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Boeing Links BA038 And Delta Rolls Royce Incidents  
User currently offlineSInGAPORE_AIR From United Kingdom, joined Nov 2000, 13745 posts, RR: 19
Posted (5 years 10 months 2 weeks 6 days 12 hours ago) and read 14483 times:

Didn't see this posted but I thought this would be of intrigue and interest to many so...



Boeing links Heathrow, Atlanta Trent 895 engine rollbacks

Boeing says "similar factors" were likely at play in two Trent 895 thrust rollback incidents on Boeing 777-200ER aircraft last year.

The airframer says water-ice accumulation in the fuel path of the engine fuel-oil heat exchanger systems in the powerplants appears to have played role in both situations.

Part of the fuel-oil heat exchanger, the tubes are located next to fluid lines carrying heated engine oil. From a design standpoint, the mutually beneficial system allows the engine oil to be cooled by the cold fuel while the fuel itself is heated for better combustion performance.

Under certain conditions however, Boeing engineers working in the laboratory have found that the heat generated by the Rolls-Royce designed fuel-oil heat exchanger is not adequate to prevent moisture in the fuel from freezing, a condition that tests have shown will produce ice the blocks the entrance of the fuel to the exchanger, starving the engines.

Boeing says that 777s powered by GE and Pratt & Whitney engines are not prone to the problem.

Rolls-Royce declined to comment on the incidents while the investigations are ongoing.

FlightGlobal


Anyone can fly, only the best Soar.
58 replies: All unread, showing first 25:
 
User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 1, posted (5 years 10 months 2 weeks 6 days 12 hours ago) and read 14453 times:

Ouchie! This is big...  headache 

Something tells me we will see an Emergency AD with a redesigned heat exchanger.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineCaptainsimon From United Kingdom, joined Nov 2006, 127 posts, RR: 0
Reply 2, posted (5 years 10 months 2 weeks 6 days 12 hours ago) and read 14427 times:

Very interesting, seems like a logical answer.
The long term fix will be a redesign of the heat exchange.


User currently offlineCharles79 From Puerto Rico, joined Mar 2007, 1331 posts, RR: 6
Reply 3, posted (5 years 10 months 2 weeks 6 days 11 hours ago) and read 14197 times:

For those of us who are not engineers does that mean that a possible avoidance of this phenomenon is simply to seek warmer temperatures? Or are there other atmospheric factors at play besides just temperature?

Either way it's a relieve to learn that both Boeing and RR are being diligent in the investigation and that thus far we don't have any fatal accidents as a result of this.


User currently offlineReggaebird From Jamaica, joined Nov 1999, 1176 posts, RR: 0
Reply 4, posted (5 years 10 months 2 weeks 6 days 7 hours ago) and read 13657 times:

Hmmmm. I think that this is more serious than the rash of IFSDs being experienced by the GE-90-115's on the 777-300ERs. Would it be prudent to just avoid flying on RR-equipped trip sevens that are flying very long routes?

User currently offlineEbbUK From , joined Dec 1969, posts, RR:
Reply 5, posted (5 years 10 months 2 weeks 6 days 7 hours ago) and read 13622 times:



Quoting Reggaebird (Reply 4):
Hmmmm. I think that this is more serious than the rash of IFSDs being experienced by the GE-90-115's on the 777-300ERs. Would it be prudent to just avoid flying on RR-equipped trip sevens that are flying very long routes?

Perhaps to avoid flying long routes on the T7 altogether would be more prudent still?


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5944 posts, RR: 11
Reply 6, posted (5 years 10 months 2 weeks 6 days 6 hours ago) and read 13470 times:



Quoting Charles79 (Reply 3):
For those of us who are not engineers does that mean that a possible avoidance of this phenomenon is simply to seek warmer temperatures?

In a word, yes.

Quoting Reggaebird (Reply 4):
Hmmmm. I think that this is more serious than the rash of IFSDs being experienced by the GE-90-115's on the 777-300ERs.

I agree wholeheartedly, if only because both engines on an aircraft are generally experiencing the same atmospheric conditions, i.e. temperature, and therefore in a situation where one engine loses fuel flow, the opposite engine on these aircraft is also VERY likely to lose fuel flow as well. The GE-90-115B incidents seem to be single-engine only shutdowns, leaving the other engine running. Still an issue, but not like this news.

Quoting Reggaebird (Reply 4):
Would it be prudent to just avoid flying on RR-equipped trip sevens that are flying very long routes?

Oh please, you're overreacting. Calm down, man! Stay rational! Don't lose your head! Now excuse me while I book my next flight across the Atlantic on a GE-powered 777. Not even kidding.

Quoting EbbUK (Reply 5):
Perhaps to avoid flying long routes on the T7 altogether would be more prudent still?

