Remember - In the case of IP rotor, apparently protection is provided only for an intact rotor (my emphasis). If the IPT becomes detached, then the EEC has no clue what the IPT is doing, since the phonic wheel is on the IPC shaft.

But as we have previously discussed, a rapid N2 unspooling without like N3 change is indicative of mechanical failure (e.g. IPT detaching), and there seems to be the potential to "catch" this in the software before destructive overspeed occurs. In QF32's case, there is an apparent six-second window.

Bear, thanks for the explanation of the EEC logic for a three spool engine.

Is this common on all three spool engines or unique to the Trent 900? It seems rather odd to me but I don't profess to understand the EEC logic on a 3 spool design.

N3 Speed is furnished by the dedicated Alternator, which is powered through the gearbox by the HP Rotor. Two separate single Phase N3 windings supply N3 speed to each of the two channels in EEC. EEC utilizes this data to monitor speed, control the engine, and sense N3 Overspeed.

If there is a total loss of Shaft speed signals, EEC generates a "synthesized pair of shaft speed signals" (N1 and N2) for the cockpit, and uses N3 actual to "maintain transient Control." Turbine D, this is book on the TRENT 900, the others, I do not know.

The Video
 

Here we go...you will like this...

Captain Fantastic

Hell of a mess that engine made.
Holes all over the place.
Shame the Bayesian sophists were not on the 'plane.

This is as far as I go with this unless we get yet more WET replies.
This is where I and the BABUSHKA drive shafts of RR say a final goodbye.:suspect:

I can assure you that stockholders have no extra information for their satisfaction that hasn't already been posted here. Big investors - maybe, but I suspect not, they are interested in finance not engineering anyway.

As to assurances, as pax, yes they would be nice, but I'd rather they didn't bother assuring me that the issue was fixed if, in fact, it isn't. From what's been discussed on this often fascinating thread, I'm not sure it is fixed, yet.

With an investor hat on, I think my biggest concern would be that even if the current AD regime has plugged the safety gap, how are RR making a profit on PBH contract on an engine that only does 70 cycles on the wing ? If the engine is safe but it and its contracts become a financial millstone round RR's neck, then it's no better for the company.

It's all good
 

I see your vintage here on PPRuNe is about the same as mine. Funny, what drew me in was another TRENT goof. I still don't see any satisfaction re: the "Mystery Fuel" on BA038.

It is par for the course that given enough time, and sufficient urgency to travel, SLF pick up their carry-on, there teeny bottles, and launch. It truly is a safe way to mobilize, and it is also par for accident/incident threads to start loud, and end with a whimper.

Such is life in the big world of air travel. It isn't as safe as it could be, but it is very very safe, for all that. The sand in the knickers is it could be better. It is shy of the mark for defensible reasons, but I have never thought money should be in there, anywhere. Not even if facing Banko, as RR may well be. They have chosen the standard path, the way of least complaint, the way of wink and a nod with people who should be a bit more stern with the Corpos.

Nothing will ever diminish the level of sheer disaster QF32 faced that day in November. Nor will anything bring back the folks aboard AF447. We are entertaining mechanical doo doo, but Pilot Error is in there as well. Used to be, a Captain could tell Juan Trippe to pound sand, and date his wife on top of it. There was a goofy obeisance to, you know, authority.

Now, accountants dress in Pound Notes, or Franklins, and call themselves boss.

What utter bull****.

infrequentflyer789

Yes, as an investor, there is a big concern. First, to develop a new engine, certify it, and then put it on the wing of a new aircraft being certified usually involves an investment of $2B US. And then, the first engines are usually sold at a loss as you are not far enough down the learning curve to produce a profit. Then there is the matter of how big the program will be (there is competition), e.g., a large number of engines over a long period of time. And finally there is the matter of the "Total Care" program.

The engine service program (Total Care) is really (should be) the big money maker but it is based on an actuary type system, the expected performance of the engine in the field over a time period before significant servicing, repair or replacement parts are required. These contracts typically are 10 years or more and the amount charged per engine to the airlines doesn't go up much over time to cover the cost of a bad start.

So with the problems at the moment, there is a significant setback of the new engine sales break-even point and the service end of the business is getting hit with costs that were not expected. Both are negatives on the bottom line.

There is always the possibility that when all costs are added up and the program doesn't produce enough profitable sales in the long run, the money lost will never be recovered.

