QANTAS A380 Uncontained failure.

[chase888]

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.

[barit1]

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.

[mike-wsm]

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

[Turbine D]

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.

[DERG]

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"

[VnV2178B]

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.

[Annex14]

Just found this on the FlightGlobal site. I think that is really good news!!
Qantas's damaged A380 to return to service this year (http://www.flightglobal.com/articles/2011/02/17/353293/qantass-damaged-a380-to-return-to-service-this-year.html)

[Annex14]

That is the article I referred to in my previous message:
High thrust Trent 900s limited to 75 flight cycles: Qantas (http://www.flightglobal.com/articles/2010/12/14/350901/high-thrust-trent-900s-limited-to-75-flight-cycles.html)

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

[DERG]

"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

.

[bearfoil]

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

[VnV2178B]

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.

[bearfoil]

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

[Jig Peter]

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 ...

[bearfoil]

Aren't GE using CFRP/Titanium Fan Blades?

[kenparry]

when sandy environments (which don't exist in Derby or Barnoldswick) caused unexpected erosion

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

[Jig Peter]

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 ...

[Turbine D]

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/NIARWorkshops/LinkClick.aspx?fileticket=A9ZP0isO8Q4%3D&tabid=110&mid=599 -

[DozyWannabe]

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

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

[bvcu]

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.

[kappa]

Qantas's damaged A380 to return to service this year (http://www.flightglobal.com/articles/2011/02/17/353293/qantass-damaged-a380-to-return-to-service-this-year.html)

[Turbine D]

DozyWannabe

Although a fan blade broke on this engine, it was actually the stage 1 LP compressor blade that was the problem:

Analysis of the engine from the crash determined that the fan blades (LP Stage 1 compressor) of the uprated CFM56 engine used on the 737-400 were subject to abnormal amounts of vibration when operating at high power settings above 25,000 feet (7,600 m). As it was an upgrade to an existing engine, in-flight testing was not mandatory, and the engine had only been tested in the laboratory. Upon this discovery all 99 Boeing 737-400s (since G-OBME had crashed) were grounded and the engines modified. Following the crash, it is now mandatory to test all newly designed and significantly redesigned turbofan engines under representative flight conditions.
This unnoticed vibration created excessive metal fatigue in the fan blades, and on G-OBME this caused one of the fan blades to break off. This damaged the engine terminally and also upset its delicate balance, causing a reduction in power and an increase in vibration. The autothrottle attempted to compensate for this by increasing the fuel flow to the engine, however the damaged engine was unable to burn all the additional fuel, with much of it igniting in the exhaust flow, creating a large trail of flame behind the engine.

[Bolty McBolt]

For Qantas to abide by Rolls-Royce's derated take-off thrust guidelines, A380 flights LAX would carry only 80 passengers due to payload restrictions.

Thanks annex14 for the read

Ok flights are full i.e. 60 t payload. All engines are "C" build and flights will be twice a day in the near future as it was prior to the incident

If you look at the date of print, mid December. It was an eternity ago in this saga as I don’t think many staff involved in the T900 project had any leave over Christmas. There has been much correspondence between the 2 companies (RR & QF ) since.
RR has blessed a list of QF engines capable to do the flights at thrust ratings required.
If the 75 cycles rule with 2 LAX departures a day is applied to QF with a fleet of 9 it would need to re-engine in a little over 330 days. With the current availability of 5 LAX approved aircraft a re-engine would be required in 190 days. 20 engines after 190 days flying ??
. RR cannot make engines or modules quick enough to cope with this demand.

Some pruners mention the IP coupling. Yes it is inspected for wear every 100 cycles.
Has anyone changed an engine yet due to coupling wear? Probably not ,due to the new engine builds being compulsory fitted but RR now has dozens of engines to draw data from regarding the wear. I guess we shall see which part RR redesign first?

[bearfoil]

Hiya. Actually there was an engine change due Spline wear, but the Brass at RR call it an oil fire, not specifically Spline Smoothies. #2. QF32.

Given what's known, and your perspective, it is at least a good guess that RR have mitigated the cause of Spline damage by acceding to Inspections, as to my way of thinking, they are eating canal mud on LAX SYD.

No, not really. They have mitigated the focus on the actual problem by eating a swap/strip/rebuild at an agreed interval. This interval is Qantas' schedule, and EASA/ATSB mandates, with input by RR. Most expensive, but the alternative is a re-design to eliminate Resonance discovered in 972 test, but ignored because it was a "family tradition" to mimic previous test and banked approvals via certificates in the dusty files.

Who throws in the towel first?? I think RR will keep eating. They cannot retool and recertify, and "Continued Airworthiness" via a Permanent AD is too, what, Public??

There is precedent for engine swaps, Bolty, dozens of them. The Firm dog chewed a relaxed inspection interval by convincing EASA that the Splines would be "just as well" investigated with "averaged" crest wear at abutments instead of a mandated strip search at "worst case wear" involving but one Spline per Coupling set. This is in the Public AD divulgences, and speaks volumes.

Oil is hot because the engine is light, floppy, and viscous deficient with time in case of approved oils. The FOHE also does a crap job of cooling the oil when Fuel is Warm, just after launch, just as it does a crap job of heating Fuel when the engine is cold soaked, and the Oil is cold soaked, (At Altitude, or long CDA) or missing, due bypass to Air cooled Route in the Oil Path. It's all in there, and the Splines are complicit, but only as the canaries, just as the Bearings, Oil Tubes, and Oil system are likewise.

[Old Engineer]

That is a very interesting set of comments. I've been intending to put up some information about splines, spline design matters, and my thoughts on vibration related to splines. I just wanted to find an example that backed up those thoughts, and I found it a couple of days ago. It was a 7th harmonic vibration in the particular example. A high harmonic is what I was thinking. As hard for me to find such a report as it was for them to find the 7th harmonic.

Looks like you have decoded the recent reports on Qantas actions and comments. I read a set of several over on Flight Global this afternoon. Apparently we both now believe that every 75 take-offs from LAX four engines are going to be scrapped (or very substantially rebuilt?). So this will have to take place back at the real factory, not at the two special RR-900 qualified shops out in the field, no?

[bearfoil]

Eureka. EASA cannot allow averaged wear format any longer, and must revert to single case (5mm crest) strip. No one strips an engine and then does not replace parts on reassembly. The Parts? Every Spline has a sister, and that means both stub Shafts of IP and LP modules. If there is an upgrade in any thing pertinent to the AD, the FAA will get a smell, and that means everyone will know. Let's get further into the strip and r/r. All rotating mass will be affected by the resonant's dirty work, so who calls the replacement relative to time in service, wear gross clearances, and risk/benefit verse Capital outlay?? His is a very pivotal role. Bearings, Splines, Labyrinthines, Carbon residue in the FOHE, vent pipes, clean? replace? Will the Magnetic chip sensors tell a tale? Oil Pump (both) plus scavenge pumps, filters?? To get the eight modules apart, and then not rebuild sufficiently means doing it again with off wing and replace with new engine or park the Whale? How long? The numbers quoted as costs to Rolls are ridiculously low. Qantas will not pursue their suit (and give up those nuts in the vise??) Haste makes waste. IMO

Disclosure and honesty are the shortcut to healing all mistakes. The other way is exhaustive, expensive, and potentially lethal. Collective Pride.

[DERG]

I have seen a report where one of the Qantas T972s had metal chips on the magnet trap SEE BELOW Glad OE has posted!

This is the type of metal trap we are talking about
Vibro-Meter Magnetic Chip Detectors and Chip Collectors (http://www.vibro-meter.com/aerospace/mag-chip.html)

In fact the 900 series is the first to have a chip detector that sends messages back to base. It is detailed, along with the other sensors on the engine here..
http://www.ingenia.org.uk/ingenia/issues/issue39/Waters.pdf

and moreover
Ingenia Articles (http://www.ingenia.org.uk/ingenia/articles.aspx?Index=552)

Qantas A380 engine had problems before explosion
6.12.2010 (Sydney Morning Herald)

It's been revealed that the engine that disintegrated on a Qantas Airbus A380 near Singapore last month had earlier been taken off the aircraft to fix another problem.

The Australian newspaper says investigators have revealed that the engine was only refitted in February.

An Australian Transport Safety Bureau report released last week shows the No 2 engine was originally fitted as the aircraft's No 4 engine but was removed last year after metal was found in a chip detector.

Chip detectors are often a permanent magnet used to gather metal fragments, usually from lubrication oil.

The relatively new engine had performed just 3419 flight hours and 416 landing and take-off cycles at the time.

The engine was sent to a Singapore workshop certified to maintain and repair Rolls-Royce engines in September last year.

Engineers found spalling in a low-pressure compressor bearing and replaced the bearing assembly. Spalling occurs when flakes break off from a larger component and is usually associated in mechanical systems with high-stress points.

The low-pressure compressor is a different part of the engine than the one that failed in the dramatic Singapore incident.

The repair was completed in December last year. The engine was fitted to the aircraft on February 24 and had completed a further 2895 flights.

[bearfoil]

There is a Vickers Electric Master Chip Detector, which is installed at the combined scavenge return inlets (At the entrance to the Scavenge Filter), and nine Muirhead Vatric screw in Detectors at the inlet of each of:

Front Bearing Housing
Internal Gearbox (HP Rotor)
Internal Gearbox (Rear)
HP Turbine Bearing Chamber
IP Turbine Bearing Chamber
LP Turbine Bearing Chamber
Intermediate and Lower Bevel Gearboxes
External Gearbox
Centrifugal Breather

Ferrous metal is entrapped and conducts electricity across two poles in the detector.
If chips are in the Master, a specific screw in can be checked to ID the type of metal and from whence it came from the nine locations from the scavenge. Bits in Oil are of course, not good.

DERG

Are you referring to an ACARS prompt? Or a Total Care Alert at Derby?? Because the Vickers Electric Master Chip Detector sends a message to the cockpit, but ten minutes after landing. Metal in the master is what alerts the install of magnet probes by Mx to install smaller detectors (The Muirheads) in the nine scavenge ports before next flight, since normal operation of this engine (T9), has the Vickers only installed. Each smaller unit allows for narrowing down the location of the disintegrating part.

[DERG]

BEAR I don't know

this might tell us
Ingenia Articles (http://www.ingenia.org.uk/ingenia/articles.aspx?Index=552)

[bearfoil]

I'm using the Engine Manual. (TRENT 900) The manual is specific as to manufacturer of the Oil Debris sensing kit. Specifically, the Master Chip Detector is Electric, it uses a current of electricity to find ferrous bits in the detector (It is not a permanent magnet). The Vickers 'Electric' Master Chip Detector. The Muirhead Vatric Screw in Chip detectors are permanent magnet type units.

The replacement of the Bearing in the LP Compressor was discussed by Old Engineer some time back. I think it was determined that replacing the bearing was a good thing, but did not (rather obviously) solve the main problem, the Harmonic, which caused the bearing to fail in the first place. RR is back into replacing parts rather than admit the true problem and have to either scrap or redesign and re-certificate the 900.

[DERG]

In the ATSB prelim report there are pics of the graph plots of engine parameters. One of them is labelled "Oil Chemistry". If that includes a value for solid debris I do not know. Does anyone know please?

[bearfoil]

You're losing me, DERG. Solid metal bits does not sound like it obtains to Oil Chemistry. IMO. Night.

[DERG]

Agreed Bear. But after this event anything is possible!:\

THE MORAL ISSUE

The fact that people on the ground know more about the engines than the crew on the aircraft is UNBELIEVABLE.

The fact that this aircraft was designed for long distance oceanic and transcontinental routes inherently means that any communication system that relies on standard HF and VHF communications is flawed.

The Bayesians have been used to provide Rolls Royce with a cost monitoring tool with no regard to life and limb at the critical time.

This is the issue here. All the documents are focussed on $$$$ reduction.
Not safety.

What part did Sir John Rose play in this?

He saw exactly what was happening and decided he wanted no part of it.
It is one thing to use statistical methods for cost prediction but quite another to play the deity with the public. He left the company.

Good for him.

[Turbine D]

Here is the history of the #2 engine prior to failure from the ASTB report:

he No 2 engine was originally fitted to the aircraft in the No 4 engine position during aircraft manufacture, and was removed from the aircraft on 12 August 2009 due to metal being found on one of the engine’s chip detectors.16 That removal took place after 3,419 flight hours and 416 cycles.
In September 2009, the engine was sent to a workshop in Singapore for examination and repair. That workshop was certified to maintain and repair Rolls-Royce plc engines. Spalling of the top raceway of the low pressure compressor location bearing was identified and the bearing assembly was replaced. The repair was completed in December 2009.
The engine remained in storage until it was refitted to the aircraft as the No 2 engine on 24 February 2010. The engine had completed 2,895 flight hours and 261 cycles since that re-installation.
On 24 June 2010, Rolls-Royce plc Service Bulletin RB211-72-AG329: IP Shaft Rigid Coupling - borescope inspection of the coupling splines was carried out on the engine. That inspection was mandated by EASA AD 2010-0008 dated 15 January 2010, which was subsequently revised by EASA as AD 2010-0008R1 on 4 August 2010.

Take a look at the engine parameter chart again, you may want to print it out to see it better. The bottom graph is title "oil quantity", not "oil chemistry".

IMO, I think it more important for the ground mechanics to know that metal has been detected in the oil after each flight, or not, as is the setup on the A-380's. Chip detectors are there to signal the existance of wear in one or more of the bearings and it is up to the ground personnel to investigate and locate the source, not the flight deck crew. Think about it.

[bearfoil]

DERG

The Executive executes, he/she implements, enforces, and Leads. The Leadership may be Blessed, or not, and 'one monkey don't stop no Circus'.

Politics has as its main objective to distract, to Puff, to Bamboozle. Corporate Politics are no different. There is more Cachet than Cash, Eh? Personnel are interchangeable at the highest levels. The Board is the secret to navigation of troubled waters, and firing or resigning are popular arrows in the group's quiver.

Stock Price, Brochures, and Numbers. Engineering has become a supporting player.

Now that "Q" has passed, Rolls is at the mercy of Three Piece jackals who understand more about Money and Illusion than Oil and its Perfusion.

Turbine D

Thanks, very much, Sir. Cockpit alert for metal bits is as you say, "Huh"??
ACARS is the venue for maintenance, and even Total Care takes a minute to find out the good/bad news. If the ECAM shows metal in the Vickers, (Ten Minutes after wheels on), the mechanics start to decowl and place the Muirhead Vatric Magnets in Place, to narrow down the Trail. The a/c takes off again, next landing Sherlock and Watson get to work. Each magnet plug has a check valve so as to not spill oil in removal, the plot was well thought out in the first place. It is not so desperate as it sounds.

Correction?? I think there was a September amendment which allowed Rolls to average wear of the Splines as a Coupling UNIT instead of Strip if ONE Spline was found with minimum Crest Metal. The "Crest" had 2.65 mm of showing metal at its crest on assembly, and EASA and Rolls determined .5 mm was bad enough to warrant an off wing strip and "replacement". Later (September) Rolls was excused from the "hardship" of strip in favor of a more lax regimen wherein all Splines were measured, and strip was commanded if the "average" wear was .5 mm. Then comes November 4th, 2010, etc. etc.


just sayin'

[DERG]

Turnbine D Yes thanks I see now, my eyes have seen better days.

Bear That does not stop us seeking the truth though.

Heads up..here we go again: another oil loss and anther loose oil coupling.

NEW ENGINE EVENT IN FLIGHT ON FEB 15 2011

Investigation: AO-2011-026 - Partial power loss - Airbus, VH-OQC, near New Delhi International Airport, 15 February 2011 (http://atsb.gov.au/publications/investigation_reports/2011/aair/ao-2011-026.aspx)

and
Qantas A380 finishes London flight on three engines – Plane Talking (http://blogs.crikey.com.au/planetalking/2011/02/18/qantas-a380-finishes-london-flight-on-three-engines/#comments)

"According to Qantas the issue that affected the engine has also been found on a Rolls-Royce powered A380 flown by another airline (meaning either with Singapore Airlines or Lufthansa) and it is one which has been raised with the engine maker and is neither the same nor as serious as the issue which saw the disintegration of an engine on QF32 shortly after leaving Singapore on November 4."

Quote from ATSB "During the cruise the crew observed a gradual decrease in the oil quantity for the number 4 engine. As a precaution the engine was reduced to idle for the remainder of the flight.
A subsequent engineering inspection found that the fitting of the external HP/IP oil line had less than the required torque. The investigation is continuing."

My thanks to a colleague on Australian Thread on this site poster"TBM-Legend"

[Flapping_Madly]

All I am is SLF. That's all. (That's all ?!?!? Well I'm damned important to me and my family !!)
So I don't know much about all this. Except it worries me quite a bit. When I board a plane I think I am entitled to expect the engines will stay in one piece. Usually they do. Maybe this Qantas debacle is a total oddity. But some of the stuff being unearthed by the incredibly clever people on here gives cause for concern. The more I read the worse it gets.

I would like to think that when something as immensely important as an airliner engine is designed and built everyone involved is issued with a list of "bear these firmly in mind in this order" reminders.
Reliability
Robustness
Dependability
Serviceability
Inspectability
Dismantleability
Repairability
Monitorability
Controlability
Transportability
blah blah blah and ending with
Minimum fuel burn
Minimum weight
Minimum cost.

Having built the engine pop it on the scales to see what it weighs, screw it to a wing and see if it works and how much it drinks. And those numbers get written on the box lid. Bobs your uncle.

Perhaps with the 900 they had the list upside down and built a flimsy under-strength flexible wobbler that wore out too quickly and shook itself to bits. Shortly they'll be inspecting the things so often they'll never take off.

And my unhappiness with only two engines over oceans instead of four has gone up a ratchet or four.

Don't SHOUT at me I'm only SLF. I'm entitled to my worries.:uhoh::eek:

[DERG]

Hell YES Flapping Madly your views are welcome and valid. What you posted in the vernacular is what most of us are thinking.

TURBINE D

Can you think of the last time a licensed engineer did not tighten up an oil joint properly?

You think his mobile 'phone went off and distracted him? I am REALLY struggling with this excuse.

Seriously...an oil coupling on a unit that already has a history of oil pipe issues?

Look at this flight level...

A Qantas Airbus A380-800, registration VH-OQC performing flight QF-31 from Singapore (Singapore) to London Heathrow,EN (UK), was enroute near Delhi (India) when the crew noticed that the oil quantity of engine #4 (Trent 972, outboard right hand) gradually decreased. The crew continued to London crossing the European Airspace until 125nm eastnortheast of London at FL380 and landed safely on London's runway 09R.

The airplane subsequently remained on the ground in London, the return flight QF-32 was performed by VH-OQG instead. VH-OQC was able to depart for its next flight QF-10 about 18 hours after arrival in London.

The Australian Transportation Safety Board (ATSB) reported that following the landing an engineering inspection revealed "that the fitting of the external HP/IP oil line had less than the required torque". The engine power was reduced to idle at some stage of the cruise for the remainder of the flight.

Radar data show the aircraft passed Moscow (Russia) at FL381 (11600 meters) about 3 hours prior to landing, descended to FL380 upon reaching Latvia and continued until a point 125nm eastnortheast of London at FL380 before beginning the descent into London.
Source: Aviation Herald

"The engine power was reduced to idle at some stage of the cruise for the remainder of the flight."

At 38k feet with one on idle? Light load? Other three on 97% throttle?

[bearfoil]

Insufficient Torque. Fancy that. A 972 with loose bits about. The very same Stub Pipe, then. Someone in Derby is in serious Denial, or worse. Nothing to see here, move along. Please put the KoolAde down. Does any one continue to doubt this powerplant shakes itself to the Danger Zone?

It is a big engine, and carries twenty eight quarts of OIL. Total, per engine.

Time.

The needle and the digital indicator are normally GREEN. When the EEC senses FOUR QUARTS LEFT, the signal on ECAM PULSES.

The largest Three engine Airliner in the world, ever. Sorry 411A. TRITOPS??

[DERG]

Bear When this hassle began, and Qantas punted the A388 out of Europe toward the Far East, it often returned back to London with some issue or other. They decided to continue to London in this case too.. At first I thought the Aussies were xenophobic, but I just read a comment over on another website that adds up. You know there are not a lot of airports that can handle this size of aircraft. Then what do you do with 470 passengers say in Dnyepetrovsk when the hotels only hold 200?

Then of course there is the $50k plus hotel bill!

Rock On!:cool:

[PickyPerkins]

If an engine has a vibration problem, and it is found that


"... the fitting of the external HP/IP oil line had less than the required torque ..."


does it necessarily follow that


"... a licensed engineer did not tighten up an oil joint properly ..."


Just wondering.

