature of RR aerospace turbines if not all in the RB-211 pattern. If someone can confirm this?

So WTF am I taliking about..right? Well we know that this engine is a bypass design and a lot of air does not enter the combustion process. If I am not mistaken I believe this is about 10/15% that gets inducted in the burn section to be mixed with kero.

We know that the oil feeds are subject to hot gas and that the oil should be kept to below 150C. We know that the oil line in question was fractured and I know personally that it was fractured BEFORE this final failure...final failure..shiny crystaline surface on the metal. Old fracture is seen brown oil/corrosion/colour.

Cause of fracture: stress due to harmonic vibration. Only possible cause. Heat cycles added..severe for T-972 'cause of higher energy transfers at max TO weights AND high ambient temps as in S Cal and Australia.

From first principals the engine SUCKS SQUUEEZES BURNS then THRUSTS. The thrust part depends upon the kero/air ratio. The thrust turns the sucker fan at the front. In these new engines all of this is data mapped so the engine KNOWS WTF is going on and adjusts the fuel flow to match.

If you have an oil leak..the turbine oil gets mixed with the kero and changes the burn characteristic..in particular the TIME taken to release X amout of energy. RR are very proud of the fact that their products get more thrust out per total unit mass than the rest. As they boast "High in power, yet low in mass" with " low emissions".

All very well if the kero/air mix is right and the software is not confused. If you have turbine oil mixing with the air then with the kero the whole model is sent to hell. So the thrust turbine thinks it should have X amount of air with a weight of X amount of kero where as the reality is different.
So the different parts of the engine are out of sync.

This sets up a harmonic and the situations gets progressively worse. The vibrations get worse, the temps rise and eventually a part fails due to stress fracture. Of course if the central disc is turning the other way this can make the situation worse.

DERG - A very entertaining scenario. But by what means does the fuel find itself with the oil. Is it a Swedish thing? Is Dr Hasselquvist involved?

Bear and Caad
 

Caad...amzn how simple the faults turn out to be. Just poor part manuafacture,

Bear
As far as I understand the guy who designed this bearing was sure they could not mess up the manufacture.

It is a continuous flow with pressure differentials in play. The system is vented to the atmosphere but only at a start up. In service the way the oil is contained is very clever using centrigul forces. But it DOES require the oil to say in grade..in that sense the oil has to be ON SPEC. Ie right visco and temp and pressure.

That is why oil oxidation due to volcanic dust is a factor in this design. It is in any turbine but esp in this one with this bearing lube design.

Basically the Trent is like a high strung race horse. Wunnerful when all the variables are on the mark.

How does oil mix with kero?
 

Squirts out the fractured oil pipe. Under pressure.

Yes, I can visualise the oil squirting out of the pipe fitting, but how does the fuel arrive in the bearing housing?

Ah, Sorry, I think I have misunderstood again. Are you suggesting that the oil mist from the bearing housing finds its way into the combustion chamber and thus upsets the engine control system? To such an extent that rotor integrity is compromised?

No oil fire in bearing housing, then?

DERG - I'm having a hell of a time following post #88.

Firstly - Aircraft engines must burn a variety of fuels. Within the Jet A spec there is a range of specific gravity, a range of Hydrogen content, thus a range of LHV (BTU/lb) that must be accommodated. Add or subtract a bit of turbine oil, and the fuel/oil properties change very little, compared to the variation that already exists in the Jet A spec. In addition, engines are often approved to run on other fuels - Jet B (higher volatility for arctic use), etc.

Now then - at TO the engine is gulping a few dozen gallons of fuel per minute. The total oil tankage is only a few gallons. IF THERE WERE ENOUGH OIL ENTERING THE COMBUSTION CYCLE to make a measurable difference, the engine would start to overboost. Now what will happen?

The governing function of the fuel control or FADEC or EEC will trim back fuel delivery to bring rpm back to target!

So you see my dilemma: First - how will engine oil at a few dozen psi find its way into the main gas path (several hundred psi), and Second, how could this create overspeed?

CAAD
 

"Yes, I can visualise the oil squirting out of the pipe fitting, but how does the fuel arrive in the bearing housing?"

