Boeing's final word/RR-Trents

[CAPTDOUG]

SUBJECT: 777-200/Trent 895 N862DA Thrust Rollback During Cruise - 26
November 2008


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UPDATE 1 UPDATE 1 UPDATE 1 UPDATE 1
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Reference a) provides Boeing's previous fleet communication of a 777-200
with Trent 895 engines that experienced an uncommanded thrust rollback on
one engine while in level flight cruise at FL 390. The thrust rolled back
to a level above idle on that engine, approximately 40 minutes after a VNAV
step climb. The flight crew performed the Engine Response non-normal
checklist, which restored full capability to the engine for the remainder of
the flight. The other engine operated normally throughout the flight.

Based on the FDR data and the characteristics of the roll-back, it is
suspected that accumulation of water ice in the fuel path of the Fuel Oil
Heat Exchanger is the cause of the subject incident. Although the
circumstances are slightly different, the subject incident is believed to
have been caused by similar factors as those experienced in the 777-200ER
G-YMMM accident at London, Heathrow airport on 17 January 2008 as described
by Reference b).

Investigation Status
It should be emphasized that the investigations into both events are not yet
complete, with the G-YMMM accident under an open investigation by the UK
AAIB and the subject roll-back incident under an open investigation by the
US NTSB. Boeing, Rolls-Royce, the operators and other organizations are
supporting both investigations.

Recommended Operator Action
The circumstances of the subject thrust roll-back incident have led Boeing
to review the cold fuel operations procedures released by Reference c).
Based on this review, it is believed to be prudent to revise the interim
mitigating procedures to account for what was learned in the subject
roll-back incident. Changes to the interim procedures include:

Reduce the window at top of descent from 3 to 2 hours;
Assure the crossfeed valves are closed;
Assure minimum idle thrust for 30 seconds during initial descent, and;
Clarify the Condition statement in Engine Response Non-Normal Checklist
(NNC).

Reference d) provides a list of publications from Boeing that give the full
definition of the revised interim mitigating procedures. The FAA and EASA
are expected to release regulatory action to mandate use of the revised
procedures. These procedures are interim measures that will remain in place
until a permanent solution can be defined, tested, certified, and deployed
to the fleet.

Other Airframe/Engine Combinations
These interim mitigation procedures only apply to 777s powered by
Rolls-Royce Trent 800 engines and do not apply to other airframe/engine
combinations. Based on our knowledge of the system configurations, scenario
studies, and laboratory test results, we do not believe that immediate
action is necessary or warranted for 777s powered by other engine types or
non-777 airframes regardless of engine type.

Studies of the applicability of the thrust roll back circumstances to other
engine types and airframes are in work and will continue. Boeing will
notify operators of the results of those studies as appropriate.


Tom Dodt
Chief Engineer - Air Safety Investigation
The Boeing Company
Download this as a file

[EASY 69]

'The newest 777s built by Boeing, the best-selling 777-300ER and the ultra-long-range 777-200LR, are only powered with GE engines.'

I wonder why that is then? Is there an inherent issue with the trent? Perhaps more experienced posters would care to answer.

Thanks

[Cyrano]

I wonder why that is then? Is there an inherent issue with the trent? Perhaps more experienced posters would care to answer.

Yes, absolutely, there's an inherent issue with the Trent... (drum roll)...but sorry to disappoint you, the issue is simply that the most powerful Trent version is not powerful enough for the 777-300ER/-200LR. As a couple of minutes on Wikipedia reading about the longer range 777 models (http://en.wikipedia.org/wiki/Boeing_777#Longer_range_models) and the Trent (http://en.wikipedia.org/wiki/Rolls-Royce_Trent) would tell you, the -300ER/-200LR use a 115,000lb thrust version of the GE90, whereas the most powerful available Trent is "only" 95,000lb.

[Dysag]

GE got exclusivity on the 777 ER/LR in exchange for them developing the 115k lb engine Boeing needed.

A purely commercial deal, nothing to do with technical features of the Trent.