Hi Turbine D
Appears you are one of the resident experts on engines. I understand the FAA's 2007's new ETOPS regulations require ETOPS certification even for four-engine airplanes if they will operate on ETOPS routes. I understand Boeing will be the first manufacturer to certify a four-engine airplane to ETOPS standards when it certifies the 747-8. I also learned from a book I recently read that Australia will require a similar certification for all airplanes including the 747, A380s in a few years. If so, reading your following comment:

Will this looming ETOPS certification further worsen the cost situation? Thanks for your expertise

My old uncle was an elec engineer for WSTNGHSE/GE (dynamo’s/cmcl power) back in the 40’s - 70’s and, my-o-my, the stories, some hilarious, he used to tell about the “bean counters” v/v best engineering. Now, this latest discussion takes me back to his old words as well as reminiscences of my own revolving around an old axiom I sometimes used to hear in mx about aircraft returning to revenue just out of D Check.

Strange how they’d often suffer one or a half-dozen (sometimes big) grounding squawks right out of the box on their first revenue flight. They’d sometimes wind up at some God forsaken downline station where you’d have to send a half dozen guys, fix it or not, or get a waiver and crew together to ferry the thing to a place where it can be repaired.

The moral was something like, “There’s never enough time or money to put it back together and test it right the first time, but, OH, YEAH, there was always plenty of both later on!” Seems this sarcastic rule might be equally at home today within the hallowed halls of RR (or GE/Pratt/Snecma, etc) as well? I like to think not, at least not of the major safety compromising type... but then I think of my old uncle angrily grousing about “beaner” rule in the land of dynamo's.

Why I think maybe even Boeing corporate might be just a little upset with their own beaners now that we’ve witnessed all the "save a buck" international fiascos that have gone on in development and construction of that neat new airplane of theirs. So glad I’m retired! LOL

Unbalanced Rotors CF6-45/50
 

No sooner done with one unbalanced engine we move on to the next..
Recommendations without a MANDATE DIRECTIVE and of serious concern..in other words they can do as they please!

HEADS UP!

CF6-45/50

Note: This will test just how robust this site is to pressure from commercial interests at the expense of OUR Safety

"The first recommendation asks that the FAA require operators of aircraft equipped with a particular model engine to immediately perform blade borescope inspections (BSI) of the high pressure turbine rotor at specific intervals until the current turbine disk can be redesigned and replaced with one that can withstand the unbalance vibration forces from the high pressure rotor. The second recommendation asks the FAA to require the engine manufacturer to immediately redesign the disk. The NTSB issued an additional recommendation for a requirement that operators perform a second type of inspection and another recommendation related to the engine manufacturer regarding the installation of the replacement disk."

Document SB-10-20 May 27 2010. NTSB URGENT

More reading here:
Four Recent Uncontained Engine Failure Events Prompt NTSB to Issue Urgent Safety Recommendations to FAA @ AMTOnline.com Top News

and officail document here
http://www.ntsb.gov/recs/letters/2010/A-10-098-101.pdf

DERG. Only last week you said -

And now?

My life
 

Forget

Profound question yes. I think the better question would be which airplane would I be happy to see my loved ones board. Or indeed any form of transport where I personally have no control over the machinery.

If that journey had to made I would chose which operator, which airline I would trust. There are very few operators which I would avoid. Now you will be asking why the f:mad: does he just not answer the question!

Would I trust the RR T900 as it stands as of now in use with the operators who use it. Yes I would. Would I trust the CF6-45/50 with the operators who use it as of today. No I would not.

As for the T972 in use with Qantas, given the fact that it is replaced..we hope..every 70 cycles and the fact that there are four units on each A388. Yes I would.

What aircraft would I use if I had a free choice for the places my family is most likely to visit? That would be the BAe 146.

70 Cycles between changes and OH ?
I am not sure what documentation you are reading BUT whom is changing engines every 70 cycles.

To mention a BAE146 in regard to reliabilty and safety.
( Bring Another Engine ) 146. :ugh:

Thanks for returning to thread Bolty.

So they are not changing the T972s evey 70 cycles. Right.

Maybe they have changed the "chip" to back to the T970 specs?

As far as the 146 goes, as long as you choose your seat well, I believe it will get you there.

Has the 146 had an uncontained engine failure?