Because RR use a patented oil bearing case with only one scavenge line. Lube system works by pump, air pressure differentials and centrifugal forces. Totally different to GE/PE. Very precise and neat design.

BARIT..glad you enjoyed my post!
 

Look up "JP8" and you will realise that commercial engines and military engines are two diff animals. If you think the Trent can handle ANY fuel you are mistaken. The way this Trent is designed it gets every last bit of energy from the kerro. Yes I do believe an oil mist would disturb the cycle. We are talking micro/nano seconds.

The days of running jet engines on paraffin are gone with these new units.
They are really efficient.

Remember only about 10/15% of air coming in is used for combustion.

At TO the 972 would gulp a few gallons per SECOND:ok: in the Qantas 388 at full load. Makes ya just slaver your chops don't it!:E

Not sure about overboost cause the software would start to mess with the kero supply. Hence the bad vibes and spline wear. The software will try to correct yes. But all the other parameters don't match the model..hence the stuttering and spline wear.

Did I mention overspeed? I don't think turbine oil was mixing ALL the time but I do think that at the 72K pounds the Qantas A-388 was putting out at TO it was. It would be interesting to know just how much oil had to be added after each flight.

DERG - Modern engines are cleared to use a wide variety of fuels and additives. We say 'fuel'. Not sure what kerro is, or paraffin in this context.

But I am very impressed by the power of your imagination in putting together a scenario whereby oil manages to make its way to the combustion chamber and upset the combustion process to such an extent that hazardous vibrations leading to shaft disconnect result.

I'm with Barit on this and consider it a very unlikely explanation.

But do tell us how you think the oil arrives at entry to combustion chamber. I think I may have asked this before but may have overlooked the explanation.

CAAD
 

Well I call it kerosine mainly because of the smell...fuel..not definitive enough for me.

The disc thingy :E was exploded out because the oil/air was on fire inside the bearing case.

Now you want to know how the turbine oil got mixed in with the kero...

Well if you look at the photo you will see that the fracture on the part nearest the camera is old. So that pipe has been porous for enough time for the surface to be discoloured.

We know this bearing was in the mid section of the engine. The oil is sent around in pipes which we know are subject to fracture. Air and oil was mixing.

So we have fractured pipes feeding hot oil into the engine domain. The reason why I am convinced this happened is the premature wear on the spline shaft.

Thank you for your comment on my imagination. I can see why the disc exploded out,but I use my imagination to apply a reason for the spline wear. All comments welcome by return.

I am intrigued by the Splines wear. It seems reasonable to assume that the TRENT is a well balanced and smooth running machine. I also think it possible to entertain other than lack of lubrication as a partial factor in the loss of Spline metal.

Under the great stress of Climb thrust, the engine is reliant on its internal balance for long service life.

Splines, though accomplishing a "Rigid" coupling, are subject to vibration (chaotic) and Harmonic (synchronous). Each wave upsets the face of Spline, Groove with opposite and energetic input. Hence the loss of metal from the "Crest" of the Spline, and the faces as well.

Under its ultimate Power loading, any impact that impinges on the face/groove of the Rigid coupling produces wear. Almost all of the Thrust from nozzle and Fan are used to propel the a/c, some is lost as friction, it is friction that may have done in the Rigid coupling. The "Tug O' War" between LPT and Fan is "Refereed" at the Thrust Bearing, any load impinges on the Splines, if there is very rapid loading/unloading in this couple, the joint beats itself into the wear rate that caused the AD's IMO

I still think that while very important, the oiling is not the entire answer. It may be that the extra one tonne of max Thrust is a bit too much for the system. That is a very big Supersonic Fan, any vibration and harmonic whether mechanical or 'acoustic' is a very big load.

Just some thoughts

bearfoil

Bearfoil and DERG

In the photograph of the fractured stub pipe in the area of the fracture, I think the surface having swirl marks on it is the result of subsequent forensic examination. That is to say, the swirls come from a radial cutting wheel under coolant spray (may account for the brownish color). The examiners were probably trying to get a better view of the fracture itself, and cut away an unaffected area to enable this. I am sure there are other unreleased photographs that show this component in its original state as found before analysis.