[Lord Bracken]

"In 1998 Boeing proposed new longer range variants of the 777X; taking advantage of the Trent 800's growth capability, Rolls-Royce designed and built an improved engine designated Trent 8104 which was later scaled upwards to the even larger 8115. This development was the first engine to break through 100,000 lbf (440 kN) thrust and subsequently the the first to reach 110,000 lbf (490 kN). However, Boeing required that the participating engine developer assume a risk-sharing role on the overall 777X project. Rolls-Royce was unwilling to do so, and in July 1999 Boeing announced that it had chosen the development of the GE90, the GE90-110B and GE90-115B to be the sole engines on the long-range 777s. This resulted in the 8104 becoming just a demonstrator programme, despite setting further industry firsts for thrust levels achieved and the first to demonstrate the use of a fully swept wide chord fan."

[airfoilmod]

The point of the posts related to engine choice. Time marches on, things happen, technology evolves. Is a commercial decision somehow uhm... disrepectful? To be specific, the Trent located its HE in a different place and went with no recirc. It also has an extra spool. I'm a "fan" of RR;

I think no defence needed.

AF

[PAXboy]

CAPTDOUG, the first thread you started about this incident is still open and available. Don't get greedy!
http://www.pprune.org/rumours-news/360548-dal-rollback-update-trent895.html

[Duck Rogers]

Quite.

Threads merged.

[WindSheer]

Lets be honest, all this is just part of the evolution of airplanes.
As long as this problem is controlled by the knowledge that has been gained until a rectification is made, then we are all happy.

But, on the other hand, if another frame comes down there will be hell breaking loose!! :uhoh:

Although the triple seven would never be grounded if it did happen again, because its american!!:mad:

[EASY 69]

Cyrano/Dysag - thanks for pointing that out, however my point is were RR unable to provide a higher thrust engine to boeing, or did they not want to because they new they already had issues. As Lord b states they had developed upto 110k but then pulled out, doesn't sound very commercial to me. I would imagine a lot of RR donk operators who were looking at the 777 LR variants would have been uhappy with that decision.

[boeing boeing.. gone]

EASY 69

from my undertsanding Boeing wanted to enter into a risk sharing agreement with RR on the larger variants. RR did want to do that so pulled out. Essentially if the 777 larger variant failed commercially RR would have lost out badly

[Re-Heat]

I would imagine a lot of RR donk operators who were looking at the 777 LR variants would have been uhappy with that decision.
Apart from Emirates who were initially unhappy with RR on the base 777s, and were very happy to see GE as suppliers to 777 growth varients.

[EASY 69]

'Essentially if the 777 larger variant failed commercially RR would have lost out badly.' - conversley if the 777 larger variant suceeded commercially RR would have done very well, or would they. Seems to me that they knew something was adrift with the engine and pulled out of further development. As it stands,two rollbacks, as of yet not fully explained by the investigators, on an aircraft that it WAS designed for seems a little bit of a concern.

[boeing boeing.. gone]

EASY

Do you honestly think RR would not have fixed a minor problem such as plate heat exchange unit if they knew it was faulty or they thought the engine was inherentley flawed!!! come on!!!! Saudi airlines had to change a number of their GE engines in 02 on the 777 because of a failure of some bearings, by your own summary does that make the GE unsafe?? UTTER DRIBBLE. the trent has been flying for years and up until recently was very succesful and reliable.. (and for me 2 incidents don't make a bad engine) I wouldn't hesitate stepping onto a RR powered 777... Personally i would rather fly on a plane with power from RR than GE or PW....

waits for abuse.....:mad:

[EASY 69]

boeing boeing.. gone no, not at all, but there again they didn't and a minor problem becomes a big issue. Me personally, I love them all.

[sky9]

Easy 69, you seem to be very ignorant of the facts while keen to voice an opinion. It might be better (for your own credibility) to read more and post less.

[EASY 69]

What facts would those be then sky 9?

I believe having spent 35 plus years in aviation that I have at least some knowledge,and like most people I like to voice an opinion on something that I have an interest in or a concern about.

[airfoilmod]

Last year all 777's (UAL) had to deplane their pax and deadhead to MOC to check a firing mechanism on #5 fire bottle. This item was actually deferable, but the line recalled anyway.

Sometimes methinks the messenger takes flack when partisans are frustrated at events.

I don't see this as any thing other than the unfolding of commerce, and an opportunity to progress.