No. Don't think so. The 972 thrust is required for the LAX T/O and as you see the 380 has returned to daily LAX sched.

Can't recall an uncontained failure except for its operational service in OZ. If the engines weren't poisoning the pax with oil fumes they were failing at a rate that paid for engineers homes in the overtime they generated.
If I were to choose my seat well for a "fruit bat" (Oz name for a 146) flight it would be in the terminal waiting for another type aircraft. ( I am probably being overly harsh) :)
Amongst us engineering types the BAE 146 is the only aircraft you have to check the front and back for bird strikes if reported. Boeing 744 is my pick,

Back to Trent failures.
I have a recollection of Cathy grounding its fleet of RR powered A330s.
Something about an angle gearbox failing structurally due to out-sourcing poor quality control in machining.
The CEO of Cathy grounded all its A330s where ever they were in the world as it was unable to predict a life span of the engines as some engines failed at 3000 hours and some close to 50.
This is a vague memory from the 90s but it would appear this type of trouble has struck before.

Very much appreciate your view Bolty. Thanks for rejoining the thread.

Note: A new thread has been started in the Tech Log about the CF6-45/50 URGENT subject.

The relation to the T972 failure is: HARMONIC EXCITATION LEADING TO UNCONTAINED ENGINE FAILURE.

This is the math used
http://www.aerostudents.com/files/vi...Excitation.pdf

My guess is that RR and Schaeffer were not communicating effectively while these numbers were entered into the design specs.

There was one or many breaks in communication within or without RR during the design process. This would suggest that the design itself is inherently flawed OR that the manufacturing process cannot be configured to reproduce the design specifications.

Only one way this can happen: non communication or incompetent management.

Bolty McBolt
 

I believe DERG has quoted press releases that Qantas made earlier this year in connection with an affidavit at a court against RR. Reason beside many other items was the RR - information/recommendation/ mandation what so ever one may call it - that using the T972´s with 540 psi at p30 - as I understand the max. perm. TOP - would make it necessary to change engines - even "mod C " after 75 such cycles.
This information was posted in this thread before and untill now it has not come to public that this restriction was lifted.

So if you write that QF flies daily A 380 service to LAX that either implicates that these flight are narrowly controlled and after 75 cycles the mentioned engine change silently takes place, or there is another modification made on that engine - probably called "mod D" - that has eliminated the concerns that led RR to issue such a severe restriction.

Never the less in my opinion you`re sounding very confident - overconfident may be ?? - having in mind the fact that the spline AD is still valid and even the newest engines must be inspected after 200 cycles and follow on at 100 cycles. (s.a. EASA AD-No: 2010-0242 R1)

Could it be that the members of this net simply have missed an important change in regulatory paperwork for the daily usage of the RR T972 ??

Hi avgenie,

Having read through the new ETOPs plan for 3 or 4 engine aircraft, it seems to me that most of the responsibilities will be on the operators (airlines) that fly these long over water routes. Route planning and diversion planning becomes a more demanding issue than what it has been. I don't see it as a big cost item for an engine manufacturer unless there are unforseen problems that develop in revenue service.

For new aircraft/engine combinations, ETOPs is generally applied for and demonstrated during the certification phase. Since most airlines establish contracts for the aircraft and engines separately, I would bet there will be penalty clauses established should either fall short and the contracted ETOPs rating is not achieved or becomes reduced because of problems. This is where the bottom-line of either manufacturer could be impacted depending who has the problem and how long it takes to resolve it.

There is another large customer today, leasing companies. They buy airplanes and engines and lease them to various airline. Since these deals are very complex and vary considerably it is hard to tell how this change will affect them.

Forgive me for repeating this post I made in the other thread on 3 December.

Believe me my question is NOT intended in any way to provoke any sort of argument because I am totally ill equipped to have an argument with anyone . But I do wonder sometimes if Rolls Royce make aero engines these days or just assemble them --they seem to buy in bits from all over the world. Does this strain quality control?
When I was a kid the impression was that they made everything -even all nuts and bolts--from alloys they made themselves in their own foundries. They had, it seemed, total control.

Who made the apparently crude oil pipe for them?

As I read the unfolding story on this thread this question of mine nags at me more and more. Is there inherent danger in buying in parts from all over the world instead of making them yourself?

And please can I ask another question?