Haha, come now. Last I checked, Airbus A330s were plummeting dirt-ward in Australia A LOT lately, so we should probably avoid ALL airplanes made by ALL manufacturers!


User currently offlineIkramerica From United States of America, joined May 2005, 21582 posts, RR: 59
Reply 7, posted (5 years 10 months 2 weeks 6 days 6 hours ago) and read 13422 times:



Quoting AA737-823 (Reply 6):
Haha, come now. Last I checked, Airbus A330s were plummeting dirt-ward in Australia A LOT lately, so we should probably avoid ALL airplanes made by ALL manufacturers!

It's the only safe way to proceed, I guess. From now on, I drive. Soooo much safer…  Wink



Of all the things to worry about... the Wookie has no pants.
User currently offlineCpd From Australia, joined Jun 2008, 4881 posts, RR: 37
Reply 8, posted (5 years 10 months 2 weeks 6 days 6 hours ago) and read 13400 times:



Quoting Charles79 (Reply 3):
For those of us who are not engineers does that mean that a possible avoidance of this phenomenon is simply to seek warmer temperatures? Or are there other atmospheric factors at play besides just temperature?

Yes - that's one of the solutions if I remember correctly. Either through descending, or by changing course to seek expected warmer conditions.

At the time, I remember reading a Boeing publication that had a very detailed article about fuel temperature with regards to Boeing and its McDonnell Douglas inherited aircraft. This was one of the recommendations.

The article covered long distance polar flight operations. It talked about fuel freezing, airport readiness to accept emergency diversions, availability of suitable fuel types.


User currently offline474218 From United States of America, joined Oct 2005, 6340 posts, RR: 9
Reply 9, posted (5 years 10 months 2 weeks 6 days 6 hours ago) and read 13401 times:



Quoting Charles79 (Reply 3):
For those of us who are not engineers does that mean that a possible avoidance of this phenomenon is simply to seek warmer temperatures? Or are there other atmospheric factors at play besides just temperature?

The temperatures are fairly constant above 35,000 feet and not very warm!


User currently offlineTodaReisinger From Switzerland, joined Mar 2001, 2807 posts, RR: 1
Reply 10, posted (5 years 10 months 2 weeks 6 days 5 hours ago) and read 13326 times:

Seems very astonishing that such an error could occur. And how is it that it took so much time to find out what happened?

But main question: what can be done to overcome this problem?

What is "moisture in the fuel"? Couldn't it prevented?



I bitterly miss the livery that should never have been changed (repetition...)
User currently offlineOsiris30 From Barbados, joined Sep 2006, 3192 posts, RR: 25
Reply 11, posted (5 years 10 months 2 weeks 6 days 5 hours ago) and read 13216 times:



Quoting TodaReisinger (Reply 10):
And how is it that it took so much time to find out what happened?

Because it's a very small part of a huge system, that only happens in very specific circumstances, with one of three different engines. In short it is a needle in a haystack and is somewhat amazing it was ever precisely identified. It is incredibly rare (witness two incidents in many thousands of flights).

Quoting TodaReisinger (Reply 10):
But main question: what can be done to overcome this problem?

Change the heat exchanger on the RR engines long term.

Quoting TodaReisinger (Reply 10):
What is "moisture in the fuel"? Couldn't it prevented?

In this case I think they mean water. And it is always present to some extent, but can be reduced depending on the refining process/controls.



I don't care what you think of my opinion. It's my opinion, so have a nice day :)
User currently offlineBreaker1011 From United States of America, joined Nov 2007, 938 posts, RR: 2
Reply 12, posted (5 years 10 months 2 weeks 6 days 5 hours ago) and read 13183 times:

Who are the major carriers flying T7's with RR powerplants? (outside of BA/DL of course)


Life's tough. It's even tougher if you're stupid. J. Wayne
User currently offlineReggaebird From Jamaica, joined Nov 1999, 1176 posts, RR: 0
Reply 13, posted (5 years 10 months 2 weeks 6 days 5 hours ago) and read 13144 times:



Quoting AA737-823 (Reply 6):
Quoting EbbUK (Reply 5):
Perhaps to avoid flying long routes on the T7 altogether would be more prudent still?

I wouldn't shy away from trip sevens flying across the Atlantic. I bet the challenges occur when these birds are up for extra long hours, i.e., for really extended periods. PEK-LON is about 10.5-11.5 hours and PVG-ATL is around 14.5-15.5 hours. I bet the ice buildup issue threshold is somewhere around the 9 hour mark. I have no scientific evidence...it just makes sense to me.


User currently offlineReggaebird From Jamaica, joined Nov 1999, 1176 posts, RR: 0
Reply 14, posted (5 years 10 months 2 weeks 6 days 5 hours ago) and read 13108 times:



Quoting Breaker1011 (Reply 12):
Who are the major carriers flying T7's with RR powerplants? (outside of BA/DL of course)

Singapore, American, Cathay come to mind.