AF

[bvcu]

If we're talking rollbacks , there was a software issue that meant an extended period of TOGA takeoffs on the GE powered ER/LR until the problem was fixed . Not the same as a suspected icing issue but still just as scary . Think if you look at all the types/engines at some time in their development there are issues which eventually get resolved , just more gets in the public domain now!!

[boeing boeing.. gone]

bvcu

you have said exactly what i was trying to, but far more elequently:ok:

at the end of the day all the engines types that are hooked on to the 777 airframe must be good otherwise they wouldn't be there!!!:cool:

[Torquelink]

Boeing was pressured by, among others, Singapore Airlines to offer the Trent on the 773ER and 772LR but the exclusivity deal put to them by GE was unmatchable by RR even though they were already running a Trent at above 100k/lb. The ability to develop a 115k/lb engine was never the issue. But what goes around comes around and RR now have a de facto exclusivity on the A350XWB, although they never asked for it, because GE won't / can't compete with the 773ER / 772LR by offering an engine on this type. The A350XWB has now outsold the 773ER and 772LR so RR must be smiling in quiet satisfaction. And sales to date of the GEnEX exclusive 747-8 probably means they are relaxed about that decision too. From their point of view, exclusivity isn't always what it's cracked up to be - e.g. A340-500/600.

[lomapaseo]

exclusivity isn't always what it's cracked up to be

resources resources resources dictate what you gamble on.

It isn't all the profit per model, but the development resources (labor and capital) that are limited to how many models you can actually develop per unit time.

The challenge gets easier when you have larger (money and labor) and fewer manufacturers competing.

[armchairpilot94116]

And certain airlines are forced to change their engine habits. CX with GE90 instead of their usual RR fare. And Ci with RR on their A350 order instead of their usual American engines.

[gone till november]

BBG

Personally i would rather fly on a plane with power from RR than GE or PW..

Just come back on a BA777 with GE and must admit that i was slightly edgy about it impressive looking as it was.

All the BA engineers i've spoken too prefer the Trent and i would rather travel on one too.

Didn't the GE when performing the blade off tests fail every time.....so they blew it half way up the blade and were given dispensation by the FAA for it.:oh:

Easy 69

Just an quickie....doing what for 35 years in aviation. Nothing suspisious in the question just curiosity.

[lomapaseo]

Didn't the GE when performing the blade off tests fail every time.....so they blew it half way up the blade and were given dispensation by the FAA for it

No:=

The GE met the regulations and is safe. BTW how many fan blade failures have they had that causes your concern?

and How many have RR had?

Without factual data you only have personal speculation about flight safety between engines.

[gone till november]

lomapaseo

The fact that the GE90 has not had a fan blade off yet or that it passed the test does not detract from the fact (to which i stand to be corrected) that the original blade off tests, it failed. GE was given a special dispensation to carry out a blade off test "not at the root". Im pretty sure it was documented in FI as i remember thinking at the time "that surely this cant be right" or fair.

Without factual data you only have personal speculation about flight safety between engines

ALL the BA engineers (that ive spoken to) that have worked on both engines (a position that BA is almost unique in terms of like for like power outputs) prefer the Trent. At the end of the day you have to trust their judgement and its their comments and opinions that I base my "factual data" on.

Im not saying that the GE90 is unsafe or unreliable but i know which engine i prefer to see attached to the wing. Maybe its for the above mentioned "data" but after a Tanquerray and tonic or two i start to not give a damm as i know that no airline is dumb enough to use "bad" engines.

But as the Rolls Royce advert about 25 years ago went (to the sight of an RB211 with a prominent 'RR', on a wing, seen through a passenger window) said. "Re-assuring, Isn't it". Very potent ad if you ask me. And yes i do like to see the double R on my engines.

Safe flying old bean

[bvcu]

Think you need to put the comments RE BA engineers preferences into context . This is comparing the GE 90 - 94B the Trent 800 which i fully agree with . The GE had a difficult entry to service with BA , and they then got the Trent when it had been in service a few years as it also had some problems . The most common GE at present is the 115 which powers the 777-300ER /200LR . Totally different from the earlier engine and although there are a few issues its a very reliable engine , and from a line engineers point of view , doesnt use oil and very rarely open the cowls !! Unlike the 94b !!