[gas path]

In fact the 900 series is the first to have a chip detector that sends messages back to base. It is detailed, along with the other sensors on the engine here..

Er. Rubbish! So does the GE90 and has done since the beginning! It has also saved a few inflight shutdowns too, enabling a timely removal.
Mind you the last one I had had so much debris on it the chip counter couldn't add it all up!

[bearfoil]

picky perkins

Any admission of a "Vibration Problem" opens up a double container (Maersk Line) of Worms, obviously. No vibration (unaddressed) can be called a "Novelty".

A Pint says the chap who ticked the Box at 48 ft/lbs. will swear he did, and another Pint says He will not even be Interviewed, not even by RR (Plausible Deniability).

What of the Bench Monkey who belched whilst counterboring that horrid Pipe??

Same tick, different box. No Interview.

just sayin'

Curioser and Curioser.

[Turbine D]

When a oil tube joint is found loose, it would be natural to assume it wasn't tightened properly during original assembly by the assembly mechanic. That is the obvious and it could be true. It may not have been that it was the assembly mechanic, not tightening it to specification, perhaps his torque wrench was out of order, so the wrench was the culprit. But the history of this particular engine is not be so clear to us. The engine was originally assembled sometime in 2008, so it probably was a Mod A. So during its life, so far, it was probably disassembled and reassembled at least once and maybe twice in going from Mod A to Mod C. But then again, maybe this particular joint wasn't involved during these changes. But then again, there is the not so obvious.

Could it be possible that as a result of making the changes from A to C, a vibration problem (noted in QF32's stub pipe failure, at least partially due to fatigue instigated by vibration) has moved up stream, so to speak? In simple terms, is vibration still affecting an oil supply line to bearings at this engine location, only now on the outside of the engine? Did a properly torqued oil line connection vibrate loose over a period of time? A real possiblility, we will have to wait to see.

[DERG]

This gets more fun as it goes along. Turbine D that was a fabulous answer!:} Thank you!

Now the only question I have is just how they were able to manitain level at 38k feet on three engines. Anybody?:confused:

This saga is becoming more like a Walt Disney Cartoon everyday.

Somebody should hire these Bayesian people as a circus act. Better still we could have a Jerry Springer special. Airbus vs. The Rest.

Me and you Bear would be security..hahah:E

[Turbine D]

You put together a good list of attributes for a jet engine. Just have to add, check the bolts and fittings twice for proper torque and I think you got it!:)

Then there is the matter of ratcheting up or ratcheting down. As I type this to you at 8:20 PM US EST, here is a partial listing of the airplanes flying this evening in the world:

332 B-737-800
322 B-737-700
293 A-320
274 B-757
232 B-777
213 A-319
171 B-747-400
160 B-767-300
139 CRJ-100
139 ERJ-145
120 CRJ-200
119 B737-300
71 A-340

And the list goes on to include freighters, other commuter jets and biz jets.

And finally,

9 A-380

So if you take out the B-747's and the A-340's (and the nine A-380's), the world flies on two engine aircraft very successfully. So, I would not ratchet up 4 but down 4. ;)

As a matter of interest, think of all the fuel being used at the moment, and tomorrow, day or night it will be the same.

[DERG]

This problem is less complicated than we thought.

What we need are MORE vibration sensors. Then we need the soft and hard ware to filter them. Then we need more satellite links to tell the folks on the ground.

The crew do not need to know about nasty bits in the oil so that idea is out the window. They have enough to do as it is.

No..we need another two may be three sensors in the key places. We could then give the Bayesians more data to make better betting conclusions.

Really the cost of adding more sensors is negligable compared to the cost of ignorance. So our pals in accounts can sleep well knowing that the extra few pennies spent...and believe it is pennies...will return a very handsome plus on the warranty costs.

Go forth with this idea and prosper RR we wish you well :)

[bearfoil]

Not too sure about peppering the case with additional Vibe Transducers. Ninety Nine percent of all vibrations produced by this powerplant are known, and catalogued. Even the one percent is not the problem. The problem is a specific and transient Resonant. There is a reason the problems eventuate at specific Thrust, AoA, and Temperatures.

I brought this up on the BA038 thread, relative to fluids Stall at TOGA chat. I also injected it early on in this thread, (Actually the original). The FOHE is a candidate for failure both in cooling/heating capabilities due its position on the Fan Case. Here, the unidentified (though known) Harmonic wreaks its damage in a trail of Wear to all parts in the Core. The OIL Stub Pipe, the Frames, the Fasteners, the Shafts, the Discs, and the Blades. There was an AD for HP airfoil cracking in 2007 for this engine, and no critical part is immune. A reduction (or increase) in Thrust demand might lessen its effect, but will not eliminate it, save in Operational Profiles only.

By the time a Vibration Transducer causes the EEC to relax its demands, the event is merely the last in an increasingly alarming trail of chronic wear. The answer is not even to identify this transient, (this has been done), but to eliminate its cause. This means that an otherwise perfectly serviceable powerplant has a fatal flaw, a self sabotage that needs a re-design. IMHO.

[Flapping_Madly]

Why don't RR just start whistling tunelessly while staring into the distance in a distracted manner and deny all knowledge of the 900 which looks like it will cost them a fortune in constant running repairs or litigation.

"Trent 900 ? what's that then? Not one of ours"
"Yes it damn well is it's on the A380"
"Nah can't be. It's two 800s on the outside ends and two 1000s as inners innit?"
"Yes it is now but the A380 started with the 900 and one blew up"
"Don't recall that and it won't be in the official history"

Are the other engines that RR make not capable of being slung on the A380?
Or would the cost to the airline be about the same as fitting GE engines?

Car makers used to produce the occasional lemon (before computers came along) so maybe this is an RR lemon.

In the opinion of the learned gentlemen on here is the engine fundamentally flawed for some reason that other Trents are free from or are the modifications really going to sort it once and for all?

I thought these things were tested to the nth degree before they entered service not after. :(

[bearfoil]

Well, may as well earn some revenue whilst exploring the "nth degree".

Let's close the circle. Resonance can float a massive Shaft making tens of thousands of Horsepower. Can it "Freeze" (Fluid Stall) a few kilograms of Fuel in the FOHE by virtue of the device's location adjacent this Massive Resonance Maker, otherwise known as the Fan?? I say Yes, and cause synchronous Cavitation in both Engine's Mechanical Pumps as well?? Again, Yes.

Boeing, RR, and the FAA (via NTSB) were unable to produce water Ice in Fuel replicating the vaunted "Fuel Ice" problem of The TRENT 700 in BA and NorthwestAL incidents/accidents. A fuel Path is no less a Shaft than a Steel one. Can Resonant energy "suspend" a Fuel "PLUG" in transit?? Again, I say yes. The AD was to cut down the protrusions of the tubes, ex-tubesheet. However, also commanded were reductions in Thrust to ostensibly "Melt the Ice Plug". Wait, the Engines ran at reduced Thrust after the Cavitation. Right, the Pumps were Toast, and what allowed the Power was Gravity Feed. There was that "Knocking" sound heard by Pax as well. Was that the noise of liberated Fuel Lines rapping on the case??

Funny how a reduction in Thrust also terminates the Resonant.........

I'd like to suggest a newer way to entertain the TRENT problems. Rather than isolating each problem from the Whole, (As in shifting Thread to Spotter's), the best way is to consider the TRENT as "Family", and the problems as siblings, not some easy to marginalize "lone Wolf" that can be marginalized by RR and its puppies into irrelevance.

dons Kevlar

[mm43]

The "nth degree" reveals itself, not when you are looking for it, but only when the circumstances that trigger it, co-join to announce its presence.

Whether its resonance, cavitation, 'ice-making' through unforeseen expansion, or fire due to faulty seals / fractured lube oil lines, its the critical "nth degree" that conspires to trap even the most savvy. Simply design to prevent it. Yep, but you have to appreciate what those conditions might be, before you can even start thinking of a programmable routine that will identify a problem.

So, ultimately there will always be a "nth degree" lurking to bite you in the b:mad:m when least suspected.

In the case of QF32, from the moment that climb thrust was set, an abnormal "trend" was apparent in the monitored conditions of No.2 when compared with the averaged data monitored from the remaining three engines. A simple comparison routine would have revealed a potential "nth degree" was developing at least a minute before the proverbial hit the fan.

[Turbine D]

Or would the cost to the airline be about the same as fitting GE engines?
There isn't another RR engine that would perform the A-380 task, but there is an engine (partly made by GE & partly made by P&WA) on some A-380's, the GP7200. Emirates and Air France's A380's have been in service for sometime using GP7200's.

From an Airbus ceremony in Toulouse, France, December 2010:

“The GP7200 engine has been performing very well on the A380,” said Alain Flourens, Airbus Executive Vice President, A380 Program. “We congratulate the Engine Alliance on its 100th Engine milestone and look forward to many more engine deliveries to come.” The GP7200 powers the Airbus A380 aircraft, and the 100th engine is destined for Korean Air's first A380. The airline is expected to take delivery in May 2011. There are 19 GP7200-powered A380s in service. EA launch customer Emirates began operating the aircraft in August 2008 and received its fifteenth A380 on November 30. Emirates is Airbus' largest A380 customer with orders for 90 of the super-jumbo aircraft. Air France entered service with the GP7200-powered A380 in late 2009 and has four A380s in its fleet and eight more on order. Other GP7200 customers, in addition to Korean Air, include Etihad Airways, Air Austral and International Lease Finance Corporation (ILFC).

[Smilin_Ed]

Could GE/P&W provide enough engines to replace the RRs in a reasonable time?

[Flapping_Madly]

The GP7200.This is not good reading for RR then:-

Trent 900 vs. GP7200: Competitive pressures getting too hot? The k2p blog (http://ktwop.wordpress.com/2010/11/05/trent-900-vs-gp7200-competitive-pressures-getting-too-hot/) Bit of a morbid article .

Or. Was the Trent 900 that disintegrated just a rogue engine and while other copies may have problems and need close attention they are generally behaving themselves. And as time goes by and operating experience increases this incidence will assume its correct importance in the scheme of things.

This and the other thread have been immensely interesting and instructional. Do the guys at RR and Airbus read it do you think?

[Flapping_Madly]

Turbine D
Please explain to me why the 800 or 1000 would not be suitable. They have as much thrust if not more. What makes the 900 the only RR engine for the A380 ?
Thank you. (Remember I'm only SLF):)

[bearfoil]

mm43

Hi. the Trend (T?) was monitored, but keep in mind the EEC must command different settings for each engine to get normed Thrust across the wing. Also, to make a statement such as that means we need to fault the Aircrew for acting late. They did NOT. The EEC commands the engines, to include Monitoring. Each DEP is different, but only in Memory, it is tailored to each powerplant individually, due each engine's "personality" after Test.

Your statement is open ended, did you mean the "Monitoring" was not done (By Crew)? Or did you mean the Monitoring was done, but too late for the crew or the EEC to act (The Machine).

This engine may have Three completely failed Shafts, but the EEC will "Make Up" an RPM to send to the cockpit for the LP and IP, and pour fuel by the actual RPM of the HP Rotor. I am not kidding, and I apologize for bringing up the "Dilemma".

Smilin' Ed

You are jesting, No?

Turbine D

Emirates speced the GP briskly, without so much as a nod to Derby. Some have said they knew something......

Flapping Madly

k2p blog have a bit of an attitude re: RR. (Who, Me?)

[Smilin_Ed]

You are jesting, No?

No, I'm not jesting. Re-engining with GE/P&W could not be done overnight or even within several years. It's not like asking McDonald's to take up the slack when a nearby competitor goes out of business.

[bearfoil]

Hmm... It is exactly like asking MacDonalds to take up the slack for a foundering competitor.

Eliminating the T9 on the Whale would be the Death Knell for RR.

Not that they don't face it already.

It is a long discussion, and I've had it before, Rolls couldn't sell Cracker Jacks Charms if they lost the TRENT. The only reason the 9 would be terminated is if it kills someone. There is no "Out of the Blue" any longer. The AD's spoilt that bromide. The latest cage of #4 972 (Qantas) may be non survivable. There are no lemons in Aviation, only metallic Cyanide Pills.

Hiding in innocence of new limits (Comet), or even loss of wings (C5-MIL) the game is up. Rolls knows why, and in desperation to maintain a facade, is pretending like it is a "Mystery". "New and Unknown Fuel Characteristics"?? "Misbored Pipes" ?? Faulty Bearings, etc. etc. The Public seems docile because they are ignorant. When they find out they've been had, the "World is not Enough".. just sayin'

[Turbine D]

Flapping Madly

Please explain to me why the 800 or 1000 would not be suitable. They have as much thrust if not more. What makes the 900 the only RR engine for the A380 ?

I think the bottom-line to this question is SFC (specific fuel consumption). When Airbus decided to examine the possibility of building a new long range transport, larger than the B-747-400, Airbus went to work internally on the design. They came up with everything new, especially the wing. As part of this wing development they tested various designs and eventually tested the best candidate with various nacelle designs, before settling on the final nacelle shape and size. Then they went to the engine suppliers with a recipe of ingredients they needed, particularly to achieve the maximum range goal of the aircraft. The engines had to:
- Produce 70K lbs. of thrust with some growth potential
- The engines had to fit inside the designed nacelle
- The engines had to have a SFC capable of delivering the maximum range plus minimum reserves.
- The engines should not weigh more than "X" and it must attach to the pylon at these points.
- And there were many more technical requirements such as noise.

Pratt and GE were unsure of the market size and neither thought they wanted to spend $2B US to develop an engine in a marketplace that could be divided up three ways. No one had an engine that met Airbus' requirements. So Pratt and GE decided to form a new company (Engine Alliance) and take the best of the PW4000 and the GE90 and come up with a design to meet requirements.

Rolls Royce decided to develop the Trent 900 with some technology coming from the previous family of Trents, some new features.

And IMHO, this is how it got started. The biggest challenge was SFC, especially for Rolls Royce. Traditionally, 3 spool engines (Trents) are shorter than two spool engines (GE or PW) and when contained in shorter nacelles, overcome a deficiency in SFC compared to a longer engine that has good SFC. But the Airbus A-380 has longer nacelles aerodynamically matched to the new wing.

So if you look at SFC:
GE90 SFC (SLS) 8.30 mg/N-s (cruise)
Trent 882 SFC (SLS) 15.66 mg/N-s (cruise)

Cruise at altitude is where most of the fuel is burned in long range flights.

The Trent 800 probably wouldn't meet the SFC target.

So the GP7200 uses a GE90 core with a PW fan and LP turbine.

Rolls Royce had a big challenge and needed all the best of the new technology to narrow the gap, and for the most part new technology worked with the Trent 900 to meet the SFC target.

The Trent 1000 came along later specifically designed to meet the Boeing 787
Requirements and as such, may not meet the A-380 requirements.

This represents my best estimations of this and it could be wrong
(disclaimer).

[mm43]

Bearfoil;

It wasn't apparent to me that I was implying the crew should have monitored for the trend. No, the trend monitoring would have revealed the abnormality IF the EEC had a routine for doing so.

At this stage, it is after the fact. Done before, may have provided a different set of facts.

[Smilin_Ed]

Bear:
Hmm... It is exactly like asking MacDonalds to take up the slack for a foundering competitor.
Eliminating the T9 on the Whale would be the Death Knell for RR.

It could also impact Qantas and anyone else who is dependent on the long-range fuel specifics promised by RR for the A380. If the T9s and other large RR engines keep having catastrophic failures (or having to be shut down due to impending failure), and fuel prices continue to escalate, everyone, airlines, EADS, and RR will suffer. We may be on the threshold of the scenario put forth in the k2p blog where one engine supplier inherits a monopoly.

[Turbine D]

Flapping Madly

Do the guys at RR and Airbus read it do you think?

I think they probably do. Anybody in public business today is interested in what is being said, right or wrong about what they do or make. Years ago my wife had a TV VCR home taping business where she would get requests to tape news shows on 7 different TV stations we received. In times of crisis (like the 900) a business would send a courier to the house at midnight to pick up the tapes from the 11 PM newscasts so the tapes could be taken to the local biz-jet airport to be flown to the business involved for review. Today, if you "Google" almost anything pertaining to the 900, you will run across a PPRuNE post or two. It's the age of instant "IT".

[Turbine D]

Or. Was the Trent 900 that disintegrated just a rogue engine and while other copies may have problems and need close attention they are generally behaving themselves. And as time goes by and operating experience increases this incidence will assume its correct importance in the scheme of things.

I would certainly believe British Airways is counting on this being the case with their recent order!

By the way, except for the current flying pilots, first officers and flight attendants, we are all SLF!

[bearfoil]

The Net allows for instant everything, and choice is the name of the game. It is most important for eliminating the "Puffery" of salesmanship, but also allows nitwits and proctozens to have a say. On the whole, the fact that there is no place to hide any longer for those who would endanger the Public, the venue is a plus. Google has several thousand of arguably the smartest humans on the Planet keeping their engines in Tune. "Imagine That, Fuel that doesn't follow the Rules", etc. "Golly, Friedrich effed up, he needs a stern talking to." The games are over. No longer a quick official guess (Lie), followed by sufficient time to allow the masses to move on. The chip has an eternal memory, and its contents are available in nano seconds. No more Corporate deference to the bottom line, the Bottom is now on the line.

One thing still rings true, and most likely always will. Bury the Dead, Tell the Truth, and Fix the Problem. Those who at one time made a living fooling the Public are now in the soup line. There is a God.

[bearfoil]

Sorry, I misunderstood your meaning. This latest incident of the T9 reports the Captain and F/O noticing a trend of Oil loss, and spooling down to (Flight) Idle. A Captain's commanded loss of an engine's power due loss of Oil sounds like a Boeing StratoCruiser, or Connie. An Airbus??

What will they think of next.

Without putting too fine a point on QF32, the outcome was to pull the EEC on engine Drop, and immediately change software. Are you understanding me when I say that the Software was not and is not the Problem?? The Engine has a current service life of six months. The software doesn't extend that, it (hopefully) allows for an auto shutdown in time to save an a/c. It is a Patch on a Hemorrhage. (imo).

[mm43]

The most recent incident, now in "Spotters Corner" wasn't my concern.

All I was trying to say was, that on a 3 or 4, with all engines set up to do the same thing, it is most likely that the EEC data from each will respond with similar trends. So as well as the EEC monitoring each engine, a comparison of trends will provide the first indication that any one data point is moving at a faster rate than the average of the same data points from the remaining engines.

Its not the absolute values we should be interested in, but the rate of change and direction of deviation from the mean - that's the first indication of "trouble up at mill".

[DERG]

BEAR....

"I brought this up on the BA038 thread, relative to fluids Stall at TOGA chat. I also injected it early on in this thread, (Actually the original). The FOHE is a candidate for failure both in cooling/heating capabilities due its position on the Fan Case. Here, the unidentified (though known) Harmonic wreaks its damage in a trail of Wear to all parts in the Core."

Thanks for bringing this back into the thread. This aspect is important, explains the high oil temps. Introduces another set of variables we really could do without. :oh:

Time for some R and R. Think you might will like this called the "Nth Degree" and sort of mimics the nature of global aerospace business.
YouTube - Morningwood - Nth Degree (http://www.youtube.com/watch?v=t-ORHKxaXmA)

[infrequentflyer789]

The Trent 1000 came along later specifically designed to meet the Boeing 787
Requirements and as such, may not meet the A-380 requirements.


T1000 is bleedless for a start, which is no problem on the 787 it was designed for, but will clearly be an issue plumbing it into a 380 that is expecting bleed air.

[WEATHERKEW]

Having followed this thread religiously ever since the incident, I sometimes wonder whether the RR engineers involved in the investigation/redesign(?) feel the urge to respond to some of the assumptions and assertions posted on Pprune. Are they bound by a vow of silence, or are some of them PM-ing the more qualified members on the forum, and feeding them titbits of information? The absence of public statements from RR regarding the full extent of the problem, and the progress of its resolution, only results in more speculation regarding the future of the Trent and the Company. They, engineers and management, must know this.

Whatever the outcome of the matter, I have learned and understood a great deal about the finer points of gas turbine engine design from some of the more qualified contributors, but I have also detected an increasing tendency by some, to take delight in flagging up the dire potential consequences to RR of a failure to resolve the issues. There are some posts which add nothing to the debate, but serve only to bolster the self-regarding egos of the conspiracy theorists.

My hope is that our fears are unfounded, for the sake of passengers, operators, employees, and the reputation of one of the last remaining UK world-class engineering companies.

[forget]

There are some posts which ...... serve only to bolster the self-regarding egos of the conspiracy theorists.

Standby. He'll be along in a minute. :hmm:

[DERG]

Hiya FORGET on the nose..hahaha:\

"My hope is that our fears are unfounded, for the sake of passengers, operators, employees, and the reputation of one of the last remaining UK world-class engineering companies."