Turbine D

TurbineD

Point taken. However, the 'damage' is consonant with the offset of the 'miscreant drill'. I still think it possible that the 'smoothed' offset is wear induced, perhaps caused by an 'aspirator' affixed to the end of the Stub. An open and unadorned exit of an oil supply/scavenge doesn't fit with a supply that is highly engineered to 'mist' its lubricant.

I could see a rotating tip, an 'aspirator' to induce an aerosol mist into the bearing cavity.

The AD specifically mentions Vanes. Restrictor Vanes. The AD also addresses "clogging" vanes. If there was such a "fan" at the tip of this line, its loss would increase oil supply. If this increase in Oil Supply is too much for the scavenge system, the case would flood with oil. This unscavenged Oil would be noted at Flight's end by line people, or even spoken by a CEO: "There is Oil where it shouldn't be..." Alan Joyce.

If this "imagined" aspirator became "clogged" it would resist the Oil's flow, and perhaps, if out of balance, cause the wear that is evident on this terminus.

I think your point is well taken, but I also doubt any destructive testing would want to 'follow' an out of round (eccentric) fault.

conjecture.

bearfoil

DERG:
Incredible. Do the sums for SFC, you'll find your number would make the Trent a very uncompetitive engine.

(Unless, perhaps, you're referring to total fuel flow for four Trents on the ship...)

DERG - Thank you for that. But spline wear seems to be a problem on all Trent 900 engines, hence the AD. Are you suggesting that they all suffer from oil leakage into the combustion system, causing the harmonious vibration?

CAAAD

You present as an engineer, not a comedian, and I among others very greatly respect your comments. Rather than waste your time on snark, what do you think of my previous post? I expect to learn from you, if you are serious.

Do you think it possible that what looks like a "Misaligned line bore" could actually be wear instead? I say this because there are no telltales, no "bit marks". Any cutting tool will leave a signature if all the bore is to face is the passage of clean oil, The "Offset" is remarkably smooth, suggestive not of Carbide, but wear instread. Thoughts?

regards,

bear

Bearfoil
I am with you on this. I think that shaft coupling spline wear on engines with such limited hours and cycles is very unusual. Splines are coated with wear resistant coatings to prevent premature wear. Today's modern high-bypass fan engines are designed to stay on wing for many cycles and hours before removal, teardown, inspection and component repair or replacement. Some stay on wing for as long as five years of operation accumulating many cycles quickly (shorter routes). Spline wear is not a problem that you normally think of or worry about. Engines are generally removed because of a deteriorating EGT margin. This is generally due to hot section degradation, particularly the combustor and turbine rotor blade tip seals. Obviously operating conditions and individual operators have a lot to do with on wing engine life.
This spline situation on the 900 is very odd indeed. Just some thoughts.

Turbine D

Turbine D

All things otherwise equal, the common (least obtuse) factor would be oiling. Oil can withstand very high mechanical friction, given tolerances close enough to prevent metal/metal contact. If so, the problem distills to lack of oil, or too large tolerances, or some combination. I think the oil is not at fault, so it is most likely wear, beyond limiting Lubrication values. This is to say, Mechanical forces sufficient to diminish Oil's filmic properties. The TRENT is a proven concept, so what's new? More and More Thrust?

I think not. I believe it may have to do with un-attenuated vibration and/or insufficient oiling. Now the Authority has identified Oiling properties as the root, so what follows on is more than likely mitigable circumstances: eg. Vibration.

The RR Bearing mechanism seems to be proprietary. Will the need to know the results of investigation trump Commercial Protections? I would think so.

"We know the problem, but it's a secret, and we fixed it." .....Won't "Fly" I think.

Edit: What are your thoughts on the "Stub Pipe? I would rule out flubbed manufacturing. First, the "Line Bore" mistake would snap any machining tool I'm familiar with. There is insufficient mass to counterbalance the "eccentric". The ledge on the bore is too smoothe to class as defect in manufacturing, I see it as wear induced. The "defect on the tip" is likewise not due to machining, the metal composition of the pipe would have left resistance marks, "chatter". It is too smoothe, suggesting a polish, and why would anyone polish an incision into the lip if the goal was inspection? The fractures are fresh, they are rough, and unsmoothed. The alignment of the smooth "Off-Bore" defects with the fracture location suggest a common axis of wear, suggesting a rotating mass in the bore (aspirator?), or a coupling that is misaligned. All the defects exhibited in the Photograph happened after the installation of the engine, and the beginning of service, IMO. IMO.