User currently offlineReggaebird From Jamaica, joined Nov 1999, 1176 posts, RR: 0
Reply 15, posted (5 years 10 months 2 weeks 6 days 5 hours ago) and read 13075 times:



Quoting Breaker1011 (Reply 12):
Who are the major carriers flying T7's with RR powerplants? (outside of BA/DL of course)

Per the Rolls-Royce web site, "The Trent 800 is the market leading engine on the Boeing 777 with a 41 per cent share".


User currently offlineKELPkid From United States of America, joined Nov 2005, 6428 posts, RR: 3
Reply 16, posted (5 years 10 months 2 weeks 6 days 3 hours ago) and read 12947 times:



Quoting TodaReisinger (Reply 10):
What is "moisture in the fuel"? Couldn't it prevented?

Just how it sounds: water.

Jet fuel is a hygrometric substance, and will absorb a certain amount of water. Under certain conditions (like, for instance, cold soaking the fuel as happened in the BA accident of G-YMMM), the water will begin to form ice crystals and leave the solution.

There are some fuel additives made for business jets to prevent this, but they are expensive and very very toxic (look up the MSDS sheet on "Prist" sometime). Prist is the tradename of the most common one.

Prist is also a powerful biocide, and is also used in jet aircraft that don't fly frequently, as it kills various fungi and bacteria that can grow in jet fuel and cause problems as they digest the fuel (believe it or not, nature actually has little nasties that digest products like jet fuel!)  Smile



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 17, posted (5 years 10 months 2 weeks 6 days 2 hours ago) and read 12805 times:



Quoting KELPkid (Reply 1):
Something tells me we will see an Emergency AD with a redesigned heat exchanger.

I don't see it. The situation can be mitigated by procedure, so there's no need for an emergency AD. An AD that requires changing of the heat exchanger seems likely, but with operational procedure changes there's no reason not to give the AD a multi-year compliance time.

Quoting Charles79 (Reply 3):
For those of us who are not engineers does that mean that a possible avoidance of this phenomenon is simply to seek warmer temperatures?

Yes, although strictly speaking you just need to increase the temperature of the HX to melt the ice (i.e. throttle back).

Quoting TodaReisinger (Reply 10):

What is "moisture in the fuel"? Couldn't it prevented?

As others have said, it's just water. It can technically be prevented at the loading, but the tanks breath so you can never get rid of it entirely. Also, at the volumes involved in air transport, it's just not practical to get the concentration of water to zero at the uplift point.

Tom.


User currently offlineIkramerica From United States of America, joined May 2005, 21582 posts, RR: 59
Reply 18, posted (5 years 10 months 2 weeks 6 days 1 hour ago) and read 12684 times:



Quoting 474218 (Reply 9):
The temperatures are fairly constant above 35,000 feet and not very warm!

Not always, as last winter they were very, very cold, some of the coldest ever recorded, and at times, below the testing temperature of the aircraft during certification.



Of all the things to worry about... the Wookie has no pants.
User currently offlineBaroque From Australia, joined Apr 2006, 15380 posts, RR: 59
Reply 19, posted (5 years 10 months 2 weeks 6 days ago) and read 12659 times:



Quoting KELPkid (Reply 16):
Prist is also a powerful biocide, and is also used in jet aircraft that don't fly frequently, as it kills various fungi and bacteria that can grow in jet fuel and cause problems as they digest the fuel (believe it or not, nature actually has little nasties that digest products like jet fuel!)

Jet fuel is really yummy, not so many of those branched compounds as you get in lead free petrol. I just cannot stand those naphtheno-aromatic compounds though.

I am, personally, not even very keen on those naphthenic acids that you find in some crude feedstocks:
http://www.merichem.com/products_ser...t_literature/caustic_jet/index.php
Although naphthenic acids are naturally found in most crude oils, fortunately for refiners they create little processing difficulties because their concentration is typically quite low. However, there are several important crude oil sources in the world where this is not the case, such as in Peru and Venezuela in South America; Trinidad in the Caribbean; California and Louisiana in the USA; mainland China's Sheng Li and Xing Xiang crudes; and in some European crudes such as those produced in Romania, as well as new finds in the North Sea.

...
Jet fuels must meet very stringent international specifications because they are used by airlines all over the world who, regardless of where they land and refuel, must purchase quality and safe fuels. Among the numerous specifications are acidity, aromatics, olefins, naphthalene, smoke point, sulphur, mercaptan, freeze point, color, and water separation index.
.....
The refinery production of jet fuel varies from simply withdrawing a side stream product from the crude oil fractionator that requires no additional treating or cleanup, to caustic treating followed by water washing, salt drying, and clay filtration; and, finally, to hydrotreating the product so that it can meet all jet fuel specifications.