Your fears are unfounded. The aircraft and the public is safe. From a commercial view point RR has a bursting order book. This is just a minor technical hitch that was unforseen.

My rant is why it happened. As it turns out the technology we thought we had we actually did not. You can forget the conspiracy stuff. If you want cedibility the only technically qualified contributor here is Turbine D. The rest of us are mainly retired onlookers. So if you read all the posts made by Turbine D and disregard the rest you can be assured of a good understanding.

We were lucky that this event happened as it did with no loss of life. God was with us.

NOTE WELL
I have to add that the logic recorded in the Bayesian paper was more akin to central Europe 1935. This is exactly what happened then. No way will I let that pass.

[lomapaseo]

WETHERKEW

Having followed this thread religiously ever since the incident, I sometimes wonder whether the RR engineers involved in the investigation/redesign(?) feel the urge to respond to some of the assumptions and assertions posted on PPRuNe. Are they bound by a vow of silence, or are some of them PM-ing the more qualified members on the forum, and feeding them titbits of information? The absence of public statements from RR regarding the full extent of the problem, and the progress of its resolution, only results in more speculation regarding the future of the Trent and the Company. They, engineers and management, must know this.

Whatever the outcome of the matter, I have learned and understood a great deal about the finer points of gas turbine engine design from some of the more qualified contributors, but I have also detected an increasing tendency by some, to take delight in flagging up the dire potential consequences to RR of a failure to resolve the issues. There are some posts which add nothing to the debate, but serve only to bolster the self-regarding egos of the conspiracy theorists.

My hope is that our fears are unfounded, for the sake of passengers, operators, employees, and the reputation of one of the last remaining UK world-class engineering companies.


No worries

Nothing is gained by RR responding in any way including feeding info to good or bad shills.

The public generally trusts their regulators and depends on the better press to keep track of major events or rumours in this regard.

Interest pretty much goes with what plays in the press rather than unknown posters on a discussion board. Could be because most of us for good or bad hide our identity :}

For real concerns there is always a phone call or E-mail to be heard or attended to. The industry does have a way of listening to the right people.

[DERG]

Thats the problem lomapaseo, just who are the "right" people?

[One Outsider]

Inventing problems and premises just to have something to pontificate about is not particularly helpful.

I suggest cutting down on the sugar.

[DERG]

"I suggest cutting down on the sugar."

No longer can we just sit down and have a cup of tea secure in the knowledge that we will get the business anyway. If anything will loose the UKs best engineers it will be the "old boy" network. That much is clear.

[One Outsider]

Whatever.

The sugar comment was a reference to you being all over the place like a 6 year old who have eaten too much sugar, posting nonsensical comments on just about any subject.

A friendly advice if credibility and reputation are of any importance to you, if you will.

[DERG]

Thanks for the advice. Got an appointment with the doc in early March:ok:

[bearfoil]

I think the editorial comments are best left to the moderators. What a bunch of scolds!!

Factless Scolds, at that. Sounding like an amateurish send up of Parliament.

"Hear hear!!" "Harrumph", "Bad Form!!" etc. Those who can, do. those who cannot, criticize.

[lomapaseo]

I think the editorial comments are best left to the moderators

I do not agree

Moderators, moderate the politeness of interactions and suitability of topics, but not necessarily the content until/unless it violates forum rules or seriously takes the subject off track.

The opinions, accuracy and relativeness of what one posts are free for dispute and/or discussion, just as you may disagree with what I post now.

[bearfoil]

So we are now completely off thread, and for the pursuance of empty rhetoric accusing one another of Various forms of chemical imbalances, and ignorance of the topic. For one, I see from you 10% of what you can contribute to help further the discussion. You are obviously expert, yet you prefer to withold your knowledge and instead complain about the lack of knowledge evident here. When you yourself are on topic, people read, and learn. When you scold, you waste your talents in pursuit of.....???

None of this should be personal, yet look now at me!! If one's prose offends or annoys, move on!! Why waste the time trying to enforce a personal point of view relative to what presents here, warts and all??

[DERG]

Isaac Newton will wave his invisible hand in the not too distant future, this thread is not done yet. His hand is every bit as good a Adam Smith's. At the moment I am reading all about the business school at INSEAD. This is where a lot of these RR managers get trained. Certain people in a certain condition as Adam said..Smith.

However, the issues raised in the last few posts about the safety of the public need clarifying. Should the A388 encounter an engine problem... here is the performance capability of the machine at the various weights. It is clear from this information that it is a VERY capable machine running on three engines only. My thanks to Trent 972 over on the Oz site.

Derg,
Basic figures @ ISA conditions
@500 Tonnes - 3 Eng max FL300+
@430 Tonnes - 3 Eng max FL350+
@400 Tonnes - 3 Eng max FL360+
@370 Tonnes - 3 Eng max FL380+

The 380 is always comfortable with terrain clearance on 3 engines, even over the Himalayas, no risk bro. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

this was posted on Feb 20 2011.

[dfstrottersfan]

I read recently that Qantas are hoping to return the plane to service. I seem to remember some discussion in the first part of this thread before it was restarted in the Tech log that this would be impossible.

Can anyone point me to a discussion of how this is going to be accomplished?

Maybe it is in this 2nd part - I haven't had the chance to read the thread yet - I didn't realise that the thread had "moved".

[DERG]

Can rebuild anything as long as someone pays the bills. What you read was B:mad:T

[barit1]

I posted (in the original thread) that based on available photos, the hole in the front spar web left the spar caps intact, and thus a temporary repair appeared feasible. This would permit ferrying the bird back to Toulouse where permanent restoration could be done.

The elephant in the room (;)) is the restoration cost versus the market value of the repaired ship (as well as the QF reputation for never writing off an active ship).

[DERG]

Barit1 I see now YES! hahahah :cool: :ok:

[bearfoil]

barit1, DERG, and all,

It won't cost Qantas a penny, unless they want to outbid the JunkMan, to 'salvage' their dubious Hull record.

Four New/As New "C" mod T972 on Rolls, a spar, skin, and systems freshen-up, and off we go. Erm.......Off you go.

I do believe Rolls should pay in Cash for the removal of the 468 brown stains on the upholstery. And new knickers for the CC.

Wait, there may be more than one per each. There were after all, TWO BANGS.

[DERG]

Bearfoil

The current CEO, a psychologist graduate, of RR leaves the company at the end of March. He did a hell of a good job. The new guy is an accountant fresh from a job overseeing a retail operation in Belgium. He should be able to add up, but there is no guarantee that the Bayesians will be booted back to the race track where they belong.

He certainly will be busy, creatively hiding the costs within the bounds of company law. It will be his responsibility to regain the once proud name of Rolls Royce.

[Turbine D]

Some questions, maybe slightly off topic, maybe not:

Why is it that the most prominent UK engineering company goes outside the firm to bring in top leadership and who's education and background has nothing to do with the complex engineering product being designed, produced and sold? Is there not a path to the top for a bright, well rounded engineer to be groomed for the top position within the firm?

Just curious...

[llagonne66]

Just reminds me of an A/C manufacturer that is consistently poaching the automotive business for its top management positions ....:ugh:

[bearfoil]

The Board

This is a true story.

Looking for a replacement CEO, the Board recruited via sub contract with a "Head Firm". Interviews went well, and an excellent choice was made, by unanimous and robust approval. Contract was discussed, entered, and the New Man was invited back to the Boardroom for a welcome and Scotch.

When the new CEO was invited to stand up and address the Board, he led with a question:

"What, Exactly, do you folks build, here?"

[DERG]

TURBINE D

Objectively: There are 14 directors on the board of Rolls Royce. Nine of them have a social science background, one is a chemist, one an an academic engineer, two are vocational RR lifelong engineers. One is from management of United Airlines in the U.S. who gained a business degree.

So we have two guys here who could do any job on the shop floor and do it well. The most academically qualified is Colin P Smith.

Board of Directors - Rolls-Royce (http://www.rolls-royce.com/about/who_are/management/board/index.jsp)

So how come Colin P Smith does not have his hands on the reigns?

Now we go into my subjective reasons why after WW2 the engineers were not well regarded by the guys who had the money: the City of London and the Bankers.

1. The allies won WW2. The UK relaxed.

2. The UK education system after the WW2 was tripartheid. There was the private sector, the academic schools for about 10% of public school kids and another school for the other 90% of kids who did not get the scholarship. 5% of the population went on to university. The privately educated kids were the same mix...but they had a lot of input..this is the "oxford accented" and "old boy" network that led the UK after WW2. Of course a lot of them were not particularly gifted individuals but they had the right accents and talked well.

3. The education system has been a "political football" since 1965. The net effect is that we do not have the support structure in engineering.

4. Culture: beliefs and values. Engineering was not valued in many of the public academic schools and the facilities in these schools was poor to promote craft skills. So engineering became unfashionable.

5. The routes upward for talented shop floor workers were through the "technical colleges" and back in the 1960s and 1970s this was a route many sought and won. Colin P Smith is one such example. Entered at age 18 and went through this system. Looks like he hit the very heights of what was possible too..lots of solid balck type after his name.

6. Rewards. The pay for someone like Colin P Smith at age 18 would have been something like £38 per week. The team of 20 or so practical shop floor engineers he led would have been around £300 per week. This would have been for about a 45 hour week.

7. This was in the UK only. If you look at the UK it is on the edge of Europe and an island of some 55 million people. After WW2 the only competitor the UK had to manufactured goods was the USA..and we still have an export/import charge that hangs on today as a remnant.

8. Business culture. As one young commercial manager said to me when I was around 30 years old: "The trick DERG is to sell people fresh air..thats the secret". That memory remains with me.

9. As the post war years rolled on the City of London became a haven for companies from the USA who wanted a foot in the European market and were keen to adopt the methods of the USA in "wealth creation" The UK was an ideal place to make things because the labour was relatively cheap and the new methods were automated. Beacause the UK is an island the economy and labour markets were effectively trapped and the business managers took advantage. The "suit" became the icon. The coverall was altogether frowned upon.

10. Economics Because of the reasons above and the oil price increase the UK was bust by 1972. In Feb 1971 RR went bust but was restarted with tax payers money just as Airbus was founded. The City of London recovered and continued investing in service industries. Engineering was seen as "high risk" as the Japanese and German products became popular.

11. The net effect: the UK became a finance clearing house. If you wanted to be successful in life then engineering was not high on the list. That is why today we have only two or three people on the board of Rolls Royce Aerospace who are true engineers.

This subjective analysis SHOULD cause plenty of you to comment, all replies welcome

[Flapping_Madly]

Hope this is on topic enough.

Geely Automobile Holdings Limited (http://www.geelyauto.com.hk/en/mg.html)

It is the board of directors of Geely the Chinese firm that now builds the iconic London Black Cab--and lots of other things.

I've never seen so many Doctors and professors of engineering in one place. Make of it what you will.:O

Just my two cents worth.

[DERG]

Yes indeed Flapping Madly. So if so much manufacturing is going away from us in the "west" why should we be so worried about engineers anyway? Do we need them at all? The blue collar skilled worker is under threat unless he is prepared to be itinerant. Perhaps Rolls Royce has got the right mix on the management board after all...perhaps they think that Rolls Royce is like any other manufacturing company..they could just upsticks and relocate anywhere...who knows?

[dfstrottersfan]

I remember our previous PM giving a speech from Clydeside saying how proud he was to be giving the speech from a place with such a great engineering past.

This is honestly not a political point - the thought that ran through my head was why are we not as a nation ashamed that ship building / civil aircraft manufacture etc are things of the past in this country? and why is it that only foreign companies can make money manufacturing cars in this country?

I know of graduate engineers who cannot find a job - we should be ashamed that industry and manufacturing have such low esteem.

rant over

[DERG]

My thanks to KEESJE for this post:

RR is working on new Open Rotor Technology for 3 years, with full scale demonstrators in the not to distant future. A third round of windtunnel test will start soon. They say they solved noise issues.

FARNBOROUGH: R-R urges Airbus. Boeing to reconsider narrowbody re-engining plans (http://www.flightglobal.com/articles/2010/07/14/344404/farnborough-r-r-urges-airbus.-boeing-to-reconsider-narrowbody-re-engining.html)

Anyway it seems more A320NEO orders in the not to distant future, AirAsia, Jetstar and Lufthansa.
Lufthansa, Airbus Said to Negotiate $2.5 Billion Plane Order - Bloomberg (http://www.bloomberg.com/news/2011-02-23/lufthansa-airbus-said-to-negotiate-2-5-billion-plane-order.html)

Jetstar Evaluating Airbus NEO | AVIATION WEEK (http://www.aviationweek.com/aw/generic/story_channel.jsp?channel=mro&id=news/awx/2011/02/21/awx_02_21_2011_p0-291412.xml&headline=Jetstar%20Evaluating%20Airbus%20NEO)

Keesje is your man for thus stuff..Thank You!

[ukc_mike]

Why is it that the most prominent UK engineering company goes outside the firm to bring in top leadership and who's education and background has nothing to do with the complex engineering product being designed, produced and sold? Is there not a path to the top for a bright, well rounded engineer to be groomed for the top position within the firm?

In 1971 Rolls Royce went into administrative receivership and then was nationalized. At the time the company was being run by engineers but their published accounts were being used as a classic example of a company heading for financial collapse.

[Turbine D]

Some very interesting comments and observations to my original question, thanks!
Here is an interesting read. The pendulum swings from one side to the other over the past 40 year, maybe?

http://www.econ.uniurb.it/siepi/dec03/papers/lazonick.pdf

[bearfoil]

I have made a study of Leadership at the Commercial level for the last two years, among friends and colleagues.

I prefer to start with the straightforward and simple view. If it is correct, no time is lost making things complex or difficult to explain.

The Leader: Tell your People what you want, and how long they have to produce.

The Manager: Tell your people what the Leader said, and explain to your people how to do it.

It is not more complicated than that.

The Man responsible for such a "Naive" view?? Patton.

The civilized world has begun (?) to believe its own nonsense, that work can be done simply by "Asking" and believing the result will be stellar.

The Drift away from Individual excellence into murky collective "Consensus" started with Marx. It has travelled unabated since the mid 1850's, with few sparks of brilliance to thwart its lurch back into the Stone Age.

"One CANNOT strengthen the Weak by Weakening the Strong..." (Lincoln).

The Barometer of Failure is an excess of money.

[DERG]

Bearfoil

If you read DAS KAPITAL by Karl Marx you will see how the CEOs et al operate. All they do is use this theory for their own agenda. They were all trained in this theory if they went to university here in Europe in the 1970s because it was fashionable. This is a "trade secret" I guess.

The result is always the same: a very small bunch of people live very well off a very insecure big bunch of people. Adam Smith in his THE WEALTH OF NATIONS describes this small greedy bunch as "certain men in a certain condition". A contemporary example is Michael O'Leary of EasyJet.

Adam Smith is the "good guy" and won out in 1989 when communism collapsed.

Make no mistake though, the other stuff is still used. Very successfully too until someone like Isaac Newton comes along and scares 'em. Ahem!

TURBINE D

"The pendulum swings from one side to the other over the past 40 year, maybe?"

http://www.econ.uniurb.it/siepi/dec03/papers/lazonick.pdf

That paper was fascinating. I see INSEAD was involved, the MBA finishing school for the muppets who are sitting on the RR board of directors.

There is no question...they have lost control of the company. Isaac Newton is messing with their pendulum. It will cost them many times the £56m they have set aside as a fund to repay Qantas.

Just how much this will cost?

[ZimmerFly]

Engines run smoothly again as Rolls-Royce is named top brand
It experienced a wretched year that saw its chief executive step down and the failure of one of its engines that could have resulted in the crash of an Airbus plane carrying 469 passengers. Then last week one of its bosses accompanied David Cameron on his ill-fated tour to bang the drum for Britain's defence industry.

Yet a remarkably fortuitous sense of timing, coupled with its renowned sense of British stoicism, has led to the Rolls-Royce Group toppling Microsoft as the most respected brand in the UK.

Compiled by The Centre for Brand Analysis, which reflects the views of a panel of 2,000 business professionals, Rolls-Royce Group has taken the top spot in the Business Superbrands index for the first time since 2007. More than 1,100 brands were shortlisted for the survey, judged by professionals from the marketing, financial services and manufacturing sectors. Brands were rated against a number of criteria including quality, distinction – and reliability.

But the champagne at Rolls-Royce's Derby headquarters may have to be kept on ice for a while longer. The survey was compiled just before the dramatic failure of one of its Trent 900 engines, which exploded while powering an Airbus A380 on a Qantas plane last November, forcing the jet into an emergency landing in Singapore.

Engines run smoothly again as Rolls-Royce is named top brand - Home News, UK - The Independent (http://www.independent.co.uk/news/uk/home-news/engines-run-smoothly-again-as-rollsroyce-is-named-top-brand-2227589.html)

[lynn789]

I wonder if RR still has any corporate memory of their hyfill disaster

[Turbine D]

ZimmerFly

But the champagne at Rolls-Royce's Derby headquarters may have to be kept on ice for a while longer. The survey was compiled just before the dramatic failure of one of its Trent 900 engines, which exploded while powering an Airbus A380 on a Qantas plane last November, forcing the jet into an emergency landing in Singapore.

Timing is everything when it comes to effective P/R, eh? Not to minimize the gravity of the Qantas T900 situation, but more often than not, the release of good news, a self-fulfillment story is overcome by a negative event before the good news reaches the printing press. Could be the creation of sayings such as "knock on wood", etc. Now, a re-do of the survey may show a much different picture.

[DERG]

Another London bound Qantas A380 engine problem – Plane Talking (http://blogs.crikey.com.au/planetalking/2011/03/01/another-london-bound-qantas-a380-engine-problem/)

"A Qantas Airbus A380-800, registration VH-OQG performing flight QF-31 (scheduled dep Feb 23rd) from Singapore (Singapore) to London Heathrow,EN (UK), was enroute near Ashgabat (Turkmenistan) when the crew observed the engine oil quantity for engine #3 (Trent 972) reduce. The crew reduced the #3 thrust to idle, continued the flight to London crossing Europe at FL360 and landed safely in London about 5 hours later."

Source: Aviation Herald.

[bearfoil]

Qantas flies eight whales, none at this point with less than "C" Mod engines (972)

Of Thirty two total engines on wing, two have experienced this oil feed issue in the last two weeks. Assuming the "Working Loose" problem, what Ben doesn't say is that this most recent incident was also likely losing Oil necessitating the roll back.

Mathematically, there is a .33 chance in one hundred that two engines will behave this way on the same flight. It is actually worse than that, since the problem is identical, and rollback for any reason is less likely than losing two when a demonstrated fault has repeated.

Call it one in one hundred.

Thankfully no less an authority than Rolls Royce itself has stated its engines are perfectly safe.

Whew!! No worries, then!! :D

[DERG]

Yes Bear that is what the Bayesian Staticians and the board of Rolls Royce determined. The machine has four engines and even if one failed the probability of a second failure on the same 'plane would be improbable.

Statistics are a useful tool for so many purposes and are much beloved of the social scientists in academic circles.

I am sure Rolls Royce are waiting until the T972s are out of the news but with 32 units in service it is unlikely that this will happen. The only way they can currently prevent the engines from failing is to replace them before another event happens.

Thay can't because:

1. They just don't have enough spare engines

2. They cannot afford to borescope them after every cycle.

3. They are already committed to contracted work elsewhere.
viz. the A380 production line in Toulouse.

4. They cannot allocate resources to redesign the engine because of
new technology impending viz. the open fan designs

5. To employ radical methods to address #2 above would cause a minor
cash flow crisis. Independent aero engineers are not cheap to hire nor will they sign off anything that is unsound.

So all in all the situation will remain as it is for the forseeable future. If RR decided to follow #5 above they could or will be presented with rejection notices which would ground the aircraft. Moreover the ATSB could ground the Qantas fleet of A388s. An impass situation.

The logical solution is for RR Derby UK to suspend deliveries to the Toulose production line in France, and ask the customer to accept the EA engine instead. I am sure if the 14 members on the board of RR had the pragmatic outlook common within the global engineering industry they would enact this policy.

[bearfoil]

TRENT

Which is more likely? A TRENT shakes loose an oil couple, (be certain the P/R release includes "External" oil line), or Fuel Stalls in the FOHE due itinerant resonant frequency??

Or are we again up against the dolt who cannot line up a bias on a drill bore?? Times "X"?

How many duff pipes are aboard, Clive?