One other thing. If a borescope can be inserted into the Bearing cavity, and there are "Vanes" on the Stub Tip, no wear would be noticed. I think this is why the Authority in the AD required an assessment of "Clogging" at the Vanes?

bear :ok:

Bearfoil
Relative to the stub pipe, I inadvertently forgot to mention the most important question of a component failure analysis. Is the material used the correct material? And if it is, is it within specification compositional limits? To determine this, a sample must be extracted for spectrographic analysis as close to the fracture as possible without destroying the fracture surface itself to eliminate off-composition material as being a factor.

Relative to the off-center counter boring, I am having a hard time envisioning how this could happen at the component manufacturing stage. In simplistic terms, one centers the cylinder in relationship to the cutting tool, lock it down and begin the machining process to the required depth.
so I can't figure out why or how it got to the shape depicted in the photo.

Turbine D

Sampling of course, but at the weak point of the part? With potential for corrupting the failure's site? An artifact that suggests "Machining", rather than Sampling? I take your point of course, but again, I see a concentric with the "defect" (wear?) in the bore!!

For me, I try to imagine what is not present in the evidence that may have played a part in failure, so bear with me. The RR architecture is supposedly proprietary, so at this point, we may not see more.

If there was an "Aspirator" on the tip of the Stub, and it fouled, it would have created extra drag on the oil pump. The "Swirl Marks" on the tip may be an artifact of siezed ball bearings, having contributed heat of failure to the wear's face. If the Oil was under Pressure of delivery, the load would be absorbed by a ball bearing contact. Again, I think the Concentric orientation of the tip defect with the bore "Ledge" is telling.

bear

bearfoil - I choose my words carefully, and I try not to give offence and avoid sarcasm. Also I try not to be light hearted but it's a bit difficult when faced with some posts.

But to get to your point.

No, I don't think the offset counterbore is wear, the surface is too uniform. It appears to be a false cut during manufacture.

I do not understand the geometry of the component as depicted in the photo, and I have no idea of the mating parts and surrounding scenery. Hence I find myself unable to comment.

Oh, all right, then, the stub pipe could be an integral part of a housing casting, in which case the counterbore could have been done on a boring machine. An accidental offset of the spindle would have done the trick.

I honestly think we need more information such as a detailed GA or the relevant pages of the Overhaul Manual before we can get down to informed speculation.

I do not believe there is any fancy aspirator type device involved. The counterbore looks tailor made for a pair of O rings. I would not expect lubrication to be by means of a mist. Oil jets more likely.

As Iomapaseo often says, we should leave the real professionals, Investigators, RR and so on to get on with the job. I have no doubt that they will do a terrific job.

Trouble is, I find it impossible not to respond to some of the more extreme imaginings found on here.

Oh, and can we be a bit more careful with the vocabulary please, and only use terms that are recognised in the Trade.

CAAAD,

Recognize "Terms of the Trade"....hmmmm

I am unaware of restrictions relating to terminology, and I don't recognize you as a Mod. Are you one? I doubt it.

"Must respond to imaginings". Your responses to these seem dismissive, You are not opposed to imagination, are you?

You have couched yourself as a "Professional". May be a Continental thing, but in my experience, Professionals do not belittle others, since that is the surest sign of a non-professional.

The idea here is to "......have a little fun...". I would hope that does not mean "at the expense of others."

"Real Professionals". Here I find your comment woefully off target. How in Heaven's name can an anonymous forum have any deleterious affect on the "Work" of the "true" Professional?

"Leave the Professionals to it". Really? May I suggest that they are doing fine, with or without "Tech Log".

I come here to share, to have fun, and practice my writing. Most of all, I am here to learn. Without Imagination, I dare say, there would not be flight. Isn't flight the reason we are here?

respectfully, bearfoil

bearfoil - I'm sorry if I've caused offence. Just to clear the air a bit

I have never couched myself as a 'professional' anything. And not a Mod.

It is often easier to understand a point of view if it is phrased in conventional terminology.