Why do RR need so many different engines? It seems like every new plane has to have its own engine type. Someone on this or the other thread has already asked why RR do not replace the 900 on the A380 with two pairs of different proven reliable engines to give the same thrust.
Same as before I am not trying to stir anything at all. I am just SLF whose father worked at RR for 40 years in Experimental Dept at Sinfin.

Flapping_madly

You ask good questions, no apologies required.

I think the total vertical integration business model dates back to the start of mass production automobile manufacturing. In the US, Henry Ford had and made everything required to produce a car or truck in his own factory.

The same was true during the war years, both in the US and in the UK n the manufacture of aircraft engines. However, with the advent of the jet engine and the globalization or reach of businesses, the vertical model began to fall away. One reason might be specialization where smaller external companies invested both in technology and manufacturing capability to produce certain items of good quality and lower costs than what could be manufactured in-house. Larger companies were tempted to go outside for items as it saved financial resources that would be required to update equipment and manufacturing processes to remain cost competitive. In the end, only the most highly technical items and processes remain in-house. The less technical items can be purchased outside satisfactorily with good quality oversight and planning. Today, this has spread globally as business deals are made to sell product while some of the product content is made in the buyer's country. It does require a good quality organization worldwide and sometimes, on site daily depending on the product being produced. It is also important to have a good technical capability plan and assessment team in place to assure capability before orders are placed. So, yes, Rolls Royce, GE, Pratt & Whitney and others have become more focused on design and assembly of engines and less involved in actual parts manufacturing. The key to success is not skimping on quality oversight no matter where parts are produced.

I will answer the engine question in another post.

I don't know the answer to who produced the stub pipe, but I understand the latest engine revision doesn't have the stub pipe component at all.

My experience has and is in the "suck-squeeze-bang-blow" engines(in other words Diesels)
Compared to diesel engines, the gas turbine manufacturers are pretty much "in-house" when it comes to self sufficiency in component manufacturing.
Of course there are outside specialist suppliers, but compared to my industry they do pretty well.
Only about 30-40% of a diesel engine is manufactured by the brand name.
Pistons,bearings,valves, fuel injectors, governors, turbo-chargers, coolers and so-on are all sourced from specialist suppliers.

Raw forgings come from specialty shops; configuration plumbing and valves etc. likewise. GE bought fuel controls for some engines from Hamilton Standard, then part of United Technologies, a major competitor (think P&W).

But sometimes the engine builder buys the supplier's business, in order to exercise more control.

Doesn't matter where the bits are made. It is the Goods Inwards Inspection that accepts or rejects all parts.

Barit1, you are correct, some very critical components are bought from speciality suppliers, forgings, from which discs, casings and engine mounts are machined from, investment castings from which structural components and turbine airfoils are produced and no doubt a few other more critical components from other processes. At one time, all three engine manufacturers had investment casting foundries, but I think only Rolls Royce has a production facility today.

There has been some purchases of independent suppliers by the engine manufacturers where the technology knowhow meshes well with the technology thrust of the engine company, such as composites for example.

The spline wear, fretting, increases exponentially with time. The broken oil feed pipe did us a favour and we were lucky. I am sad the CEO of RR is leaving in March. He has been a good man. I remember well the events of 1971..in the early part of February that year a few of us in the sixth form thought the shares of RR would be a "good thing to buy"

Supplies, supplies...
 

Barit 1,

for what it's worth the Trent 900 engine control is also made by Hamilton Standard but the software is done pretty much in house.

good news
 

Just found this on the FlightGlobal site. I think that is really good news!!
Qantas's damaged A380 to return to service this year

Bolty McBolt
 

That is the article I referred to in my previous message:
High thrust Trent 900s limited to 75 flight cycles: Qantas

Thanks to Turbine D that did the search and digging for the right link.

Someone can't add up
 

"Joyce says the cost to repair VH-OQA, the first A380 delivered to Qantas, will exceed A$100m (US$99.8m). Insurance and contractual agreements with Rolls-Royce will cover the repairs. Qantas says A380 disruptions had a $55m cost impact in the first half of its financial year ended 31 December. The carrier estimates a further $25m impact in the second half of the year.":confused:

These numbers differ significantly from the cost as estimated in the official statement by RR. Looks like the Bayesian Academics have migrated to the accounts department, probably the only place where they feel safe.:E

Looking ahead to the end of March, the new CEO John Rishton will replace Sir John Rose. Both these men were social science graduates and there is no guarantee that John Rishton will keep the Bayesians where they belong: on the staff of THE RACING POST.:suspect:

I remember Feb 1971 well enough:

"The RB211 demanded a huge step in technology within a very short timescale a double challenge for which Rolls-Royce was ill-prepared," Sir Ralph Robins, the former Rolls chief executive, said in its centenary lecture in 2005. "One very important lesson emerged from the early problems with this engine the fact that major, new, advanced engine programmes can only be successful if they are well-founded on previously demonstrated technologies. That, sadly, was far from the case at the start of the RB211 programme."