Look, a safety rollback of an operating powerplant is not cute. It is especially worrisome when it results from "unknown" (unspoken?) problems in a powerplant that has a long history of problems staying in one piece. The trail of failure leading to the uncontained burst includes the current issue, without exception. An institutional mandate exists to ignore the AD, shuffle "blame" around without cease, and act as if nothing is ongoing.

In an engine without a history of breaking, the oil loss and subsequent shutdown would be remarkable, but in this case, the lack of apparent concern is breathtaking.

Is quiet supposed to be a substitute for competence?? As I recall, "Low Oil" on the ECAM, displays with a sensing by the EEC of four quarts left.

[DERG]

"the lack of apparent concern is breathtaking."

Not when you get inside the mind of the Bayesians and the board members of RR.

Like learning a language once your ear is tuned you can understand. This is a calculated risk, simple as that.

There will be projections of total loss costs already planned.

This is difficult to believe but we, the public, are just players. There are no morals involved here. This situation will not change soon.

[Machaca]

bearfoil:
An institutional mandate exists to ignore the AD, shuffle "blame" around without cease, and act as if nothing is ongoing.

...the lack of apparent concern is breathtaking.


I respect your desire to obtain the full truth to this incident.

However, unless one personally has access to all the key inside personnel and communications at all the firms and agencies involved, making such strong and sweeping determinations from the outside proves nothing.

One could derive the same conclusions from observing the daily arrangement of vehicles at the Derby car park.

[bearfoil]

Not wrong.

[DERG]

"One could derive the same conclusions from observing the daily arrangement of vehicles at the Derby car park."

You mean the race horse meeting called the DERBY? I do not wish to be rude but if you believe that the world will be silent you are seriously mistaken.

Many of us have been seriously disturbed at the incompetence and callous disregard to the safety of the public before and during this saga.

The T972 has a serious problem and is currently in service with the continuing problem. This is not going to be swept under the carpet until the problem has been solved.

The ATSB and Qantas have shown an enormous good faith toward Rolls Royce as has the public.

"However, unless one personally has access to all the key inside personnel and communications at all the firms and agencies involved, making such strong and sweeping determinations from the outside proves nothing."

What you mean to say is that the discussion and conclusions we made here are conjecture. The strong and sweeping statement was made by the T972 engine itself when it exploded.

Maybe if one of your loved ones was sitting next to the wing in that A388 that day you would not be so cavalier. The fact is Mr Machaca that many of us will persist with this discussion until the situation is resolved.

[sooty655]

Many of us have been seriously disturbed at the incompetence and callous disregard to the safety of the public before and during this saga.

DERG, I'll try once more. Will you please stop this nonsense. You are a retired civil engineer with not the vaguest connection to aviation. You have admitted to having personal 'problems'. You know SFA about aircraft. You know even less about turbine engines. You are not remotely qualified to comment on the abilities of Rolls Royce. So stop.

Your other posts today, 38 of them so far if the post counter is correct, tell their own story.

[lomapaseo]

I'm prepared to join the campaign. Anyone else out there want to get this incessant drivel stopped?

No way except voluntarily. Thats the nature of a well behaved internet. Just remember it could be far worse if it were on other sites with folks choosing up sides etc.

One can always use the "ignore" button feature (I haven't yet on this site) and/or respond only to posts which move the subject along in a productive manner.

[bearfoil]

Machaca

Most unlike your ordinarily well thought out and data laden postings.

In flight uncontained engine failures this year: 2

Commanded rollbacks due Oil and other issues: four.

Engines off wing to be rebuilt with new shafts, bearings, and collateral structures including EEC re program and DEP refit?? ALL OF THEM. EVERY SINGLE ONE.

Purely precautionary, RIGHT?? NOT.

I base my comments on the evidence in the Public Domain. There is more, but unavailable to the Public.

Have you been reading this thread??

lomapaseo Your level headed and reasonable comments are appreciated, as always.

[LandIT]

...the HP/IP structure inspections are not
considered necessary anymore and AD 2010-0242R1 is cancelled.

EASA Airworthiness Directives Publishing Tool (http://ad.easa.europa.eu/ad/2010-0242-CN)

[bearfoil]

Everything about the TRENT's shortcomings suggest a vibration environment that was not designed for. Not particularly alarming. However, there are identifiable structures within the Modules that give evidence of an inability to withstand something that should by all reason be a slam dunk. Early Bearing failure, followed by unusual and surprising wear signatures at the single most important structure in the Powerplant, the Joints of the two articulating Shafts. These Splines are not life limiting, ordinarily, as other patent foibles will cause an offwing strip well ahead of any weakness in the Coupling. Just after the Burst, RR stated the failure was in the Rigid Coupling, and even though additional findings have been introduced since, they have not backtracked. Likewise, cancellation of post burst emergency ADs is to be expected; "better safe than sorry".

What is left is the fourteen month journey of the very problem that by Rolls' statements caused the burst. Oil Fire, Overspeed, Transient Ductility in non ductile material, etc. etc. Hot Oil, Oil Tube fracture, and on, and on.

Rolls have accomplished what needed to be accomplished, and without a Regulatory grounding of the Type. This had the added benefit of keeping the "C" MOD Proprietary, and away from Public scrutiny. The Inspections of the "C" Mod are known, however, and how they relieve the manufacturer of disclosure and a further exercise of responsibility is the key to current philosophy relative to the Fox guarding the Chickens. Thus far, just a few feathers, nary a drop of Chicken Blood.

[Turbine D]

Anonybocks

My guess would be that the external oil leaks being experienced by Singapore are probably due to vibrations where the tube fastening nuts are vibrating loose. Rolls Royce, in proceeding through the various Mod revisions probably made changes to the frame that support the HP/IP rear bearings to both strengthen and stiffen it and to also eliminate the infamous stub pipe that broke on the Qantas A-380. In doing so, these changes were made "on the fly," so to speak. However, all the piping on the outside of the engine can react differently when changes are made to the engine structure. Not only that, this maze of tubing is the most difficult to wring out in terms of vibrations. There are all sorts of "tricks" that can be done to stop tubing from vibrating, but, prediction it is one thing verses in flight experience. It is easily fixed once it is determined which tube (and the location where) is vibrating. I think that is what is happening now. Singapore has more A-380's in the air on any given day, perhaps at times, 2/3 of the entire A-380 fleet. So they are going to be the flight leaders in experiencing this annoying problem.

[bearfoil]

In this case My surmise would be to give RR the benefit of the doubt. Let us assume that this powerplant is under rather intense scrutiny v/v inspections, and compliance. Oil Issues are at the forefront, and it would be counterintuitive to simply lay off loose nuts at their door.

The Oil Pump is located on the external and aft area of the external gearbox, next to the filter, a non-bypass type, ~ 125 microns, cleanable three times. The Pump is a vaned type, equipped with a pressure relief valve set to 600 psi. When this PRV pops, Oil is redirected into the inlet, similar to a spill valve on the Fuel side.

There are nine scavenge pumps arrayed on the gearbox, each with provision for a chip detector of the screw in variety. The Oil goes directly to the FOHE or in the case of cold bypass cooling, to the Air cooler (OIL).

Each of these fittings needs to be cycled at least once whilst in the shop or on the ramp during an inspection, along with the external connections into the core. That is a lot of opportunity for missed checks in the boxes. Only five conditions of loss of Oil since Burst? not so very many.

QF32. Note the Oil Quantity during the EEC log at Burst. It drops a quart or two, then regains its level. I think this is not an oil leak, but could be indicative of a flow problem, not a loss of quantity problem. The oil drains from the bearing boxes via gravity into a scavenge rail, or gallery. Vibration has other outcomes when fluid is flowing, other than nut loosening, imho. Foaming, Sloshing, etc.A temporary drop in "quantity" at the Oil Tank does not necessarily signify missing OIL, only perhaps missing temporarily from the ceramic resistance stacks that feed the EEC with quantity reads.

[barit1]

I would be most curious how the 125 micron non-bypass filtration was chosen. I might have expected a finer mesh.When this PRV pops, Oil is redirected into the inlet... Not so sure of the wisdom of directing the relief oil right back into a tight loop. On a very cold start, the relief valve might be open for some time and there could be quite a thermal buildup in a very small loop. Why not direct the bypass into the scavenge side, then back to the tank? Warm up the whole system!

[bearfoil]

At first blush, I would suggest that smaller than 125 microns would not be metallic particles, reasonably the only material that would be expected in the OIL system other than OIL?

Re: "Tight Loop". Rolls thought it good to go........

[lomapaseo]

Some addititional info on SIA TRENT 972 oil leaks.

Interesting to note the statement:-

"The issue that caused the leaks was identified and corrected"

Which would appear to rule out vibration, although no further information is given.

"Which would appear to rule out vibration"

Not necessarily

First off, I don't see any link with these latest external leaks to the reported factors in the original thread subject. internal oil leak

However vibration is everywheree in the operating environment of a jet engine. Since this is recognized by the designer the response is to stiffen and/or dampen the responding bodies to ensure that no metal to metal rubbing takes place and/or that vibratory nodes do not exceed acceptable stress levels..

For external parts the most susceptible parts are plumbing which necessarily stands off from its mounting points around the engine casing and snakes back and forth under and over other pumbing or wiring harnesses. The initial development testing purposely excites the whole engine carcass and looks for problem areas in this regard and then provides brackets and fixings to address any issues.

What often happens later is that something gets changed like a new pipe design added or even a new accesory is added by the installer thus setting up a new set of end conditions. Of course it has been known that even maintenace actions on an engine have removed and failed to re-install the specified brackets versus the latest Service bulletin change spec.

Lots of engines have gone through this teething problem and the outcome has been mostly minor in nature but a pain to track down and universally fix.

not saying ths was the case here, but let's keep an open mind unless you have the hard facts of cause-effect-corrective action.

[john_tullamarine]

14/274 - note for myself

[bearfoil]

108TD, 381AP

TRENT 700. Discussed at length in the BA038 Thread, the purported "cause" of Fuel "Starvation" in both powerplants, seven seconds apart, was Vibration. Although Boeing, Rolls and others could not demonstrate the actual trail of failure leading to Hull loss, it was reported that vibration played a role in "Dislodging" Line Ice into the FOHE head. At the Tubesheet, this ICE collected and deposited from the tubesheet face backward, until choking the 177 tubes from fuel delivery. The "Solution" (via AD) then, became to 'trim' the tubes back flush to the FOHE diaphragm. Since no ICE was demonstrated in test at Renton, It is completely appropriate to fix blame for this Hull Loss on vibration alone.

The later incident involving the TRENT on NorthwestAL over Montana produced a fix that had little to do with ICE accretion, but mainly directed the Pilot to descend, and Throttle back, at which time the "ICE" will have "melted" (though the ICE had never been replicated in test, right?)

What follows a retardation of cruise Thrust and loss of Altitude is the migration away from Vibration that may have been causing Fuel issues, absent ICE.

To my knowledge, no information exists in the public record that establishes Fuel Line ICE as the cause either of BA038 or Northwest accident/incidents. airfoilmod and one or two others were on about harmonics and resonant issues in that situation as well as here.

An absence of evidence is not always evidence of absence.

The linkage is apparent, in that fluids in the external plumbing were affected at high levels of Thrust, mechanical damage was evident, and "problems" with fluids supply/cycle/consumption continue........

Likewise a drop in RPM "repaired" the 'problem' almost immediately. Faster than ICE can melt? It could be reported that way, to be sure.

Unlike BA038, the testing appears to be conducted in revenue flight.

[35YearPilot]

Bearfoil : "Yes, just those. Keep in mind, the QF32 #2 IPT failed at a Thrust value of 72,000 POT

Wrong: It failed when at a DCL1 power setting of 96.4% of full thrust = 69,400 lb thrust.

The 900 can produce 80,000 POT. Wrong: It is rated at up to 84,000 lb (http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/09b47c27a9cfb982862573080054f9ea/$FILE/E00075EN.pdf) and has attained thrust on a test bed of 93,000 lb

[JuergenP]

360 hits in in two days..not bad...you have a member here called... w w w does some posts over on Mr Hradecky's site.

Got one of mine deleted over there about saftey issues and regulation...makes ya wonder does it not?

[bearfoil]

erm... 72,000 POT, rated.

Noted. Your point is?? GE made 127,000 POT on stand. Max continuous is in discussion, No?

[1a sound asleep]

Lots of rumours flying about re the repair job on the plane. Apparently nothing has happened and the parties are still fighting it out. Allegations Airbus is nervous about twisting of the frame between the wings.

[Old Engineer]

Just as background to the information posted by sound asleep, the torsional stiffness of a hollow prism (such as a wing) would depend on the area enclosed by the structural cross-section of object, in addition to the thicknesses of the enclosing cross-section. Here this would normally be the vertical surfaces of the forward and aft main spars, and the horizontal upper and lower surfaces of the wing between these points.

[Note: To some extent the relatively thick vertical webs of the spars cannot be fully utilized in torsion, as the wing surfaces are not comparably thick; additionally, the square corners on this section add to stresses making these regions less efficient. But these complications are basically the same before and after the incident, and so can be ignored in visualizing the basic problem (if not ignored in analyzing it in detail).]

The problem now is that the forward spar is missing in action to some extent. A tear in a surface loaded in torsion (twisting) is a serious problem, as in general the surface must be continuous to satisfy the mathematical condition of enclosing an area. Discounting the damaged forward spar entirely, the area enclosed would be reduced, perhaps to 3/4 or less compared to the undamaged condition.

This would be so even though the forward spar only carried 5% of the load, as was posted sometime back, IIRC-- presumably the reference was to vertical load. And of course openings in shear surfaces can be reinforced, but this is not easy to calculate. And one can say, well, just plug the geometry, as damaged, into the analysis program. This too can be much more easily said than done, as explained following.

That is, every added node is a problem beyond a certain point. It is always necessary that the load matrix operate on the stiffness matrix in such a way the the output matrix of stresses can, first, actually converge to an answer; and, second, that the output stresses are actually correct values. I omit any references to this as I am speaking from the experience of having had to deal with large-matrix structural grid analyses that did not initially converge, even using very sophisticated programs. One's analysis costs can quickly rise if your repetoire of input tweaks fails. (Well, that's how I did it in my day.) OE

[bearfoil]

Old Engineer

Howdy, you've been missed.

Is it not nearly impossible to test an engineering solution in situ ??

I think the wing is complete toast.The Port wing, that is. It is virtually impossible to warrant a repair as new, since falling short means a failure, and "overbuilding" produces such losses in efficiency and economy due to weight??

This is not a normal challenge, since the Burst damaged an airframe that had every (contractual) expectation of 'limitless' service life. There is no contractual obligation on the part of any of the three players to repair.

Qantas has no interest in flying a "bird in the sling", Airbus would quote astronomical costs for a one-off (and rightly so), and Rolls (although their Pride is not quantifiable), may not want to risk Corporate survival on a crap shoot. The Insuror(s) will always quote the low ball, but they (most likely) wouldn't push too hard for a rebuild, given the others' interests in coming out whole.

Anything further on the 'seventh note' in the seventh chord??

[forget]

I think the wing is complete toast.The Port wing, that is. It is virtually impossible to warrant a repair as new, since falling short means a failure, and "overbuilding" produces such losses in efficiency and economy due to weight??

Fit a new (identical to the original, same weight and warranted) wing?

[bearfoil]

Absolutely. That makes a great solution. Who would quibble? :ok:

[35YearPilot]

At last - the forum is back on topic!

I agree - new wing or a new acft.

[lomapaseo]

I agree - new wing or a new acft.

Try that with your auto insurrance carrier some day

In the long run the decision does involve considerations of meeting regulatons as well. Simply opting for feel-good decisions on the fly to suit what sounds best to the user may indeed increase the burden of risk on the insurrer. In the long run all operators will have to pony up increased premiums if the insurrer is forced to accept unanticipated repair risks.

[Bolty McBolt]

Try that with your auto insurrance carrier some day


Fit a new (identical to the original, same weight and warranted) wing?

The wing is going to be fixed in situ in Singapore,

The pontiffs of this thread may argue the merits of this but this is the reality.
I would suggest the only thrashing out being done is who is paying the bill.

As to much of the theory regarding engine faults and vibration the cause.
I suggest you steer away from conspiracy and think incompetence the cause.
The recent oil leaks are from engines off the shop floor. Nil further leaks found after fleet wide torque check of oil tubes.

[Flapping_Madly]

Well BoltyMcBolt.Sir, in all the years I've been reading the stuff on the internet I've never seen a post stun so many others into silence so emphatically.

Those last three sentences of yours stunned me --no doubt.:uhoh:

[bearfoil]

flapping madly

The die is cast. The problem is well framed, in Regulatory action and in events of nature. The bottom line in revenue flight is to make money, and not kill too many people in its pursuit.

If, as Bolty implies, the entire TRENT issue folder is down to gremlins who cannot read a digital torque, then fair enough. Likewise if it is hungover bench monkeys with double vision who "counterbore" evil into the din.

We will see as events move along. Either the TRENT 900 can produce its touted power without shaking itself into bankruptcy, or it will fail. When 200 cycles loom nye, it will out what the Group has concocted so far as safety/profit.

It remains to be seen who values which side of the equation more.

"Safety is no Accident"

bear

[unmanned transport]

Was a torque wrench used during the installation of these hyd lines/B nuts ?
I doubt very much that one was used.

[FlightPathOBN]

Old Engineer, et al

The surface tear can be analyzed the same as any other opening in a continuous diaphragm..the opening must be able to distribute the forces around the opening.

The affected members at the 'opening', may need reinforcement to distribute, without wholesale replacement.

With the skin or diaphragm, that is a mere function of the fastening in regards to continuous, so perhaps a different fastener schedule about the affected area.

This event was an impact, so as long as there hasnt been deflection (bending) in the members, there can be no justification for replacement of the wing structure.

others comments..no, no, and no, a new wing is NOT required...if above.

You dont replace your arm if you have a cut.

[barit1]

unmanned transport:Was a torque wrench used during the installation of these hyd lines/B nuts ?
I doubt very much that one was used.

You may be interested to know that the B-nut fitting vendors acknowledge alternative tightening methods - other than the familiar torque system. I worked on an engine that used a wrench arc (http://www.tpub.com/content/aviationmaintandmisc/TM-1-1500-204-23-9/css/TM-1-1500-204-23-9_148.htm) method - and it was quite successful, after a bit of training of the knucklebuster crews.

[Landroger]

Before I first became a field engineer - forty years ago - I had to take a mechanical aptitude test and was then interviewed. His first and, as it turned out, only question was; "How much do you tighten a screw (or nut)?"

I thought about this for a moment and then gave the only answer I could think of;

"Enough."

I got the job. :)

Roger.

[unmanned transport]

barit 1, the question remains, was a torque wrench with current calibration used ?

Even more questions, if a torque wrench was not used, was the engineer familiar with the 'wrench arc' method ?
If he/she was familiar with that method, was it used on each B-nut that was disturbed? Was a leak check performed after the nuts were torqued?

[bearfoil]

Bolty would know...trust me.

[barit1]

I do not know what methods (torque, wrench arc, ...) are authorized in ATA100 pubs for Trent maintenance. And I won't speculate on whether a torque wrench was available/calibrated/properly used. Your question still stands.

[unmanned transport]

Yep, Bolty is our man.
Hey Bolty, you need to add a Y at the end of your Sirname.
Bolty McBolty ;)

[Trackmaster]

Some news on the repair plans for the aircarft.
No return to home base.

Qantas A380 engine failure | Repairs set to begin | $150 million bill (http://www.smh.com.au/travel/travel-news/repairs-to-damaged-qantas-a380-set-to-begin-20110317-1bxzv.html)

[Annex14]

I am more than only dissatified that this link was taken of this thread.
Four Corners - QF32 (http://www.abc.net.au/4corners/special_eds/20110328/qantas/)
It is the first foto sequence that shows more than the ATSB fotos do. E.G. it shows where the stub oil pipe was mounted and it shows in that blow up of the recovered IP disk segment that there is decouloration of the bore section - blueish signature -
This leads to two conclusions:
a. there was indeed an oil fire that weakened the disk and
b. the stub pipe broke probably by fatique
What immediately raises the question what caused that fatique failure ??
If I am not completely off track fatique failure is caused by intermittend loads. We also know by those graphs published in the ATSB report that oil pressure was decreasing from normal levels but stayed well above critical amounts, as was the quantity of oil available.
This once again very clearly indicates the total failure of that oil tube happened at the time the engine disintegrated and only the oil spelled through the fissure had accumulated enough of an amount to start that fire.
It is by no means identified in that report what really is the cause of the selfdestruction of the engine and subsequently almost the loss of QF 32. But typically it mentioned that 19 engines had received a "new module" and just that one that blew apart didn´t.
But I think by now every one that has had a closer look to the sequence of events has to come to the conclusion that vibrations of an unexpected amount has killed that engine. Though outside leakage that also is testimony of the last incident of a QF airbius flying to London on 3 engines.
I believe it is time to release those unknowns of the engine behaviour. It may hurt RR but it will give a safer operation of that engine / aircraft combination a chance.
I hope that RR is far beyond our imagination of whatneeds to be done.
Jo

[unmanned transport]

Mar 28, 2011

"A Four Corners investigation into last year's mid-air explosion of a Qantas A380 jet engine raises serious concerns about quality controls at Rolls-Royce.