And I repeated a point often made here , that we will not know the details of the investigation until the findings are made known, so excessive conjecture is not very productive.

But I thought my comments re the stub pipe fracture weren't too bad.

Conjecture
 

Please don't make this more complicated than it is. This failure was common in the early part of the 20th century. This is VERY basic mechanical engineering. A 20 yr old second year Mech Eng student can tackle this easily. RR are not noted for sharing information and that is the ONLY problem that second year Eng student would have.

BEAR your post of 5th Dec 2010 15:41 fits my theory. OK the metallurgy is complex but please remember they are seeking to make this engine's mass as LOW as possible.

Also remember that disc thingy?:ugh:(senior moment) that exploded out goes round in the opposite direction to the rest of the internals.

CAAD it is fun to theorise and we, well, I anyway, can do this cause 466 lives were not lost. All Trents? No..not all..but this T972 variant in this situation YES. Specific too.

TURBINE D "so I can't figure out why or how it got to the shape depicted in the photo" Are you serious? It was shoddy work.
What else can it be?

I trust the NTSB. I do not trust RR or Airbus in being open about events.

Please remember that product testing involved 466 people and Qantas was somewaht ignorant of the events going on elsewhere regarding this engine. You will note how the Germans have kept silent through all this apart from a very definite eary statement: "We see no reason to stop flying our 380." That was the day after the accident.

And again: this is a VERY basic engineering failure. OK we have a fancy oil bearing and some high end metallurgy and high energy transfers for total mass of engine..but that is all. We have all the tools to find out what happened.

The biggest problem are the PEOPLE involved. The politics. The cost. And the disgrace.

DERG

On page 70 there is a "Slice" through the TRENT and with it a graphic that shows the LP and IP rotating the same direction, it is the HP that contra rotates, as I view it. A bone to pick with an earlier drawing that shows trajectories out the case of The IPT. The trajectories begin above the axis of rotation. If that is accurate one assumes the Projectiles would have exited to port.

Ferpe's schematic might be the TRENT 700. If the oiling is similar on the 9, take note of the "coupling" at one end of the stub pipe shown by arrow. If it is a couple, the end presented as the stub pipe in the "pics" may be the penultimate opening of the delivery tube, this would indeed provide an explanation of what I see as "Wear" rather than manufacturing "Defect".

The TRENT 700 is 2000 pounds lighter than the GE carried on some 777 airframes, it is this lighter weight that was a selling point for Operators of the TRENT on this Boeing. DERG, light weight is quite important in this accident, as it was in BA038.

One of the contributing factors to the Fuel starvation in 038 was vibration on Thrust select on short final. It is "known" by the AAIB to have shaken loose "Migratory Ice", that impacted the FOHE, causing cavitation and spool down.

Here, with QF32, vibration seems to have been a factor; another would be mechanical stresses focused on this "Connection" feed to delivery. The arrowed oil tube is supplying the dual roller bearings at LPT, so it may not be the correct "Stub Pipe", in question.

DevX has responded emphatically re: "Drawing". My request would be of him to supply a picture (of the TRENT 900) isolating the "stub pipe" in question, to determine if indeed the end shown to the public is one half of a "Quick Couple".


Once again, I note tube architecture that suggests other than the delivery end of an oil supply system, and that the damage appears to be Wear, not "Bench Numpty".

Ever ready to occupy the end of the "Limb", I will say the loss of oiling was caused by the severing of the supply line from the delivery line. I have seen fluid couplings fail with that signature under seriously more docile environments than TRENT @ max chat. Standing to be corrected. Anybody?

bear

Seeking Truth
 

Bear...there is a guy called Page who I call a true vocational professional engineer....see:

Page

I see RR take total responsibility for these engines and Qantas pay money direct to RR per flight hour. The only thing Qantas engineers will know is how much turbine oil was being used when it returned home. They still don't know how much had to be added at destination ports.

Since 1995 I have watched how the unbiquitous MBA graduates have eaten away at engineering authority. When I was the tender age of 22 I could call a STOP at any stage until an issue was sorted.

My own is son is 22 and at university for his diploma. He was taught on the tools from the age of 15. He already has exercised the "STOP" option on his course much to the surprise of his tutors. Makes me, and I have to say his tutors, very happy!