Note well: "previously demonstrated technology"
viz. Newtonian mechanics..been around since 1680CE
as taught to 16 year old sea cadets:

http://compass.seacadets.org/pdf/nrtc/fn/14104_ch6.pdf

.

VnV2178B

With respect, the Controls systems are built by Hamilton Sundstrand, not Standard.
They are a division of UTC.

The "Oil Stub Pipe" was built by Rolls Royce.

Hamilton Sundstrand pitches themselves as "Tip To Tail" supplier for the A380.

DEP

For my "U" boat friend.

This Plug is located on the top of the Channel "B" module of the EEC. It is restrained by a "Lanyard" attached to the Engine's Fancase.
The DEP is purpose built to contain Data individualized for the specific powerplant to which it is attached. It is a Plug and Housing that contains a dual channel memory device called EEPROMS. One each is dedicated to a Channel of the EEC.

Each EEPROM has identical Data, to wit:

The Engine Serial Number, The Engine Ratings Selection, The TPR and THRUST TRIM Relationship, EGT TRIM, and Idle Trim.

The EEC, as you know, is programmed with ALL Engine Ratings. The DEP discrete DATA allows the EEC to select from its memory the applicable ratings for the aircraft in question.

TPR TRIM is adduced in engine test to report to the aircraft whilst in flight identical data for all engines across the wing. It obviously calibrates Engine Thrust (TRIM) tailored to the other engines on the wing as well. The DEP, then, is responsible for commanding identical settings from each engine on cockpit selections.

EGT TRIM is commanded from DATA programmed during Rolls Royce type test.
This limits EGT to pre-Programmed values, aligned with Cockpit reads.

IDLE TRIM is managed by the EEC, whether minimum or Approach, and it is The DEP that controls EEC's control limits.

EEPROM. Electrically Erasable Programmable Read Only Memory

You are right, it is Sunstrand - I am just too old and still think of them as Standard!

My interest - I was involved in the FADEC software.

Aah......"Authority issues then...." :ok:

RB211 "early problems"
 

Sorry - the machine had a bit of a wobbly, so I forgot the Post No. (short term memory on the blink).
Ref early RB211 problems: I think RR's chief was referring to the company's rush to carbon fibre fan blades which caused vast embarrassment when sandy environments (which don't exist in Derby or Barnoldswick) caused unexpected erosion. While Lockheed had been urging a titanium back-up, inventing the sophisticated vacuum forging/diffusion bonding process to get weight down took lots of time ... as did the company's subsequent bankruptcy and nationalisation.
I don't think the 3-shaft layout was the cause - apart from needing a light-weight fan to keep the overall weight down.

Years later, GE, for the "90", did the CFRP thing right, if course ...

Aren't GE using CFRP/Titanium Fan Blades?

I thought the main problem with the carbon-fibre fan was that it did not pass the bird impact tests?

To Bearfoil & Ken Parry
 

1) I woz wrong about sand - bird-strikes it was indeed: memory again ..

2) I think the GE solution is CFRP with titanium leading edges to do the right thing with birds ...

Here is a report I found (pdf.file) that gives some status and information on the composite GE90 fan blades. They are doing quite well, more current data indicates only 17 fan blades have required removal from service for repairs, mainly bird strike incidents.

http://www.niar.wichita.edu/NIARWork...id=110&mid=599 -

They had their own problems with the "grandfathered" CFM-56 on the 737-400 though (viz. Kegworth).

Note 'current data' is may 2007, lot more GE 90-115's in service now. Tips were cropped a few years ago due to rubbing issues, thereby losing some efficiency. To be expected when you look at physical size of engine. Changed 4 in one hit due to fod damage a couple of years ago . Very expensive according to paperwork , but cant remember figure.

Qantas's damaged A380 to return to service this year