It reveals the engine-maker was aware of a faulty weld on an oil pipe in one its Trent 900 engines a year before the explosion happened.

Despite the initial warning, the company went on to manufacture another faulty pipe.

The 2009 crack was caused by a sub-surface void which had been created in the welding process.

Three more oil pipes were found that were considered by regulators to fall outside the safety margin for thickness."

Rolls-Royce under scrutiny after Qantas explosion - ABC News (Australian Broadcasting Corporation) (http://www.abc.net.au/news/stories/2011/03/28/3175086.htm)

[kappa]

Some interesting updates about the fate of the Qantas A380 on this thread (http://www.pprune.org/dg-p-reporting-points/435797-a380-vh-oqa-write-off-5.html).

[Annex14]

I just found this report in "flightglobal"
Partial power loss on Qantas A380 caused by oil leak (http://www.flightglobal.com/articles/2011/05/18/356862/partial-power-loss-on-qantas-a380-caused-by-oil-leak.html)

I think of greatest importance is this sentence of the report
Quote:
The ATSB add that it is now conducting a "holistic investigation" into the oil leak and other reported cases of oil leaks in Trent 900 engines.

As I understand this announcement, ATSB has come to the conclusion that there has to be more behind these engine problems - QF 32 and others - than just oil feed pipes.
Jo

[lomapaseo]

Nothing New here

All Engine models leak oil sometimes. Where it leaks is important. Internally is important as it can ignite.

The problems with this engine are under close watch to ensure that corrective action is effective.

[vic_cairns]

"The Australian" newspaper writes today:
"Rolls-Royce was unable to tell how many more of its Airbus A380 engines might explode after last year's Qantas near-disaster near Singapore because of a lack of records."

see link:
Records missing on A380 engines | The Australian (http://www.theaustralian.com.au/news/nation/records-missing-on-a380-engines/story-e6frg6nf-1226058533710)

[bearfoil]

vic cairns

From the article, I see the minimum value for wall thickness of this stub pipe is .5mm. Can that be correct?? It is also the minimum "crest" measurement for the splines at IP shaft rigid coupling. The AD specifies a range for splines of 0.5mm to 2.65mm, so we know the AD is correct, but 0.5mm for an oil feed pipe? I think that is about 0.045 inch?

[archae86]

The interim report text calls out a (to me very minor) change in the diagnosed fatigue crack location of interest. This version is posted in the new interim report:
http://i6.photobucket.com/albums/y231/PeterAStoll/Aircraft/QF32/qf32_counter-bore_May2011rev.jpg
while this is the one provided late last year--downsampled by me to be a better match to the new and to be more suitable for posting here:
http://i6.photobucket.com/albums/y231/PeterAStoll/Aircraft/QF32/qf32_counter-bore_2010.jpg
Here is a link to the full resolution version from last year:
full resolution 2010 picture (http://i6.photobucket.com/albums/y231/PeterAStoll/Aircraft/QF32/counter-bore_large.jpg)
(depending on your browser and Photobucket, the high resolution one will display at less than full resolution when you click my link--the clue may be a plus sign in your mouse pointer--one more click will take you up to full res.

I'm not claiming this to be important--but it is new.

[Chu Chu]

Bear,

.5mm is a little less than .02". Even thinner than you thought.

[bearfoil]

archae86

It is extremely important. The smooth face is not indicative of either wear or fatigue, imo. For all we know that could be a keyway to accept a "c" ring, coupling m/f lines. It's tempting, but the "pipe" was done to exhaustion, so suffice that I still believe the "misalignment" is wear from excess vibration twixt male and female, not a blown end bore assignment. To add (edit), the length of the arrow indicating fatigue could be the limit of the metal as built. In other words, the smooth area defines the "former" position of the missing metal. That is oddball, and if I didn't know better, I would say that interpretation is misleading.......not to mention that the gouge at the end of the pipe mimics the limit of vibration. Note the "swirl" marks on the face of the injury? One might almost calculate the frequency of the damaging vibration from those telltales....

chuchu

Smokin' Eddie, that ain't too pretty much thick enough for oil, innit ?

bear

[Turbine D]

Bear,
The "new" area they now point out as the fatigue crack almost looks to me as a brittle failure (no ductility) rather than a fatigue failure, in other words, it just snapped due to lack of support of the rest of the structure that was progressively failing. I would have a tendency to agree with you relative to vibration.

TD

[bearfoil]

Hi TD...

This picture has always shown to me a coupling I have known as a "Quik-Couple". Male/Female, a sliding sleeve to align and retain the two mates. The "Misaligned counter bore" I have assumed is NOT a machining fault, but the result of a loose connection where the male, the counter-bored part is vibrating in the walls of the recipient.

A "counter bore" is the attaching piece, "counter" meaning mate. Its "misalignment" responsible for the sloughing off of wall material.

The striae on the walls show a vibration that likely blew off the large pieces, and in so doing, opened up the "cone" of play that caused the brittle fracture you speak of ?

[infrequentflyer789]

The "Misaligned counter bore" I have assumed is NOT a machining fault, but the result of a loose connection where the male, the counter-bored part is vibrating in the walls of the recipient.?

The investigation seems to view it as a manufacture fault, maybe they have other info that corroborates that view. If it is faulty to start with, then surely misalignment would result in a poor connection, which would then lead to more vibration of the connection, then leading to failure as you state. Or maybe cause and effect as you state. Chicken - egg.

Would be nice to have pictures of the whole pipe assembly - I still feel we're only looking at half (or less) of the picture.

[eagle farm]

Is there new information contained in this ATSB Interim Factual Update on 18 th May? Interested in expert comments.

Thanks



Abstract
The Australian Transport Safety Bureau is investigating an occurrence involving a Qantas A380 aircraft that experienced an uncontained engine failure over Batam Island, Indonesia on 4 November 2010. The aircraft landed safely in Singapore having returned with the aircraft's No 2 engine shut down. There were no injuries.
The investigation team has inspected the damaged engine and components and determined the sequence of events that led to the failure of the engine disc.
The investigation is also examining the airframe and systems damage that resulted from the engine disc burst to understand its effect on those systems and the impact on flight safety. That includes their effect on the aircraft’s handling and performance and on crew workload. A flight simulator program was used to conduct a number of tests in a certified A380 flight simulator. Analysis of the flight simulation test data is ongoing.
The investigation is continuing.
FACTUAL INFORMATION
Investigation update
The investigation team has developed into a large multi-agency group consisting of the Australian Transport Safety Bureau (ATSB) as the lead investigation agency with assistance from the French Bureau d’Enquêtes et d’Analyses (BEA), the Air Accident Investigation Branch of United Kingdom (UK AAIB), the Air Accident Investigation Bureau of Singapore (AAIB Singapore), the National Transport Safety Committee of Indonesia (NTSC), and advisors to the various investigation bodies from Rolls-Royce, Airbus, SAFRAN Sagem, Honeywell (USA and UK), Aerolec UK and Singapore Aero Engine Services Private Limited.
Regulatory action
Since the on-site phase of the investigation, the European Aviation Safety Agency (EASA) has facilitated a meeting between EASA, Rolls-Royce, Airbus and the Civil Aviation Safety Authority of Australia (CASA) with the ATSB, BEA and UK AAIB attending as observers. That meeting was to establish if the Rolls-Royce Trent 900 engine and the Airbus A380 airframe met the design certification requirements for the engine and airframe in light of the significant damage that resulted from this event. The engine manufacturer - Rolls-Royce - and the airframe manufacturer - Airbus - presented technical data and findings to that group. EASA and CASA agreed that, based on the information supplied, the airframe and engine meet the certification requirements. However, further investigation into the aircraft’s structure and systems and engine behaviour is continuing to fully understand this event and establish if there are safety issues that need to be addressed.
Disc failure
The ATSB, UK AAIB and Rolls-Royce have inspected the damaged engine and components
and determined the sequence of events that led to the failure of the engine disc. As a result of those findings, Rolls-Royce published a series of non-modification service bulletins (NMSB) with various amendments and a Service Bulletin (SB) to manage the continued serviceability of the Rolls Royce Trent 900 engine and EASA issued two Emergency Airworthiness Directives and one Airworthiness Directive. Qantas Airways initially placed operational restrictions on the Australian A380 fleet in conjunction with CASA. Commencing on 16 January 2011, those restrictions were progressively removed, as the fleet’s continued airworthiness was established.
The investigation has found that the intermediate pressure (IP) turbine disc failed as a result of an overspeed condition, liberating sections of the IP turbine disc that then penetrated the engine case and wing structure. The disc failure was initiated by a manufacturing defect in an oil feed pipe that resulted in a wall thickness reduction in an area that is machined to receive a coarse filter. That section of the oil feed pipe sustained a fatigue crack during engine operations that led to an internal engine oil fire that weakened the IP turbine disc. In turn, a circumferential fracture was induced around the disc, allowing it to separate from the IP turbine shaft. The unrestrained disc accelerated to critical burst speed. This led to the No 2 engine failure and subsequent significant penetration damage to the airframe structure and systems.
Since the ATSB’s Preliminary Report was issued, analysis of the oil feed pipe fracture surface has progressed and the investigation team has a better understanding of the failure mechanism. Technical reviews to date of the available evidence have established that the location of the fatigue cracking that was depicted in Figure 9 of the Preliminary Report1 is not the area of interest. The area of fatigue cracking and misaligned counter bore is now understood to be as shown in Figure 1 below.
Figure 1: Updated location of fatigue cracking

At the time of the accident, there were three oil feed pipe modification standards in the IP turbine module case (module 51) of Rolls-Royce Trent 900 engines. Oil feed pipe modules were manufactured to those modification standards as follows:
FW48020 standard modules, between October 2005 and May 2008 (42 units).
FW59326 standard modules, between July 2007 and March 2009 (67 units).
FW64481 standard modules, March 2009 and January 2011 (97 units).
　

As a result of this accident, Roll-Royce instigated the removal of Rolls-Royce Trent 900 engines from service with the following module 51 standards:
all FW48020 standard modules, which included the accident engine
10 FW59326 standard modules
one FW64481standard module.
　
A lack of measurement records for the FW48020 standard oil feed pipes meant that Rolls-Royce was unable to establish whether those oil feed pipes had been manufactured to specification. A subsequent risk assessment by Rolls-Royce determined that there should be a fleet wide removal of the FW48020 standard engines from service.
The measurement records for a number of FW59326 standard engines were also not available. An on-wing measurement technique identified seven of those modules with an oil feed pipe wall thicknesses of less than the Rolls-Royce stipulated minimum acceptance limit of 0.5 mm. Those engines were removed from service. In addition, three other FW59326 standard engines
1 See www.atsb.gov.au/media/2888854/ao-2010-089%20preliminary%20report.pdf (http://www.atsb.gov.au/media/2888854/ao-2010-089%20preliminary%20report.pdf)
- 2 - - 3 -
were removed from service after an evaluation of their manufacturing measurement records.
2 In Airbus products, the relationship between a flight crew order (or control input) and the aircraft response is termed a ‘flight control law’. The main objective of the normal control law is to provide instinctive and comfortable handling characteristics and comfort to those on board
Measurement records were available for all FW64481 standard module 51’s. However, the oil feed pipe wall thickness on one FW64481 standard module was found to be less than the minimum acceptable limit and that engine was removed from service.
The oil feed pipe wall thickness for all remaining Trent 900 engines in operation was found by Rolls-Royce to either meet or exceed the minimum acceptable manufacturing limit.
The ATSB, in conjunction with the UK AAIB and Rolls-Royce, is examining the circumstances and missed opportunities with the potential to have detected the reduced wall thickness and offset counter bore of the oil feed pipe prior to, during and after the manufacture of the module 51 assemblies. The ATSB is also reviewing the quality audits undertaken of, and the quality assurance system affecting, the module 51 design and manufacturing process and their effectiveness in detecting deficiencies in that process.
Aircraft response to the disc failure
The ATSB, in conjunction with Airbus, BEA and AAIB UK is also examining the airframe and systems damage that resulted from the engine disc burst to understand the effect on those systems and the impact on flight safety. That includes their effect on the aircraft’s handling and performance and on crew workload.
As part of the investigation, a flight simulator program was developed by Airbus from data that was obtained from the aircraft’s digital flight data recorder and cockpit voice recorder, from the aircraft’s fuel quantity management system, and from pilot interviews conducted by the investigation team. An A380 test pilot and group of experienced A380 flight crews from Airbus, the BEA and the ATSB conducted a number of tests using that simulator program in a certified A380 flight simulator at the Airbus facility in Toulouse, France. Those tests sought to establish the aircraft’s handling capabilities with the simulated damaged fuel transfer system, damaged flight controls and lift augmentation devices, and damaged electrics and electronic systems having effect. Various speeds and flight profiles were examined that simulated the workload that was experienced by the crew during the event. The simulation found that the aircraft had operated in ‘normal control law’2, in which, regardless of a flight crew’s input, computers prevent the exceedance of a predefined safe flight envelope. If there are certain types or combinations of failures within the flight control system or its components, the control law automatically changes to a different configuration level: alternate law or direct law.
Ongoing investigation activities

The investigation is continuing and will include:
the testing and analysis of the black-coloured soot residue that was found in the left wing internal (No 2) fuel tank.
additional analysis of the flight simulation test data
the examination of the airframe and systems damage that resulted from the engine disc failure
the ongoing review of the quality control and quality assurance system affecting the Trent 900 module 51 design and manufacturing process
analysis of the flight crew work load
the review of the aircraft’s maintenance, including engine workshop visits.
　
At the time of this update, the aircraft remained in Singapore, where repair schemes were being developed by Airbus and relevant components were being manufactured to facilitate that repair.
The gathering and compilation of the large amount of complex factual information is anticipated to be concluded by the end of July 2011. The analysis of that information and development and review of the investigation, including by directly involved parties in accordance with international protocols, is anticipated for completion by May 2012.

[Turbine D]

eagle farm,

As I read this interim update, there really is nothing new except for the correction made as to the area of fatigue in the photo of the fractured stub pipe. The report does give the focus of the ongoing investigation activities, most of which is focused on the aircraft, not the engine. The only engine activity is that concerning manufacturing and quality control related to the stub pipe failure at Rolls Royce.

So there isn't much more to say until the final report comes out, sometime in the future. The recommendations contained in the final report ought to be interesting.

TD

[bearfoil]

TurbineD

A final note on the updated "Stub Pipe" pic. The BEA merely seem to have chosen an alternate way to show the area of fatigue cracking. In the original, the line incorporates the actual area. In the follow up, it uses "limit line" id. Different way to show the same thing. ("Here is where the fatigue stops", etc.).

bear

[Turbine D]

Bear,

You could be right, I just never thought of it that way.

TD

[bearfoil]

TD

Did you ever look at that A330 (Singapore) "double bang" emer. return?

It seemed a bit similar to Qantas UF, then disappeared?

bear

[barit1]

While the corrective action relative to the oil fire (faulty pipe manufacture, etc.) is entirely appropriate, I hope that R-R doesn't stop there.

The fact that the T900 engine cannot survive a IP shaft disconnect is really disturbing to the turbomachinery folks I see often. I give you the RB211/744 failure QF74, 31 Aug 2010, KSFO (http://www.pprune.org/rumours-news/425863-qantas-emergency-return-ksfo-explosion-engine-6.html#post6025413) - the shaft broke, the IPT oversped, but it shed its blades before reaching burst speed. An uncontained failure (escaped turbine blade fragments), but with considerably less airframe damage.

[lomapaseo]

While the corrective action relative to the oil fire (faulty pipe manufacture, etc.) is entirely appropriate, I hope that R-R doesn't stop there.

The fact that the T900 engine cannot survive a IP shaft disconnect is really disturbing to the turbomachinery folks I see often. I give you the RB211/744 failure QF74, 31 Aug 2010, KSFO (http://www.pprune.org/rumours-news/425863-qantas-emergency-return-ksfo-explosion-engine-6.html#post6025413) - the shaft broke, the IPT oversped, but it shed its blades before reaching burst speed. An uncontained failure (escaped turbine blade fragments), but with considerably less airframe damage.


A couple of aggravating circumstances here

It may not have been just a pure overspeed failure. Given the coloration of the disk there may have been abnormally hot temperatures at the bore weakening it further than the shed speed of the blades.

The uniqueness of the IP module area may have prevented the massive tangling between blade airfoils and stator vane airfoils.

nevertheless the first priority corrective action should be against the massive oil leak that caused the shaft attachment failure in the first place.

[barit1]

It may not have been just a pure overspeed failure. Given the coloration of the disk there may have been abnormally hot temperatures at the bore weakening it further than the shed speed of the blades.

Yes, a sump fire is a nasty situation, but there appears to be a six-second interval between the shaft separation (evidenced by N2 IPC spooldown) and the IPT burst. Given the gas stream energy still available from N3, that unloaded IPT disc must have reached a very high speed.

The uniqueness of the IP module area may have prevented the massive tangling between blade airfoils and stator vane airfoils.

I perceive a lack of "what if" planning. The detached disk drifted aft until it contacted some static structure (mid frame) and established what designers call a "false bearing", which had low enough friction to permit the disc to continue accelerating. There were no static nozzle guide vanes to clash with turbine blades, thus destroying the driving torque; the blades remained attached as the disk kept accelerating; and the next part to fail was THE DISK ITSELF.

So at least two opportunities to survive the sump fire were lost IN THE DESIGN PROCESS.

Edit: On second thought, I wish to change the word "survive" in the last sentence to "mitigate".

[Bill Harris]

She's on her way back home...

Qantas A380 blowout plane returns to service

By Harry SuhartonoPosted 2012/04/21 at 1:40 pm EDT

SINGAPORE, Apr. 21, 2012 (Reuters) — Australia's Qantas took its repaired A380 superjumbo back to the skies on Saturday, resuming a 3,900 mile journey dramatically interrupted 18 months ago when one of its engines blew up over Indonesia.

After $140 million of repairs, the world's largest jetliner took off for Sydney shortly before midnight, carrying Qantas Chief Executive Alan Joyce and members of the crew that safely landed the crippled Airbus in Singapore with 440 passengers on board.

"She's running a little late... 18 months," Joyce earlier told reporters under the left wing of the big jet, which was sprayed by shrapnel as the engine blew apart shortly after take-off from Singapore in November 2010.

NewsDaily: Qantas A380 blowout plane returns to service (http://www.newsdaily.com/stories/bre83k0e1-us-qantas-a380/):)

--Bill

[Kucing]

pardon me for asking this..

but.. I really need to know what action(s) have been taken in light of this engine failure?

From what I know, the problems only affects those A380 with RRoyce Engines correct?

I'm due to travel with Singapore Airlines soon.. transatlantic flight to LA, USA..
I believe all SQ's A380's are fitted with RRoyce engines..

This kinda make me wary..

I have the option of flying with another airline.. they use B777-300ER for route to LA,USA..

I am rather confused now... go with SQ a380 or shall i just go with B777-300ER :)

any comments appreciated! Thx

[Bergerie1]

Kucing

I wouldn't worry if I were you. This particular problem will have been examined to the Nth degree.

Turbine disc failures are very rare and have happened to most (if not all) large engines, not just Rolls Royce. It is even more unlikely to happen again now after all the work that has been done.

Just take the most convenient flight and enjoy it!

[barit1]

To be quite clear about QF32 and similar failures:

In ANY multispool engine, IF the high-pressure spool keeps running after a shaft separation of (one of) the lower-pressure spools, that low-pressure turbine will be driven to an overspeed condition.

Thereupon, one of perhaps three things will occur:

1) The turbine blades will, by design or accident, suffer a blade root failure. This creates medium-energy shrapnel, but also removes the driving torque from the free disc, so it can coast to a stop without further failure. eg QF74, SFO 744, RB211 engines.

2) If 1) doesn't happen, the free disc assembly will be driven aft where the blades will contact static parts such as a downstream nozzle guide vane ring; this will beat up the airfoils to the point that the disc stops accelerating. I have seen CF6 failures of this type.

3) if 2) doesn't happen, then the disc may continue accelerating to the point that it bursts. I give you QF32, Trent 900 - and also perhaps the T1000 test bench failure a few weeks before QF74.

Turbomachinery designers must take shaft failure into account in the design process. Some may do a better job than others.