The telemetry affixed to these machines really is a JOKE. All they are there for is to minimise RR costs. They ARE NOT there for the benefit of Qantas or the general public.

Yes Bear the T972 is much lighter than the GE equivalent and this is the reason Qantas bought it...so they get max revenue especially on the routes from California. They had no reason to doubt that RR knew WTF it was doing.

What i really want to know is WTF was done when this machine was up at the Lufthansa facility in Germany for the "C" check. I also want to know why SQ was changeing T970 engines like dirty underwear.

There is NO WAY that RR will meet Qantas in open litigation because we will see what a tin of worms RR has cultivated. For those of us who care about people more than our bonus this catastrophe has torn away our faith.

For those engineers who read this: if the company you work for is taking chances with anything then WALK AWAY. There are plenty of good companies around the world who DO care. Sell up and emigrate. The best guys I know all know work worldwide. Not always for the big players either.

Unlike avionics the mechanical engineering problems are often easily identified to a skilled engineer. Believe me there will be quite a few guys on the tools that knew this T972 was unhealthy. They had mortgages to pay and their supervisors should be no where near a commercial transport aircraft.

Qantas needs to employ a bunch of top notch mobile engineers to get maintenance in hand, rewrite the leasing contract and restructure the chain of command. The way 466 people were used as Guinea Pigs sickens me to the core.

Mr John Page
 

Dept Eng Uni of N S Wales Australia

Failed pipe and oil fire
 

Regarding the broken pipe, there are some statements in a patent taken in 2003 by RR. See US6516618B1
In the text also an oil-fire resulting from a break in the scavenge pipe is discussed.
There are also two drawings which may hint to where the counter-bore could be.

Regards

Another advice
 

http://www.faa.gov/other_visit/aviat.../SAFO10021.pdf

At this point the RR case has collapsed there are so many flaws in this Trent series it is unbelievable. All comments welcome.

I must respond. This SAFO bulletin referenced an OIL SPEC change, and related to subsequent coking on TRENT 700.

The tube in question was an oil vent tube, a design certified to withstand ignition by backflow into the scavenge system.

TRENT 900 Issues: Poor quality control of critical oil tubes manufacture. The fix is agreed to, no new issues have arisen, and I am ready to board Qantas out of SFO.

Poor Form: A very real lack of information targeted to passengers who actually care about the equipment they travel in.

The Bad joint turns out to be a connection after all, involving missed maintenance as well as quality issues.

A poor ATD (attention to detail) in performing mandated inspections following issuance of AD. "Oil Leak? What Oil Leak?"

Another missed opportunity to Sell Safety to the traveling public, instead of offering puerile excuses and "explanations" from twits who think kerosine is to light the Barbie.

bear happy landings

DERG

If you read the SAFO, you would realise that it is aimed at ALL engine manufacturers and ALL operators. How it adds up to "the RR case has collapsed" isn't clear to me.

Perhaps you would care to give it a bit more thought before you try to explain. :ugh:

Diversification
Interesting post!
Did anyone notice in the drawings that the counter bore is actually displaced relative to the outside diameter of the part? Drawing inaccuracy or intentional? Look at Figure 1 in the patent carefully to see what I mean, at least on this particular design.

Turbine D

Turbine D re:
US PatOff 6516618

In the Patent description there is reference to a single scavenge line, where I believe the 972 has a "Gallery". Language describes an interesting mechanism for "Fail-Safe" re: Fire, since the Oil Pressure increases rapidly when Gas Path contents enter the scavenge line. This increase is referenced as "Constantly Monitored", thus allowing a manual cage of the engine, predating I would say even FADEC? I don't notice the offset in the drawing, is it the image on Page One?

The 972 failed pipe is I think a supply line, and the damage to the "Tip" (Which End?) might be either aspirator (Mister), or "external" coupling? It is not clear from released data, either written or pictorial.

Sorry, almost missed the "point"; if "Offset" I would not rule out a designed for "Eccentric" that augmented aspiration of the lubricating Oil. (Misting).

I still maintain that if a mfg. defect, there is patent "Wear", suggesting ongoing leakage, ("Top your Oil, Captain?") a result of missed or deferred Maintenance.

bearfoil