[CAAAD]

Sorry, lomapaseo, but the GE90 did not meet the FAR33 blade off regulation. It enjoyed the use of a Special Condition to allow separation away from the top root seration.
No other engine enjoyed this alleviation.

[lomapaseo]

CAAD

Sorry, lomapaseo, but the GE90 did not meet the FAR33 blade off regulation. It enjoyed the use of a Special Condition to allow separation away from the top root seration.
No other engine enjoyed this alleviation.

Yes I am aware of what it demonstrated. Your words are slighty more correct.

Tis true that it was certified by testing under a Special Condition of equivalency under part 33

In the end it had to show that it could be safely shut down after the release of the highest energy blade (typically but not necessarily a fan blade) released at its inner-most retention. But like an integral bladed rotor (blisk) the argument is what is the inner-most retention. GE argued that the typical disk-blade root area was to be controlled to the same standards as the disk (prime reliable) thus the inner-most portion of the blade that was exposed to similar hazards as RR & PW blades was the root airfoil.

So at least we may agree that after their redesign following their first test they have now demonstrated an equivalent level of safety?

[EASY 69]

gone till november - half of it listening to @rseholes, the other half ignoring them.

[gone till november]

Easy 69

half of it listening to @rseholes, the other half ignoring them

Hmmm....so you started as ATC and then became a manager:E

bvcu

Think you need to put the comments RE BA engineers preferences into context

I thought i did. I did say of similar power output. If i remember correctly when they introduced the GE powered 777's they used them on the LHR - CDG route due to birth pains with the new engine.

lomapaseo

From your last reply it seems that you are either an engineer or just have a deep knowledge of the GE90

But either way your post sounds like its certification was a compromise of design and testing.

following their first test they have now demonstrated an equivalent level of safety?

That in my mind is not an equal or superior level of safety.:suspect:

[lomapaseo]

gone til november


it's not yet november aren't you gone yet? :E


That in my mind is not an equal or superior level of safety

Nobody is superior as yet. Check back after the fleet is retired.

Design and certification are promises backed up by certified equality compared to the regulation standard.

[exeng]

If i remember correctly when they introduced the GE powered 777's they used them on the LHR - CDG route due to birth pains with the new engine.


Not correct I'm afraid. The CDG route was planned from the beginning to speed up Pilot training.


Regards
Exeng

[gone till november]

Not correct I'm afraid. The CDG route was planned from the beginning to speed up Pilot training.

Sorry was mis informed at the time.:ouch:

I take it back.

Still prefer to see the Trent hanging off the wing.

[JW411]

I prefer to see the Trent hanging on the wing.

[gone till november]

JW411

How right you are. :O

Lomapaseo

I thought i'd come back early.;)

Yes neither has made a huge leap infront of the other in terms of reliability but you also have to ask why did BA change back to RR when they ordered new 777's. There must have been a good reason why they would go through the expense of changing engine on the same type.

Must say though the GE90 is one quiet engine when it flies over my house.

[exeng]

I was given to understand that the original order for GE powered 777's was tied in with GE buying the BA engine overhaul facility at Treforest in South Wales.

Once all that was complete BA reverted to RR (which is probably what they wanted all along)


Regards
Exeng

[gone till november]

Exeng

That caused a big stir when they bought GE and though it caused a furore it was strenuosly denied that it had anything to do with Treforest.:confused:

But why would BA go through the whole expensive process of introducing a new engine onto an established fleet. There's more to it than meets the eye.:suspect:

[speed freek]

If we're talking rollbacks , there was a software issue that meant an extended period of TOGA takeoffs on the GE powered ER/LR until the problem was fixed

Quite right.....but how quickly people forget!! :}

And to a previous poster:

Why would Emirates be unhappy with the Trent? Until the arrival of the A380/new 777s and the departure of the classic 'busses, it was the powerplant across the fleet.

Rumour has it the GP7200 isn't what it was promised to be. Should have gone for the Trent 900......but that's another story! :E

[boeing boeing.. gone]

speed freak,

can you elloborate on the gp7200 rumour??