[Turbine D]

barit1,

Good post!:ok:

I completely agree with what you said, it's all in the design...

Regards,

TD

[lomapaseo]

Than there is the problem of too much oil leakage and resulting fire overheating the disk and it's attachment shaft to the point of burst before it even has a chance to move aft.

Thus the fix is to minimize a short term oil leak of this magnitude.

Obviously a lesson for all manufacturers in their quality control efforts.

[barit1]

lomapaseo:Thus the fix is to minimize a short term oil leak of this magnitude.

Yeah, that will address this particular failure sequence (overheated disc flange).

But decades of experience says there are potentially other causes for shaft separation, and the fundamental issue is the lack of any provision in the Trent to destroy the runaway turbine airfoils prior to disc burst.

I will grant that the six-second interval between N2 compressor spooldown and N2 turbine burst might yield promise for a software fix >> namely, fuel cutoff if sensed N2 is too far out of whack.

[lomapaseo]

Barit1

But decades of experience says there are potentially other causes for shaft separation, and the fundamental issue is the lack of any provision in the Trent to destroy the runaway turbine airfoils prior to disc burst.



I doubt that the regulators will agree with that

Do any of the manufacturers altually demonstrate a shaft separation at takeoof conditions, or do they just point at some design feature that might have worked in the past?

As in all accidents there are lessons to be learned by all

[Turbine D]

lomapaseo,

Do any of the manufacturers altually demonstrate a shaft separation at takeoof conditions, or do they just point at some design feature that might have worked in the past?

What you do is understand this is a possibility, and you design so that if the power drive arm would fracture releasing the turbine wheel from the shaft, it would not reach an overspeed condition where the disc would come apart. Although this was done on previous Trent engines, it wasn't done on this engine. It wasn't a lesson learned, it was a lesson forgotten, simple as that. You don't have to demonstrate it, you just use experience and good common sense to prevent it.

TD

[lomapaseo]

You don't have to demonstrate it, you just use experience and good common sense to prevent it.



So if you've never seen it in a model series it's good common sense

but once it happens it's an oops

[barit1]

Good design practice requires a failure modes / criticality analysis (FMECA), and a good analysis will consider historical known failure types. Not just those required by regulators, but ones that (for example) could taint the reputation of the product or the company.

For example, a modern propeller design incorporated features that lost sight of lessons learned over 6 or 7 decades. As a result, a regional airliner augured in 20 years ago. Neither the designers nor the FAA had retained the corporate wisdom to prevent the design error. :ouch:

[Lyman]

barit1

The LP shaft by observation incurred no visible injury from the burst of the IPT. The HP shaft, nested withn the Drive Arm "Bell" is not seen. The third shaft of three, The Ishaft, terminates in a cylinder, the "Bell". Would you have any comment as to the vulnerability of this "Bell" to harmonic vibrations produced by the nested pair, and possible "whip" of this assembly, due wear of splines more forward of the IPT case? Considering the vibratory result can be multiplied through the length of the IP/HP shaft pair as it progresses aft, and in a super heated environment, would mechanical disruption play an important part in the burst (not to diminish the effects of "oil fire").

N speeds are not available at the time (per design) to effect a fuel cut. Instead, when N2/N1 values are rejected, the ECM recieives an NCD re: N3, and a value is providied that is 'theorized' by the Engine computer. (as I understand it). This allows the HP to soldier on, at least for six seconds?

regards

[barit1]

Lyman:

By use of the term "shaft failure" I mean the functional disconnect of the IPC from the IPT, regardless of the specific location of the break. The IPT drive arm is one component of the shafting. You can theorize all day long about vibration, shaft harmonics, etc. but these are merely possible logical routes to the ultimate shaft disconnect.

Good design practice assumes that the shaft will, despite all your efforts, suffer a failure someday; and it's the designer's job to mitigate the failure.

And yes, I know that R-R N2 sensing is at the compressor end, so there's no hard data from the IPT itself if a disconnect happens. But the observed N2 spooldown is non-characteristic when the other rotors are still up to speed, and should be interpreted as the signature of a shaft failure, IMHO.

[Lyman]

I am trying to build on what is (was) known at the time. The AD warned specifically of aftward axial transit of a shaft, causing damage to the a/c, and those on the ground (sic). The wear, specific to the AD, was located at the splines forward of the IPT (at the other end of its shaft), and reporting of the initilal exam of the engne contents stated "Rigid Couling Failure". Rigid coupling failure was reported as the cause, not the result. The "Burst" was an artifact of the failure of the Bell, (Drive Arm), not the cause of the uncontained failure. Now it's possible to chiicken/egg this, but I am aware of the Rigid couple demise as the cause of the problem, and the couple disintegrated due, What? I don't think the couple would fail from heat, nor vibration alone. I also sense that the consensus here is that the wheel failed "first". i think that is wrong, from a read of the report. It is also inconsistent from the previous failure, (Miami), where the wheel failed from migration, not oil fire. imo.


For instance, couldn't the N2 spool down have been caused by the contact with the web? The actual friction and resistance slowing the shaft and puddling the "false bearing"? This while the shaft/turbine maintained its integrity, until the rigid coupling lost the Wheel?

your thoughts?

[Turbine D]

Lyman,

I am trying to build on what is (was) known at the time. The AD warned specifically of aftward axial transit of a shaft, causing damage to the a/c, and those on the ground (sic). The wear, specific to the AD, was located at the splines forward of the IPT (at the other end of its shaft), and reporting of the initilal exam of the engne contents stated "Rigid Couling Failure".


We have been through this many times. This engine had been inspected and passed the spline wear requirements before being placed back in service. The rigid coupling of the IP shaft, located in the compressor section of the engine, did not fail. The IP shaft did not move rearward. The initiation of the failure event started with an oil leak in a compartment just forward of the IP Turbine disk. A fire started as this area is hot. The fire caused the IP turbine disk to begin to heat above temperature capability of the disk alloy and rotational stresses being encountered at the time. Now to understand what happened next, you have to understand the metallurgy of superalloys used in disks.

The best disk superalloys have an operating temperature of between 1200℉ and 1400℉. These alloys have good ductility and creep rupture capabilities within operating temperature ranges. If the temperature is exceeded, creep and in the case of a spinning disk, outward growth (stretching) will occur fairly rapidly. As the stages of creep progress, the final stage progresses to failure very rapidly. So lets apply this to the IP disk in question.

The IP disk is attached to the turbine end of the IP shaft by a series of circumferential bolts which secure the power drive arm of the IP disk to the shaft. The designers determine the thickness of the power drive arm, the web thickness of the disk and the disk bore mass based on anticipated stress levels and temperatures during engine operations throughout the flight envelope plus a safety margin to preclude disk burst. So what happens when an oil fire develops in the compartment just forward but adjacent to the IP disk? The disk begins to overheat from the bore to the disk web with the overheating commencing from the forward side of the disk. As the temperature begins to exceed the superalloy capability, the disk begins to stretch somewhat unevenly from front to rear, but radially. But, the power drive arm is firmly attached to the end of the shaft. As the stress limits begin to be exceeded, the power drive arm fails, releasing the disk and the disk is free to rotate with no control over rotational speed. As the rotational speed increases with no impediment to slow it, it bursts. That, I believe, is what happened on this engine.

Regards,

TD

[barit1]

While I don't have details at hand, Lyman may be referring to the RB211 failure (QF74, SFO 8/2010) in which turbine shaft splines were wiped.

[Lyman]

Hi Turbine D

Here... As the stress limits begin to be exceeded, the power drive arm fails, releasing the disk and the disk is free to rotate with no control over rotational speed. As the rotational speed increases with no impediment to slow it, it bursts. That, I believe, is what happened on this engine.

I think you are missing something, and it is key to my description of the failure. Using your own description, above, when the Disk is released, it has not the time to increase in rotational velocity. None.

The very instant it is released, it wobbles wildly out of control,, no longer restrained by a symmetric join. It contacts the case, wobbles forward and aftward, and begins immediately to SLOW. It is converting what was controlled and productive rotation into chaotic and catastrophic disintegration of the IPT cave, bursting the case.This is the mechanical Bang. The second bang is the release of P30 gases into the atmosphere, possibly.

Again, once released, it goes non planar and is free to eccentrically smash everything in its path, for a VERY short time, constrained in a Titanium "Barrrel".


There is no overspeed. Out of control rotation, along with the eccentric "orbit" of the disc, shears the blades, and initiates the tri-partite decomposition of the Disc. Failure at the IPT/Drive Arm it was, as reported by Rolls.

What say you, my friend?

[Lyman]

barit1

To continue, is it possible that the six seconds of N2 spool drop are connected to the loss of the rigid joint at IPT/Drive ARM? Is the IPT slowing, and converting its energy into a disruption of the contents of the IPT cave? Without the obstacle of the Turbine, is the pressure stage increasing rapidly in pressure, since there is no mechanism to transmit it to the LPT? The HP is still functional (and gains rpm, and 'added' fuel, sent by the ECM, to make up for the loss of the IPT 'barrier').

I don't think it happened that way, the IPT, in circling the case, cannot have stayed for six seconds?

[Turbine D]

What say you, my friend?

I have given you my thoughts, there is nothing more to add....

TD

[Lyman]

I should have asked my question more directly. Once separated from the Power Arm, how can the Disk possibly retain stability sufficient to gain rpm? Won't it start going bs on its cramped environs?

Sorry for the obtuseness, Turbine D.

respect

[barit1]

Wobbling? What is the source of the force required to start it wobbling? Have you ever contemplated the magnitude of force required to accomplish this with a 100kg disc turning 7000 rpm?

Or have you been reading too much Velikowsky? (http://en.wikipedia.org/wiki/Worlds_in_Collision)

[Turbine D]

Lyman,

I should have asked my question more directly. Once separated from the Power Arm, how can the Disk possibly retain stability sufficient to gain rpm? Won't it start going bs on its cramped environs?

Do you realize that if you stand in front of a turbofan engine and grasp one of the fan blades with your little finger you can, with very, very little effort at all, turn the fan over, which in turn, turns the LP compressor and the LP turbine? It is a jewel and the same is true with a triple spool engine. So when you think about that, think of what happens in the IP turbine on the Trent 900 when the disk separates from the shaft holding it. We are talking here no more than a couple of seconds. Your talking as if we are in slow motion. The turbine wheel, once the power drive arm fractured, over sped very, very quickly. The thing driving it was the highly hot compressed air that was expanding, but passing through its turbine blades, still attached to the disk. Remember the aircraft was in the climb mode. The rotational inertia for the given mass is unbelievable in this situation, The turbine wheel was driving nothing, a free turbine is a nightmare. Additionally, there was nothing in the way to stop it, it just proceeded to burst and that is what the photos of the found disk fragment depicted.

I would suggest you, once again, look at the engine cross section and note if it moved rearward, there was no substantial material to decrease it rotational speed except for the inner flow path band of the stage 1 LPT nozzle. Whether it wobbled or not is immaterial, in fact it may have gained enough rotational speed while still in place over the IP shaft, but free of the shaft to initiate the speed leading to final failure. Remember, there was little damage to the LP turbine except for the stage 1 LPT nozzle. The majority of debris went outward in a radial direction, not rearward.

Think real time, not slow motion time which is only recorded by high speed cameras.

TD

[barit1]

There is another aspect to this, and that is the rate of heat transfer from the oil fire. Lightweight components heat up very quickly, but massive structures much more slowly. The IP rotor disc is a composite of massive areas (the disc bore) and much thinner areas (the drive arm). Therefore I suspect the drive arm overheated much more quickly than the disc proper.

This reinforces the scenario in which the drive arm failed first (after the oil fire escaped the sump). This released the disc assembly, blades included, and since it was subject to a big gas pressure load on the front face, it was immediately blown aft until it was seated on some static parts, establishing a "false bearing". It's still turning 7000 rpm, and the false bearing is quickly friction-heated producing liquid metal, which has some lubricating properties.

And it's still being driven by core turbine exhaust airflow, and it has lost the normal torque load of the IP compressor.

Guaranteed overspeed, as previously stated.

[Lyman]

TD: " The rotational inertia for the given mass is unbelievable in this situation, The turbine wheel was driving nothing, a free turbine is a nightmare. Additionally, there was nothing in the way to stop it, it just proceeded to burst and that is what the photos of the found disk fragment depicted."

That is my point. I think from Edelweiss, and evidence at LPT#1, there was no time for the debris to blow aft. It exited out the opening created by the departing blades, followed immediately by the three main, and hundreds of minor, bits of the disintegrated wheel. If we consider that the wheel, to gain rpm, needed time on shaft (or, 'false bearing'), then debris would have exited back through the LPT proper, making a proper mess. As the wheel was blown instantly back against the Stator vanes platform, the IP blades were shorn, and blew out the case, co-planar with rotational orbit. This is what happened to Edelweiss; in that case, the IPT remained attached (though 'fractured', circumferentially).

Consider, the IPT is not attached to the shaft, per se, and a loss of the drive arm leaves a discrepancy bore diameter/shaft of many centimeters. The bearing is ad hoc, and unable to support rotation. The IPT orbit is instantly eccentric, and the disintegration is likewise instantaneous. It is the relatively undamaged condition of the LP turbine that gives this away; all debris blew out simultaneous loss of drive arm, imho. Similarly, the IPT blades were lost instantly, nothing remained to transmit the gas flow into additional rotation. This is Edelweiss, redux, save IPT loss out the case. Only in Edelweiss, the fracture of the drive arm was not complete, and the wheel was luckily retained.

I know you are convinced of oversped wheel; without blades, and time, I cannot agree. 7000 rpm is well sufficient to blow up the IP system. Is there a conclusion in the report? The initial used the word "may" re: overspeed.

add; [B][Remember, there was little damage to the LP turbine except for the stage 1 LPT nozzle. The majority of debris went outward in a radial direction, not rearward. /B]

Yes, again, my point. Even two seconds would have seen a substantial flow of debris out the tail pipe. Radial exit of virtually all the debris drives my conclusion that the disintegration/exit was instantaneous, not lingering.

For N2 to spool down whilst the IPT was spinning up for seconds, and there is light damage to aft rotational mass, is a reach, imo. What is more likely is a damage trail suggested by the actual AD on this engine. Aft drift of the IP shaft, metal/metal contact, superheated Drive arm, and disintegration, causing aircraft damage and parts on the ground, endangering people below. The AD was written with climb out in mind, hence the reference to population underneath. The 380 serves airports in populated regions, and catastrophic failure puts those below it at risk.

The source of the wear on the rigid coupling is published, and the damage pursuant is also. Drifted shaft, and oil fire are two results of the cause of the AD in the first place. Loss of oil is reported on many a/c, along with oil pressure problems, and preceding incidents.

If the cause of the problem was overspeed, fine; it is not necessary to the explosion, however, and that is my point. I don't see evidence of any kind that isolates this uncontained failure from one predicted by the regulator. For some reason, it has become necessary to propose a new, and unrelated anomaly. Why is that? (Rhetorical). The oil pipe problem was not new, it was not unrelated, and it is not logical to separate the "Oil Fire" from the AD. The wear was caused by vibration of the the Rotating Mass. imho

Thanks

[barit1]

Lyman, I wish you would consider the fact that turbine discs don't just fail at near-normal rpms, absent some significant manufacturing defect. I point to the eight engines intentionally crashed on 9/11. All the turbine discs, from (I believe) three different manufacturers, remained in one piece after the dust had settled. There are plenty of other accidents available for study in which the impact forces failed to break the turbine discs.

Consider also that the IPT on this engine generates (I'm estimating here) 50,000 shaft horsepower, all of which is delivered to the IPC. If the shafting (drive arm in this case) lets go, it's like tromping on the clutch and accelerator at the same time.

No, the only things that I'm aware to cause disc failure are overspeed, overtemperature, or a fault in the disc (either during forging, machining, or some repair process). For you to propose otherwise for QF32 will take some very serious analysis.

[Lyman]

Hi barit1, thanks for the reply. I think there is merit to what you say, without doubt, these rotors are phenomenally strong. The design consideration is strictly that to which you allude, resistant to overspeed and overtemp, to a point. We do not need to look past the existing data to find failure. In fact, the failure was foretold by no less than the regulating authority, to which the engine manufacturer is entirely responsible for proof of quality. So I do not feel the need to go beyond, the failure is in front of us.

Let's assume that some combination of above limit rpm and ambient temp caused failure, fair enough?

My purpose from the outset is to frame the evidence within the data provided in the AD as enforced. If some mechanism failed the connection other than high heat, or overspeed, let's agree it is not present in the analysis? I think the metallic spatter is the product of friction stir at the arm/engine frame, as predicted by EASA. Only one quart of oil was missing, the fire was in front of the wheel, and the prediction via EASA tend to override a lingering spin up whilst the core is melting. The Drive Arm, logically was the last failure before disintegration, and the decomposition happened instantly. For the spatter to appear on the aft face of the wheel speaks against the heat migrating from its front? Yet with a shaft transiting aft, the friction can create instant molten metal, whilst the shaft retains integrity. You cite the N2 loss of rpm, I think that was a result of metal/metal from shaft, case, as predicted. I would say the shaft slowed whilst joined to the Turbine, and EEC poured extra fuel in to compensate for the reduction in power applied to the melting metal in the core.

These are informed from the AD, directly. How can N2 unwind for seconds, as a result of separation of IPT? Again, the IPT without the Drive Arm connection is a sizable herd of horses loose in the barrel. The Orbit would have to remain precisely free of obstruction for the Wheel to accelerate. The Drive Arm/IPT resemble a Bell on a bearing at the small end. If the connection is lost, the mass is not only free to wander, chaotically, but the rim of the Bell is quite distant from the bearing attach, any imbalance would instantaneously throw the entire asembly into an extreme eccentric.

I am not arguing for its own sake, but am trying to fit the results into the predictive regulation published by the engineers before the fact.

See you in JB?

take care, and thanks again, I appreciate your patience with my stubborn streak.

[Bergerie1]

Kucing,

You sent me a private message, but unfortunately the website won't let me reply to you. If you send me another private message with your email address I will try to answer your queries.

[Turbine D]

Lyman,

My purpose from the outset is to frame the evidence within the data provided in the AD as enforced. If some mechanism failed the connection other than high heat, or overspeed, let's agree it is not present in the analysis? I think the metallic spatter is the product of friction stir at the arm/engine frame, as predicted by EASA.

Lets go through some facts again.

From the latest ATSB Interim-factual Report:

"The investigation has found that the intermediate pressure (IP) turbine disc failed as a result of an overspeed condition, liberating sections of the IP turbine disc that then penetrated the engine case and wing structure. The disc failure was initiated by a manufacturing defect in an oil feed pipe that resulted in a wall thickness reduction in an area that is machined to receive a coarse filter. That section of the oil feed pipe sustained a fatigue crack during engine operations that lead to an internal engine oil fire that weakened the IP turbine disc. In turn, a circumferential fracture was induced around the disc, allowing it to separate from the IP turbine shaft. The unrestrained disc accelerated to critical burst speed. This lead to the No 2 engine failure and subsequent significant penetration damage to the airframe structure and systems."

Your quotes directed to barit1:

You cite the N2 loss of rpm, I think that was a result of metal/metal from shaft, case, as predicted. I would say the shaft slowed whilst joined to the Turbine, and EEC poured extra fuel in to compensate for the reduction in power applied to the melting metal in the core.

These are informed from the AD, directly. How can N2 unwind for seconds, as a result of separation of IPT? Again, the IPT without the Drive Arm connection is a sizable herd of horses loose in the barrel. The Orbit would have to remain precisely free of obstruction for the Wheel to accelerate.

The way a three spool turbine engine works is this:

1. The low pressure turbine (LPT) drives the fan and low pressure compressor.
2. The intermediate turbine (IP) drives the intermediate compressor.
3. The high pressure turbine (HPT) drives the high pressure compressor.

So, if the IP turbine disconnects from the shaft resulting from a circumferential fracture of the power drive arm, it is no longer driving the intermediate compressor. Therefore, N2, that is measured at the intermediate compressor begins to decrease, in this case from 94.5% to 93.2% at UTC 0201:00. A 100% speed for the IP turbine rotor means it was rotating at 8,300 RPMs. At 94.5% speed it is rotating at 7844 RPMs. Burst speed would be approximately 10,375 RPMs, assuming a 25% margin above maximum operating RPMs. It didn't have to speed up (overspeed) very far to get to the burst point. The rate of speed up would be determined by the expanding air passing through the IP turbine blades received from the HPT blades. It was probably less than 7 seconds from normal operation to burst.

The Drive Arm/IPT resemble a Bell on a bearing at the small end. If the connection is lost, the mass is not only free to wander, chaotically, but the rim of the Bell is quite distant from the bearing attach, any imbalance would instantaneously throw the entire asembly into an extreme eccentric.

No it doesn't. It only resembles that way on the disc after the failure. Prior to failure, it is a bent downward plate (towards the engine centerline), parallel to the disc face, a circumferential feature that attaches to the end of the shaft by means of a series of bolts that pass through bolt holes in the power drive arm.

If the connection is lost, the mass is not only free to wander, chaotically, but the rim of the Bell is quite distant from the bearing attach, any imbalance would instantaneously throw the entire asembly into an extreme eccentric.

The mass you suggest, the IP turbine rotor disc and blades attached is free to very rapidly accelerate until such time the disc bore stretches which is indicative of pending failure and then moves back. At that point, IMO, the only contact would be near the base of the turbine blades embedded in the disc slots contacting the stage 1 LPT nozzle. That rubbing would create metal splatter observed on the aft surfaces of the disc, similar to what happens during an inertia welding process, an initial false bearing without adequate pressure to slow the rotation of the disc. It was not chaotic at all until the burst occurred. Again, IMO, eccentric motion had little effect on what was about to happen.

[lomapaseo]

about as chaotic as a freely spinning bicycle wheel being dropped from a window ledge or ladder

Try it some time and film it before it hits the ground

[Lyman]

I suggest that once the circumferential fracture separated the wheel from the power arm, the disc was already exceeding a (somewhat lower) burst speed.

Are we looking at the same schematic? The turbine disc has "return" (sleeve) feature that is the drive arm. The circumferential fracture separated the wheel from the arm, therefore the wheel is no longer restrained in a circular orbit. Show me where the wheel has any interest whatsoever in accelerating? The massive pressure of the exiting HPC gases thrusts the wheel instantly into the LPT Stator. The turbine blades are sheared, and the wheel performs a very rapid eccentric dance out the case, post disintegration. Attached to nothing, how do you say the wheel remains stable to resist the flow of gas, and thus accel? It has no axle. No stability.

Lomapaseo. A rapidly spinning bicycle wheel illustrates exactly my point, its gyro expression of high energy slams it into the stationery parts of the core.

I still suggest that the slowing of the IPC demonstrates the axial migration of the IShaft aft ward into the "stationery parts of the engine" (AD). Integrity of the shaft is required until disintegration of the I Turbine, IMO. I suggest that this slowing of N2 (evidence from phonic wheel, and diminished pressure), is what precipitated the introduction of extra fuel into the burners, and caused N3 to increase, perhaps even introducing unburned Fuel into the IP cavity. That can't be a good thing...

How did one quart of oil incinerate this engine?

[barit1]

Show me where the wheel has any interest whatsoever in accelerating? The massive pressure of the exiting HPC gases thrusts the wheel instantly into the LPT Stator. The turbine blades are sheared, and the wheel performs a very rapid eccentric dance out the case, post disintegration.

Sorry, but in the T900 series, the space downstream of the IPT is vacant for quite some distance; The LPT stator (if any **) is well downstream. The IPT blades remained largely intact, providing the "unbalanced torque" (i.e. freewheeling, unloaded) to accelerate the disc to burst speed.

NOTE ** One aerodynamic improvement in the Trent engine is the use of contra-rotating spools. I do not recall positively which ones rotate opposite to others, but I think the IP and LP are opposite. IF this is the case, R-R had the opportunity to ELIMINATE the first stage LPT stator, because the swirl flow upon leaving the IPT accomplishes the same thing. Less weight, less pressure drop, better efficiency, but also the increased opportunity for an IPT overspeed per the present discussion.

[Turbine D]

Lyman,

Your quote:
I still suggest that the slowing of the IPC demonstrates the axial migration of the IShaft aft ward into the "stationery parts of the engine" (AD). Integrity of the shaft is required until disintegration of the I Turbine, IMO.

Again, from the ATSB Interim Factual Report

The investigation has found that the intermediate pressure (IP) turbine disc failed as a result of an overspeed condition, liberating sections of the IP turbine disc that then penetrated the engine case and wing structure. The disc failure was initiated by a manufacturing defect in an oil feed pipe that resulted in a wall thickness reduction in an area that is machined to receive a coarse filter. That section of the oil feed pipe sustained a fatigue crack during engine operations that lead to an internal engine oil fire that weakened the IP turbine disc. In turn, a circumferential fracture was induced around the disc, allowing it to separate from the IP turbine shaft. The unrestrained disc accelerated to critical burst speed. This lead to the No 2 engine failure and subsequent significant penetration damage to the airframe structure and systems.


Quite honestly, I never saw this report until yesterday. It describes what I have thought and tried to express to you all along. However, you believe differently with no evidence to support your theories. So it remains a standoff, your theories verses factual information and some turbine engine experiences on my part. No sense in continuation of this discussion.

How did one quart of oil incinerate this engine?

Simple, it started a fire in a very sensitive area of the engine that generated heat on top of what was already present, which when combined, exceeded the disc material capability for the temperature experienced.

[Turbine D]

Hi barit1,

On the Trent 900 engine, the LP & IP rotors turn counter clockwise with the HP rotor turning clockwise. This enables elimination of the stationary nozzle between the HPT blade wheel and the IPT blade wheel. The only thing between the two is a sheet metal frame structure that contained the failed oil feed pipe that started the fire. The stage 1 LPT nozzle is still there, but has a significantly larger diameter due to the conical nature of the LPT.

[Lyman]

Hi barit1 I think it is HPC that spins contra. The HP shaft is nested inside the well of the IP shaft and the bearings for each have a ~20000 rpm differential due rotation opposition.

TD: From the schematic, the bearings for the aft terminus of the IP shaft are on the shaft side, the Power Arm is outboard of the shaft's end, as it returns foreward, surrounding the bearings. Thus any separation of the Power Arm from the wheel eliminates the cvarriage for the Turbine Disc, via separation, The Disc has no structure left, it is not as if the wheel is inboard, and merely spins on, without bearings.

I have read the report, and it can be read in at least two ways, leaving unclear some of the evidence/conclusion chain of thought.

I have spent hours reviewing the schematic, and to me, it is simple. I might be missing some element, or the drawing may be incomplete or inaccurate. The mate for the Power Arm, Wheel, Shaft, and bearing is in the three lam sandwich at the most aft end of the shaft. If these retaining bolts sheared, the entire Arm/assembly is lost, there is no possibility for any retention of the Wheel's mass for any length of time.

Could you post the Drawing? I have limited computer skill, and perhaps if addressing the same drawing, we could meet in our thoughts? I don't doubt either of you gents, and am in deep water with you two, my mechanical skill is better than my theoretical, and I stand to be corrected, always....

[Turbine D]

Lyman,

The innermost shaft is the LP, the outermost is the HP and IP shaft is between the HP & LP. The bearing supporting the HP rotors are separate (independent) from the IP rotors.

The IP disc accelerated to burst while still over at least part of the two rear roller bearings.

I don't see how you can read the ATSB Report two ways...

[barit1]

Lyman & Turbine D:On the Trent 900 engine, the LP & IP rotors turn counter clockwise with the HP rotor turning clockwise.

Thank you for reconnecting my aging neurons! My argument stands amended.

[barit1]

Lyman:...any separation of the Power Arm from the wheel eliminates the cvarriage for the Turbine Disc, via separation, The Disc has no structure left, it is not as if the wheel is inboard, and merely spins on, without bearings.

I assure you that the intact disc (minus the drive arm flange) is only unsupported for a few milliseconds, as the gas pressure drives it aft to a false bearing surface in the LPT inner duct. Now it is once again supported against a fairly low-friction surface, akin to the thrust bearing on your car's crankshaft against which your clutch reacts.

Without a significant torque load (normally the IPC, which is now un-driven and winding down), the IPT has no chance to do anything other than spin up to destruction. Over the decades, I have seen the results of like turbine disconnects; the sequence is always fairly similar, and the results never pretty.

You seem to keep referring to the IP main shaft, but is there any mention of a pertinent shaft defect in this accident report?

[Lyman]

You seem to keep referring to the IP main shaft, but is there any mention of a pertinent shaft defect in this accident report?....

************************************************************ ***

No, but I am not sure of the direction you want to go. The Shaft did not fail, at least not prior to disintegration. If you look at the section through this space, you see that the Turbine Plane is foreward of the aft bearing (shaft). The attach to the shaft is aft of the bearing plane. So the wheel is connected via a bearing that is remote from its geometrical plane involving a 180 degree return to the Drive Arm. I assume the circumferential fracture is located at the seam between wheel and ARM. The bore of the Wheel at that point is the same diameter as the ARM, does the Wheel slip over the ARM, as it moves "AFT"? Nice trick! Or does it slam into the Stator platform (LPT) which provides some false bearing support? OR, is the circumferential fracture at the aft terminus of the ARM, where it flats to enter the three way join? If the true bearing architecture gives way to a new and "false" support, where is it located? On the Stator? This surface is of course irregular, ad hoc, and incapable of maintaining tolerance that prevent the Wheel from going wildly eccentric, here's why: The bore of the IPT is much larger than the diameter of the IShaft, of course. Unlike a standard slip fit or "Press Join" to an axle (with a keyway, or splines) and without restraint, the wheel cannot maintain any local integrity....

I have searched for the proper schematic, and the usual places are not available, so I do hope I am not remembering the T5, or 7.... So my words are memory based. Bottom line? Can you help me with a better description of this "false bearing". Also, how do the blades remain attached , my opinion is they exited forward as they were pushed out the pine trees by the stator?

[barit1]

While i have seen an (alleged) cross-section of the T900, I cannot seem to locate it just now. Maybe someone can post a link so I can point out the pertinent features.

But the essential point I'm making is that the uncoupled disc assembly will establish a false bearing INBOARD of the IPT airfoils, so they will remain in place as the disc assembly is driven overspeed.

[Lyman]

post 1415 previous thread, looking

[Turbine D]

Lyman,

I only mention the IP shaft because you think it move rearward, somehow separating from the coupling in the compressor section. It did not!

Your quotes:
Yet with a shaft transiting aft, the friction can create instant molten metal, whilst the shaft retains integrity
And,

I still suggest that the slowing of the IPC demonstrates the axial migration of the IShaft aft ward into the "stationery parts of the engine" (AD). Integrity of the shaft is required until disintegration of the I Turbine, IMO.

The IP disc is a smooth bore disc. It fits snuggly around the end of the IP shaft and is held in place by a series of bolts through bolt holes in the power drive arm. If you review the photos in the ATSB reports, the initial failure occurred at the circumferential bolt holes releasing the disc to overspeed. From a design point of view, it is never good to have bolt holes in the area they are in because of the fact bolt holes are built in stress risers. So this was the weakest point once the disc overheated due to the oil fire.

At some point in time, seconds after the power drive arm failure, the disc, still containing the turbine blades, moved rearward, contacting the inner band leading edge of the LPT stage 1 nozzle ring. There was no IP blade to LP nozzle contact to slow the accelerated disc. At this point in time, the disc was highly accelerated, near burst and had stretched so that the "pine tree" features of the disc were enlarged, the turbine blades were now loose. The contact with the LPT nozzle created the metal splatter and then the disc burst. The turbine blades may have come out of the several disc fractured sections in two directions, radially and rearward as the disc departed the engine.

I agree with barit1, this is a classic disc burst, have seen it happen in a test cell, not a pretty sight.

[Turbine D]

barit1 & Lyman,

Here is the Trent 900 engine cross-section for your information. Also, one thing I forgot to convey, the disc burst speed I gave was for a normal operating temperatures. With the oil fire, the disc burst speed would be perhaps significantly less...

http://i1166.photobucket.com/albums/q609/DaveK72/trent900u6cu-1.jpg

TD

[Lyman]

Hi gents. I do not misunderstand your conclusions. Matter of fact, it is very difficult to disagree with them. The Problem.

The drawing is not the one I had in my other computer, which is presently in maintenance. I'd like to condense the crux of my disagreement around the Shaft/Arm/Wheel system.

I caught flack in the first thread for stating that the Wheel and Arm were made up of three parts. I was unclear. Let me start by saying that in this assembly I see three elements. The rim, and blades, the face, or disc, and the Arm, or Drive.

The first design concept I see is the "wraparound" feature of the Arm. Attached outside the bearing load, it performs a 180 to wrap the Shaft as it extends forward to capture the Disc. Is this common? I am familiar only with engines that include rotors inside the "Load frame" iow, attached directly to the shaft. As it is, the Wheel drives a load that is outside the bearing plane "The Attach" So I see potential problems with balance, and resonance.

As barit1 says, and TurbineD agrees, these rotors are of immense strength. Now that is subjective, and since failure is obvious, here, I refer to my earlier comment that due fire, the designed fail (rpm) was reduced, perhaps "substantially" as Turbine D points out.

My intention is to direct the comments (if you agree) toward the method of attachment of the Arm/Wheel, and if you are familiar with any potential pitfalls?

Because although TurbineD disagrees with my "Bell" shaped comment, I think we can see that the Arm and disc create a shape that is similar to bell, mushroom, umbrella, etc. and that this shape must resist a somewhat more complex strain profile than the Wheel/Axle tradition.

Your participation is optional, of course, but I am serious, and believe in addressing some of these concerns; at least one person will gain some knowledge, here. And tht would be me....

ad. For instance, as I say, the load is outside the bearing loadframe. Standard would be within at least two bearings, rather than attached at the end of a shaft supported only one side of the load. A corollary might be "whirl mode", where a great deal of mass and energy is "extended" past a point of support, such that the bearing is stressed in ways that are common to rapidly spinning systems, but ordinarily are suspended between two mounting points....

Please note that according to the drawing, the wheel contacts the LPT platform/stator with its blades prior to the more core oriented partition. So the false bearing would have to "wait" for the wheel to arrive post stator contact?

Isn't this IPT blades contact a design feature, to prevent OverSpeed? Scrub off the blades to prevent a drive surface for the gas path? If so, what failed, in this case?

Is the bearing mount portion of the joint connected to the race? So, can the outer race support the wheel, post separation from Arm? I would offer yes, but there would be a lot of play between the race and the inner surface/drive arm?

Note for comparison the architecture of the HP Rotor, supported on one face by the HP cap bearing, and on the other face by the shaft proper? Here, the loads are functionally within the two bearing planes, and the one sided torsional affect is snubbed?

Similarly, although the Fan is supported outside the bearing run, it has two bearing planes, which provide a 'moment arm' to capture the oddities this disc encounters with the atmosphere, and FOD? Connected as it is to the IPT terminus, and the radius of the bearing system it suggests a very robust carriage for the bulk of the a/c thrust.....

TD, barit1, what would be your opinion on the Drive Arm subject to these torsional anomalies whilst under the climb load of the gas path? Would undue fatigue weaken, and/or heat the system? Mind, the HP bearing and the IP bearing rotate opposite each other, at times with a differential of 20000 rpm.

[barit1]

First off, my expertise (such as it is) does not include rotor dynamic vibration, but I think having the plane of the IPT disc directly over the aft IP bearing (i.e. zero overhung moment) might have some advantage re whirl mode. But I have never seen this arrangement employed before.

Second, I wonder just how accurate the flowpath detail in Turbine D's cross-section is, especially in the IPT > LPT area. I could see where the inner band of the first LPT nozzle stage could contact the IPT blades at the TE root, perhaps initiating blade failure. This would seem to be in conflict with the failure sequence in the powerplant report. I think Lyman is in agreement here.

[lomapaseo]

I could see where the inner band of the first LPT nozzle stage could contact the IPT blades at the TE root, perhaps initiating blade failure. This would seem to be in conflict with the failure sequence in the powerplant report

I'm puzzled by the words (my bold) in the quote above.

Do you have a link to the section of the report that you refer?

Typically it is only in a final report which may contain an analyis where critical details are explained and supported.

My read so far is that a local (oil fire) overheat occurred sufficient to release the IPT disk from the compressor load at the drive arm.

This overheat may include only the innermost portions of the turbine disk.

Does the referenced report detail any estimates of disk body material strength from Bore to rim of the disk?.

If not then the strength of the disk may have been only marginally impacted by the oil fire.

Regardless of the answer to my question, the released disk from its drive arm is an important detail in its progression. If it was only completely released in the tangential direction (torque loss only) then it may not have permitted the free disk from moving aft into the aft nozzle vane clusters.

Whether the disk moves aft or not, it would still free wheel up in speed at a very rapid rate while remaining centered about the engine centerline. The tendancy is for it to seek restraint both upon the remaining drive arm/shaft pieces as well as its still intact blade tips against the outer case structure.

The time between the separation from its drive arm and burst would be dependant on several factors

1) the average material strength and average temperature in the compartment (local strength losses due to a localized fire would not be significant as the disk stretches and redistributes its strain)

2) The residual pressure trace across the turbine blades vs time

3) any loss of turbine blades in this stage

Rubbing friction itself against the aft nozzle vanes and between the blade tips and case would be negligible in such an event.

Likewise any false bearing between the blade roots and the aft nozzles would be negligible.

I haven't seen any factual information that suggests that blade to vane contact would be expected in the airfolis for this design.

In the end it's a F=MA over time that assess how far aft the rotor might have moved vs the speed vs time of the free wheeling disk under a decreasing gas load.

If any of the above has been convered already in a report I would be pleased to read it.

Meanwhile I am quite happy with the recommendations provided by this investigation todate (Fault analysis vs quailty control at the manufacturers)

[Lyman]

Lomapaseo,

@ TurbineD...."I assure you that the intact disc (minus the drive arm flange) is only unsupported for a few milliseconds, as the gas pressure drives it aft to a false bearing surface in the LPT inner duct. Now it is once again supported against a fairly low-friction surface, akin to the thrust bearing on your car's crankshaft against which your clutch reacts.

I think TurbineD is correct here, and from the statement, aft migration puts the Turbine's airfoils into the LPT Stator ring, where they are ejected from their slots. This eliminates the ability of the gas path to turn the IPT. The amount of aft migration is failure dependent; but if the circumferential fracture happens about the bolt flange, as he proposed, their is nothing to prevent the drift from continuing well past the Stator into the inner web of the partition.

The HP is receiving fuel in excess of the rpm ratio to flow, (via EEC), I think raw fuel may have entered the cavity to exacerbate the fire post separation, making matters worse. In any event, where do you put the fracture?

[Lyman]

@lomapaseo.....Whether the disk moves aft or not, it would still free wheel up in speed at a very rapid rate while remaining centered about the engine centerline. The tendency is for it to seek restraint both upon the remaining drive arm/shaft pieces as well as its still intact blade tips against the outer case structure.

Noting the room between the bearing box and the drive arm, I would disagree that the Turbine remains centered about its shaft, (the engine's centerline). Gas path pressure and gyroscopic forces work against this type of ad hoc stability, IMHO. So I picture the bore portion as contacting the bearing box in a random and chaotic fashion, not conducive to the Turbine's retention, and destructive of its ability to remain in the engine. This impacts the blades against the platform, and they are lost, immediately.

In any case, do you not agree, that from the drawing, the LPT Stator platform makes first contact as the IPT drifts aft?

[Lyman]

From the drawing, I note a build up of the LPT vanes platform at the area that makes contact first with IPT should it drift aftward. The portion of the IPT that makes contact with this strengthened area is the blade root circle. This in anticipation of wheel release, the design is meant to remove the airfoils in just such an emergency as this explosive burst.

As the design consideration, it demonstrates an improvement in concept, an anticipated mitigation. I suggest that it worked; as bad as this incident appears, if IPT retains its blades any longer than apparent here, the a/ c may have been lost.

[Turbine D]

Lyman,

Your quote: From the drawing, I note a build up of the LPT vanes platform at the area that makes contact first with IPT should it drift aftward. The portion of the IPT that makes contact with this strengthened area is the blade root circle. This in anticipation of wheel release, the design is meant to remove the airfoils in just such an emergency as this explosive burst.

As the design consideration, it demonstrates an improvement in concept, an anticipated mitigation. I suggest that it worked; as bad as this incident appears, if IPT retains its blades any longer than apparent here, the a/ c may have been lost.

No, No, No, that is what you don't want to have happen. What you want to have happen is the turbine blades to stay with the disc which is holding them so that if the disc becomes liberated and if and when it moves back, those turbine blades clash with the turbine nozzle airfoils behind slowing the disc acceleration before it gets to a burst situation. What would then happen would be a bunch of ground up airfoil pieces exiting through the LPT and out the exhaust pipe, but the disc would slow down and remain intact. That is what happened on several older model Trent engines where blade to nozzle contacted prevented disc bursts.