[Torquelink]

Totally different from the earlier engine and although there are a few issues its a very reliable engine and also ahead of guarantees on sfc as well. The 115 is doing a GE an awful lot of good - under promising and over delivering on fuel burn rather than the other way round. RR build great engines too but haven't always met fuel burn expectations - even if managing to meet specific guarantees. The 115 is showing former RR core clients such as SQ and CX that there are seriously competitive alternatives. The next test will be the GenEx vs Trent 1000 where, rumours have it, both have yet to meet sfc targets but the GE is closer than the RR.

[lomapaseo]

The next test will be the GenEx vs Trent 1000 where, rumours have it, both have yet to meet sfc targets but the GE is closer than the RR.

How much of this is the engine core and how much the aircraft nacelle? or is all this undressed early test cell stuff?

[Torquelink]

Iomapaseo,

To be honest I don't really know - just picked up snippets from friends in Seattle that following air tests on their respective 747 testbeds the GE engine is 1 - 2% off and the Trent 3 -4% off. which would, I guess, suggest that they are complete fully-dressed propulsion package results. Having said that, RR don't seem unduly worried saying they'll meet guarantees by first delivery (but see my earlier posting re GE beating their guarantees). Would be good if someone from RR and GE on the forum and in the know could give us an update . . .

[lomapaseo]

Torquelink

Thanks, that really answered my question:ok:

[RB Thruster]

There was indeed a lot going on when BA ordered the GE90 on their first 777s. GE made a high offer for the BA engine overhaul shop, supposedly as a separate deal (yeah right..) but also if I remember right, Lord King was annoyed with the UK government for allowing more US airlines into Heathrow? The combination of those plus a very good commercial offer from GE got them the deal, or that is what we in Derby were told at the time.:ugh:

The result was a GE order on the 777 which caused a huge shock at RR...still us boys from Derby have done OK with the Trent family since!:D

[spilko]

Easy 69. Are you a fan of conspiracy theories? It is ridiculous to think that the decision not to put an engine on the ER and LR are linked to the roll-back events. RR was not aware of a problem on the Trent 800.

It should also be pointed out that there is yet no evidence that there is a problem with the Trent 800 engine.

The report clearly states "in the fuel path of the FOHE". Similarly the Y-MMM AAIB report states "ice in the fuel feed system". As the Trent 800 FOHE passed all its certification tests with respect to icing the question is how is the fuel system generating larger than expected quantities of ice.

The suggested operational changes are in response to the AAIB report which called for "operational changes to reduce the risk of ice formation".

There is still a long way to go before it is determined (if it ever will be) where the ice formed and where it is causing the blockage. Even if the blockage is at the FOHE it doesn't necessarily mean the problem is a Trent 800 problem. This is clear from the AAIB reports.

[WHBM]

All the discussion above about technical considerations and the GE exclusivity on the larger 777 models is a bit wide of the mark. It was a commercial negotiation driven by Boeing that led to this, based primarily on what would offer the best financial return to Boeing. Which is a fair enough way to go (well, as a sales person I would say that).

The 777-300ER has hit good sales targets for Boeing, but the 777-200LR has been a poor performer. It's a limited market for ultra long haul, as Airbus also demonstrate with the A340-500. Rolls Royce got the exclusivity on that by the way, it cuts both ways. It is not in the airframe manufacturers interest to have a limited-production model dissipate technical resources over two or three engine models, if they can avoid it.

It is, as always, an interesting spectator sport to see two supremely professional organisations slug it out commercially. For those who have been around longer the most surprising thing is the demise of Pratt & Whitney from former supreme leader to one who is steadily vanishing. It must be years since P&W actually made a New Business sale, all they are left with is a half share in the GP7200.

In the City AM financial world daily newspaper there was an informed story yesterday about financial difficulties at GE that are causing questions, especially at their leasing arm GE Capital, who have financed a good proportion of the world airliner fleet, so more to watch there.

[Torquelink]

WHBM

Agree re exclusivity - see my earlier post 21.

Re Pratt: maybe the PW1000G (GTF) technology will, eventually, see them dine at the top table again - they seem to think the technology would result in significant sfc improvements for big (80k/lb thrust) engines too?

Can't believe GE / GECAS are in any serious trouble - we'll all be holding onto our hats if they are . . .