In the case of the Trent 900, when the disc became free, overspeed initiated and when it move back, the contact with the stage 1 LPT nozzle occurred at the disc rim rubbing out the turbine blade retainers thereby creating the potential for the blades to come out and making no airfoil to airfoil contact slowing the disc speed. Remember, there was little damage to the LPT other than the stage 1 LPT nozzle with most of the remnants, disc sections included, exiting radially, not good. I will look again at the photos in the ATSB reports to be sure of this scenario as I am doing it at the moment from recall. In the meantime, look at the GP7200 engine cutaway below.

You will note that if the stage 2 HPT disc (similar position to the IPT disc) became liberated for one reason or another, if it would move back, the turbine blades would clash with the stage 1 LPT nozzle slowing the disc speed. It is an important design feature to inhibit runaway disc speed.

lomapaseo,

All I can say about the intensity of the fire from the burning oil is what the ATSB said in their Interim-factual report:

The investigation has found that the intermediate pressure (IP) turbine disc failed as a result of an overspeed condition, liberating sections of the IP turbine disc that then penetrated the engine case and wing structure. The disc failure was initiated by a manufacturing defect in an oil feed pipe that resulted in a wall thickness reduction in an area that is machined to receive a coarse filter. That section of the oil feed pipe sustained a fatigue crack during engine operations that lead to an internal engine oil fire that weakened the IP turbine disc. In turn, a circumferential fracture was induced around the disc, allowing it to separate from the IP turbine shaft. The unrestrained disc accelerated to critical burst speed. This lead to the No 2 engine failure and subsequent significant penetration damage to the airframe structure and systems.
I do think there is some merit in what you suggest, the disc stayed centered for a short period of time during the acceleration.






http://i1166.photobucket.com/albums/q609/DaveK72/mc03_lg.png

[Lyman]

I take it then that the airfoils are to be sacrificial? I do not see how the IPT blades can clash with the LPT vanes without transiting the Stator "Platform".

They cannot get there from there. They have to slice through 10 centimeters of platform to access the Vanes. Now that may slow the Wheel, but the blades are lost anyway. If it is as you say, why provide an impediment to instantaneous clash post separation at the ARM? It is not sensible.

I was sure I asked more questions, and I'll stand by the scrub foils for now. May I choose one question to ask? How about the open space between the Bearing box and the bore of the IPT? Sufficient to restrain the IPT and offer a bearing for overspeed? Without allowing aft drift, or Disc eccentrics, wobble?

I prefer the TRENT7 pic to the more pedestrian T9drawing......Are they exactly similar? I see that they are not, the foils are pitched the same way. No contra.

[Lyman]

TD......"You will note that if the stage 2 HPT disc (similar position to the IPT disc) became liberated for one reason or another, if it would move back, the turbine blades would clash with the stage 1 LPT nozzle slowing the disc speed. It is an important design feature to inhibit runaway disc speed."

Come again? I just said that, re: TRENT 900? How does HPT climb through the IPT to get at LPTNozzle? Blade clash is a bad thing for the 9, but ok for the 7?

[Turbine D]

Lyman,
Your quote: I prefer the TRENT7 pic to the more pedestrian T9drawing

The (GE/Pratt) Engine Alliance GP7200 is a 2 spool engine verses the Trent 900 that is a 3 spool engine. By showing you a cutaway of the GP7200 engine, I wanted you to note only this:

If the stage 2 HPT blade rotor, for whatever reason, moves rearward, disconnected from the shaft, the turbine blades would clash with the stage 1 LPT nozzle airfoils, slowing the disc rotational speed down below that of burst overspeed.

In the Trent 900, if the IP turbine rotor, for whatever reason, moves rearward, disconnected from the shaft, the turbine blades cannot clash with the stage 1 LPT nozzle airfoils to slow the disc rotational speed down below that of burst overspeed.

The difference between the two engines lies in each of their basic designs. The Trent 900 engine is also different from previous (older) Trent designs where blade to nozzle clashing is possible and did occur in several failure instances. So, the Trent 900 is unique in its apparent design and positional relationship between the IP turbine rotor and the LPT stage 1 stator (nozzle). I am not going to speculate as to why the Trent 900 design was developed the way it is.

I don't know how to make this any clearer to you, take your time to understand what is presented, I know it is somewhat complex...

[Lyman]

So let me ask you then re: your response. Does the GP have an IPT turbine that is affixed with the same architecture as the T9? Because if it is fit on to the shaft via keyway or splines, the overspeed would happen , should the key(s) shear, or the splines grind smooth. It is the false bearing that interests me.

So one question then. Can you show me the false bearing locus? Because any aft movement at all of the IPT in the TRENT puts the aerofoil ring into the LPT Stator. Isn't that accomplishing the same thing as the GE in wheel loss? Design aside, I see no room for false bearing to establish, without IPT/LP1Nozzle conflict. At 500 pounds, the IPT would take out anything in its way, and I do not see how you propose the Bearing box to contain it to capture gas path, and resultant spin up? The relative bore/diameter of this 'new' bearing/system does not look like it is up to keeping the Wheel from axial drift, and/or blade clash with LPT Stator.

I do not see the LPT vanes at all in the GE/PRATT.

[Turbine D]

Lyman

Your quote: Does the GP have an IPT turbine that is affixed with the same architecture as the T9?

The GP7200 engine does not have an IPT rotor, it is a two spool engine and the HPT consists of two rotors, Stage 1 and Stage 2.

Your quote: I do not see the LPT vanes at all in the GE/PRATT.

Perhaps this view of the GP7200 will enable you to see the Stage 1 LPT nozzle in relationship to the Stage 2 HPT rotor.

http://i1166.photobucket.com/albums/q609/DaveK72/gp7000_cutaway_high.jpg

Your quote: Because any aft movement at all of the IPT in the TRENT puts the aerofoil ring into the LPT Stator. Isn't that accomplishing the same thing as the GE in wheel loss?

I don't think it does on the Trent because of the angular lean of the Stage 1 LPT vane, refer back to the Trent cross section. The impingement between the two on the Trent is close to the blade root and disc pine tree holding the blades and the inner band extension of the Stage 1 LPT nozzle ring. If you look at the recovered parts photographed in the ATSB report, you can note 2 items of interest. On the recovered LPT vane segment, the inner band is gone. Also, the turbine blade retainers on the recovered portion of the IPT disc are all missing. So you have relatively one smooth surface contacting another relatively smooth surface. Beyond, these observations, nothing more can be said with any certainty. Even with all the recovered parts, lab analysis, etc., plus the assistance of the engine designer and builder, it is difficult to reconstruct the minuscule details of exactly what happened in the few seconds following the release of the IPT rotor disc and blades to the degree you are attempting to without the complete data the ATSB possesses and the knowledge RR has on this engine.

[Lyman]

TurbineD

As always, thanks for your patience and expertise. A quote from you....

You will note that if the stage 2 HPT disc (similar position to the IPT disc) became liberated for one reason or another, if it would move back, the turbine blades would clash with the stage 1 LPT nozzle slowing the disc speed. It is an important design feature to inhibit runaway disc speed.

In either engine, the Power Turbine, (IPT in the TRENT, and HPT2 in G/P) send the gas path into the (stationery) nozzle of the engine's LP (turbine) cavity. In the G/P, the vanes are elongated and occupy the plane directly behind the blades of the Power Wheel. The Trent's Vanes appear shorter in length, and are arranged at some distance aft of the preceding rim of the STATOR. This means, as you say, that blade clash will not occur instantly, and the effacement in aft drift occurs with two smooth surfaces, rather than Blade/Blade.

I am speculating as to design. To me, it (TRENT9) represents a sequential approach to Disc runaway. The Wheel is slowed, and borne temporarily at Blade roots/Stator platform, (your "On the recovered LPT vane segment, the inner band is gone. Also, the turbine blade retainers on the recovered portion of the IPT disc are all missing.") So you have relatively one smooth surface contacting another relatively smooth surface. This wipes the retainers, and the blades loosen in the IPT. As the blades begin to depart the wheel, the IPT captures less of the power of the gas path, and the blades shred, to fill the cavity with shrapnel. This shrapnel, I see as a benefit to further loss of blades and resultant loss of rpm. As the IPT travels further back, the Platform degrades into more robust areas of the Platform, and eventually the Blades/Vanes efface.

The IPT, off arm, does not have a solid support at the bearing box, though it does have concentric structures post fracture. This allows an eccentric braking action, though the vibration and noise must be extreme.

At the last, the IPT foils (if any are left) scrub the Vanes of the LPT nozzle, removing the last of them.

As you point out above, blade/blade is the G/P approach to arrestment, RR similar, but with a primary contact at blade roots, Stator platform. Again, I believe that the desire is to slow the wheel, but I would add that equally important is to defeat the gas path mechanically, a fuel cut is not possible in this time sequence.

So I can only say that the approach is different in the 900, but to me represents a step ahead of that taken by GE/PRATT.

I do not discount the overspeed, but I note that you agree the design limit for separation of the wheel into three parts may have happened at lower than maximum rpm for integrity. Yes?

Thanks again

[JuergenP]

Turbine D is your man here. He should be working for the ATSB.:ok:

Lets not forget that this was a T972 on very heavy work cycles esp out of LAX ro Oz. RR made a severe error in an oil pipe bore. Qantas are persuing them in court.

This engine was not a T970 or a T1000.

Turbine D is one of the very few people who had the quals and tactile experience to assess this engine failure.

And as for No. 1 engine running on a for a full hour .. what can you say..God was with them.

[RichPa]

Sorry for asking this, it would be impossible for me to read this huge thread, could someone explain to me how it was possible that the engine can not be stopped by any method after landing? Is this an A380 issue or a general flaw regarding all modern FADEC jet engines?

[DozyWannabe]

It's specific to neither A380 nor FADEC. If the control connection to the engine is damaged or severed, then it cannot be shut down. For an older example, the Pan Am 747 at Tenerife in 1977 had its engines running even as it was consumed by fire. This was because the impact from the KLM 747 had ripped out all the engine control cables, which in the 747 run through the ceiling of the lower cabin.

[RichPa]

Thank you very much for your answer. I guess it is designed that it is better to run in case of malfunction in the air instead of inadvertently shutting off, right?

But even using the fire switch doesn't work, does this seem ok to you? What do you think?

[DozyWannabe]

It's not really a case of being OK or not, it's just a basic fact that if the control connection is broken, it's not going to work. Thankfully such occurrences are very rare.

[RichPa]

I just can't think what if the engine wasn't at idle, the outcome of not being able to shut it down it had been really serious.

[Turbine D]

Dozy,

Don't forget about the A-340 testing incident at Airbus that hit the wall on November 15, 2007...

From the BEA Report:

Engine #3 and #4 kept running after impact and did not stop immediately. It was not possible to shut them down, neither by activating the fire extinguisher handles nor by positioning the thrust levers on OFF. Water and foam spray on engine #4 managed to extinguish it at 18:48.

Due to the proximity of the wall this was not was not possible with engine #3 in a similar manner to engine #4. It shut down by itself only on November 16 at 01:25 after it had consumed all the fuel from its collector tank.
Again the electrical connections from the engines to the cockpit were severed.
http://i1166.photobucket.com/albums/q609/DaveK72/340den10_zpsac843f06.jpg

[RichPa]

:eek:Were they jammed above idle?

[barit1]

At the risk of being redundant (again), let me point out that R-R has suffered a few turbine disc disconnects - with different engine models, different containment philosophies, and quite different results.

I give you QF74, 744, RB211 on 30 Aug 2010 (SFO local date): Qantas QF74 Uncontained Engine Failure - Video & Pics (http://www.flight.org/blog/2010/09/01/qantas-qf74-uncontained-engine-failure-video-pics/)
IPT came disconnected from its shaft and drifted aft due to pneumatic forces in the engine. In this case, the IPT blades DID clash (i.e. first made contact) with LPT stator vanes, thus very rapidly destroying the driving torque to the loose IPT disc. Blade shrapnel penetrated the case and cowl, but the pieces were relatively small so the damage to the airframe was limited.

Contrast this with the QF32, A380, 04 Nov 2010 SIN: T972 suffers IPT disc rupture after shaft disconnect. No rotor/stator airfoil clash, instead the disc became axially restrained against relatively hard/smooth/low friction internal surfaces. Disc continued to accelerate, driven by relatively intact airfoils, until burst speed was reached.

Which, I ask you, was the more successful containment?

[lomapaseo]

Which, I ask you, was the more successful containment?

The requirement and design intent for containment is not a 100% requirement which of course is impossible to acheive so it's not even attempted.

Instead the regulations look at it as similar to many other requirements including birds, ice etc. The regulations set forth a minimun level that must be demonstrated by test and analysis.

For engine containment the demonstration requirement is for the more likely failure of a blade and its consequences at maximum running speed. Given that in the QF 32 event a disk separation occured t would have been impractical for any engine design currently existing to have contained the debris by verifieable design.

Instead the burden falls to the design intent to minimize the failure condition that caused the non-containment using best industry practices. This does include but is not limited to the presumption that some designs will permit the blades to be mangled in order to save the disk.

Indeed there was a lesson learned in all this for all manufacturers not just RR

[barit1]

Indeed there was a lesson learned in all this for all manufacturers not just RR
I submit that for some, this was a painful re-learning of an old lesson.

Turboshaft/turboprop designers learned long ago they must design for the loss-of-load case - shaft or gear failure, loss of a prop, etc. Turbine overspeed can occur very very rapidly in this case, and active overspeed protective systems are commonly employed to protect the aircraft.

[Joetom]

Containment can be achieved, but too heavy(£/fuel) at the moment.

I thought some APU's in the tail cone have it but only to avoid the tail/tail control devices being damaged by items/parts leaving the engine, however to save weight, items/parts can exit it other directions, I never walk below an operating APU.

[Turbine D]

I just can't think what if the engine wasn't at idle, the outcome of not being able to shut it down it had been really serious.
The engine on the QF32 was not at idle, it ran at the thrust setting at the time when the disc failure on the adjacent engine occurred during climb out. As I recall, the crew had to deal with this fact in calculating the landing distance required and maneuvering the aircraft to line up on the approach to the runway. They did not know the engine wouldn't shut down until the very end of the rollout when they attempted to shut it down.

[barit1]

Let us be clear about this:

DISC failure is unlikely to ever be contained because of the size/mass/velocity of the disc fragments. The mitigation for this is to make a disc failure very unlikely. The sacrifice of turbine blades by interference with stator parts is a small price to pay in protecting the aircraft, even if it results in a lesser-energy uncontained failure.

On the other hand, BLADE failure is generally containable, or at worse, a low-energy case penetration.

[Turbine D]

RichPa,
Were they jammed above idle?
From the BEA Final Report (I eliminated the sections pertaining to brake details):
Between 15:58:10 and 15:59:03 the thrust is increased gradually from idle to a steady value of 1.25 EPR. This engine thrust setting corresponds to a position of the thrust levers between MCT (Max Continuous Thrust) and MTO (Max Take Off Thrust).

At 16:02:06 the person in the right seat starts talking but is interrupted at 16:02:08 by the person in the left seat who announces :
“Euh ... cabin is ... aircraft is moving forward”

The first significant LONGITUDINAL ACCELERATION parameter values showing a forward acceleration of the aircraft are observed around 16:02:07. The recorded ground speed starts to increase at 16:02:09 (3)

Note (3): Ground Speed values are recorded in increments of 1 kt.

Between 16:02:08 and 16:02:13 the ground speed increases from 0 to 4 kt.

At 16:02:11 the person on the left seat again says :
“Aircraft is moving forward”

An action on the brake pedals is recorded from around 16:02:11

The parking brake is deactivated around 16:02:13
The person on the right seat announces :
“Parking brake off”

From the moment the park brake is released:
• the brake pedals are briefly released on two occasions
• the recorded ground speed increases rapidly from 4 to 31 kt in seven seconds

The angle of the nose gear reaches 77 degrees right at 16:02:19 and remains at that value until the end of the recording. From 16:02:18 we can hear on the CVR severe vibration noises followed by impact noises.

The thrust levers did not move until 16:02:20 when they are retarded to the IDLE detent. The EPR values of the 4 engines start to decrease immediately afterward.

The longitudinal acceleration becomes significantly positive, indicating an aircraft deceleration, around 16:02:20.5

FDR recording ends between 16:02:21 and 16:02:22
I would assume the engines that couldn't be shutdown were at idle or close to idle.

[Turbine D]

barit1,
The sacrifice of turbine blades by interference with stator parts is a small price to pay in protecting the aircraft, even if it results in a lesser-energy uncontained failure.
I absolutely agree with your statement. It is a best design practice. You may not be able to prevent a disk that fractures due to a defect, but you can prevent a run away disk reaching a burst speed condition by the design and interactions of the surrounding airfoils.

[kennr]

The ATSB report is now out... see Investigation: AO-2010-089 - In-flight uncontained engine failure Airbus A380-842, VH-OQA, overhead Batam Island, Indonesia, 4 November 2010 (http://www.atsb.gov.au/publications/investigation_reports/2010/aair/ao-2010-089.aspx)

[IFixPlanes]

The final report (http://bit.ly/19W4taV) is online.

[40KTSOFFOG]

Report into the Qantas A380 Uncontained Engine Failure has now been published!


http://www.atsb.gov.au/media/4148371/ao-2010-089_final.pdf

[IFixPlanes]

To lazy to search for the original thread?
http://www.pprune.org/tech-log/437978-qantas-a380-uncontained-failure-post7911846.html#post7911846

[deptrai]

after a cursory skim through I was a bit surprised not to see recommendations regarding ECAM (irrelevant or even conflicting items), but at a second glance it seems some of this (trim tank availability) may already have been taken care of by Airbus. Seeing the extensive damage documented in detail still makes me shudder, yet simultaneously I'm thinking, chapeau to modern engineering (Airbus in this particular case, more than RR Trent):

The effect on the aircraft’s controllability in those configurations was rated as ‘minor’ and

Despite significant system and structural damage following the uncontained engine failure, the simulation identified that the aircraft had sufficient redundancy to continue safe operation

[lomapaseo]

One of the most thorough reports I have seen. :ok:

I wonder if the other manufacturers will learn from it. It highlighted problem areas that certainly are not unique to RR or Airbus.

Very few investigating agencies in the world would have the staff or level of expertise to produce such a report. I only hope that such agencies will assist their brothers when the need arises.

[pattern_is_full]

Whoof! Took me three times longer to read the report than it did for the crew to handle all those ECAM items.

All that from a ~1mm machining error.

[barit1]

All that from a ~1mm machining error.

That was only the first domino to fall.

In the basic architecture of the turbine section, the IPT system could not tolerate a shaft separation; It was virtually guaranteed to overspeed until the disc burst. That is a basic design issue; the manufacturing fault in the oil tube was merely the straw that broke the camel's back.

[lomapaseo]

That was only the first domino to fall.

In the basic architecture of the turbine section, the IPT system could not tolerate a shaft separation; It was virtually guaranteed to overspeed until the disc burst. That is a basic design issue; the manufacturing fault in the oil tube was merely the straw that broke the camel's back.

Of course they have addressed that little detail by changing the architect of the FADEC

I hope their FMEA analysis shows that good engines will not be shutdown erroneously with this doomsday code

[cybercy]

Re Qantas, Rolls Royce, Airbus
Who knew prior to 4 Nov 2010
that there was a high risk in the occurance of a QF32 failure and where there was no informed consent in advance of departure?

Cybercy

[barit1]

In fact there were two warning signals earlier in 2010:

I give you QF74, 744, RB211 on 30 Aug 2010 (SFO local date): Qantas QF74 Uncontained Engine Failure - Video & Pics
IPT came disconnected from its shaft and drifted aft due to pneumatic forces in the engine. In this case, the IPT blades DID clash (i.e. first made contact) with LPT stator vanes, thus very rapidly destroying the driving torque to the loose IPT disc. Blade shrapnel penetrated the case and cowl, but the pieces were relatively small so the damage to the airframe was limited.

The above happened within a few weeks of a RR test bench failure of another Trent (787 version). Little detail is publicly available, but I believe I heard someone mention IPT.

Contrast this with the QF32, A380, 04 Nov 2010 SIN: T972 suffers IPT disc rupture after shaft disconnect. No rotor/stator airfoil clash, instead the disc became axially restrained against relatively hard/smooth/low friction internal surfaces. Disc continued to accelerate, driven by relatively intact airfoils, until burst speed was reached.

[lomapaseo]

In fact there were two warning signals earlier in 2010:

Warning signals consist of two parts...... cause and effect.

I doubt that anyone foresaw that the combinations that occurred in QF32 were likely.

Afterwards it's easy to look at all combinations ever having occurred in the total data base of the industry and then say, not surprised given etc. etc.

[barit1]

I'm not saying they were in any way identical - only that IP shaft separations occurred and these should have sparked a "what if..." in some engineer's mind. QF32 should not have been a complete surprise. :=