Hydrotreating requires a much greater capital investment (10 to 20 times) and involves much higher operating costs (20 to 50 times) than "wet treating", which is the phrase often used to denote caustic treating, with the attendant clean-up processes. For these reasons, refineries avoid hydrotreating whenever possible.

However, hydrotreating can produce jet fuel from most crude oils, whereas, wet treating is limited to jet fuels that already meet the specifications not affected by caustic treating. Table 1 provides a cost comparison of caustic.
Table I. Cost Comparisons: Caustic Treating vs. Hydrotreating


Maybe there is a problem with the Roller's heat exchangers, but I would like to see the specs of the fuels loaded in the two cases. There are so many variables.

Signed

A Greebly


User currently offlineBongodog1964 From United Kingdom, joined Oct 2006, 3682 posts, RR: 3
Reply 20, posted (5 years 10 months 2 weeks 5 days 21 hours ago) and read 11711 times:

To my mind the significant thing here, is that Boeing have gone public, with their theory; without having either RR the NTSB or UK Air Accident investigation sitting beside them.

This suggests that there is not a unaminous agreement that this is the cause of the BA038 accident.


User currently offlineJerseyFlyer From United Kingdom, joined May 2007, 676 posts, RR: 0
Reply 21, posted (5 years 10 months 2 weeks 5 days 20 hours ago) and read 11187 times:

The Flightglobal article also states:

"Boeing says that 777s powered by GE and Pratt & Whitney engines are not prone to the problem. "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," the letter states."

Why is this not a problem on A340 and A330 with Trent 600 and 700?

[Edited 2009-02-04 04:11:11]

User currently offlineNomadd22 From United States of America, joined Feb 2008, 1899 posts, RR: 0
Reply 22, posted (5 years 10 months 2 weeks 5 days 20 hours ago) and read 11130 times:

I thought the BA problem was from an extended decent at engine idle causing a low fuel flow rate, but the Delta flight was at cruise when it rolled back, so I guess that theory is out.

[Edited 2009-02-04 04:18:27]


Andy Goetsch
User currently offlineWorldTraveler From , joined Dec 1969, posts, RR:
Reply 23, posted (5 years 10 months 2 weeks 5 days 20 hours ago) and read 11130 times:

is this problem exclusive to the 895 or also the 892?

I believe there were pilot procedures put in place when ice was suspected on these a/c - or to help prevent it. Can someone list them?


User currently offlineNa From Germany, joined Dec 1999, 10817 posts, RR: 9
Reply 24, posted (5 years 10 months 2 weeks 5 days 19 hours ago) and read 10830 times:

There have been many engine problems on 777s lately, thank god all with lucky outcome so far.

25 SpeedBirdA380 : Yes and the fact that RR refused to comment also suggests this announcement was a surprise to them. Thats what I thought. Perhaps the particular syst
26 TISTPAA727 : Reminds me of the UA and US 737 crashes where the servo valve failed when super heated hydraulic fluid entered a very cold valve and caused it to sto
27 Francoflier : Not always that simple. Seeking higher fuel temperature usually means either accelerating or descending (sometimes climbing) to an altitude that is f
28 JohnClipper : So the problem is with RR, not Boeing, correct?
29 SpeedBirdA380 : This is what Boeing are claiming - yes. But neither Rolls Royce,NTSB or UK Air Accident investigation have commented on it and have not yet backed Bo
30 Baroque : If you know the fuel composition that caused the problem, that should not be too difficult. From the article: Under certain conditions however, Boein
31 Osiris30 : Why is the engine problem in a Ford F150 not applicable to a Ferrari? They are different power plants with significant differences, in significantly
32 Revelation : If you can use the word "hygrometric" you know more about chemistry than me! How is this stuff different than "dry gas" one adds to an automobile fue
33 FlyASAGuy2005 : I'm not an engineer so this all sounds so foreign to me as the extent of my systems knowledge is on the 152s/72s and DA40s but it just takes me back b
34 Post contains links Revelation : Wikipedia's BA038 Page says: I followed the cited reference: http://www.aaib.dft.gov.uk/cms_resources/G-YMMM%20Interim%20Report.pdf and it too didn't
35 Bongodog1964 : I just can't buy this scenario. If Boeings labs felt they had achived a breakthrough in the investigation, the other agencies invloved would have the
36 OldAeroGuy : It's very probable they were involved but haven't chosen to announce anything at this time. Boeing may be compelled to make an announcement due to pr
37 Pnh2atl : At DL we have implemented some operational procedures for our 777 w/ the RR engines based on fuel temps. It is not piratical to fly them in warmer air
38 Osiris30 : And they probably did, but as OleAeroGuy pointed out: Boeing has a duty as a publically traded company to release any news which may have an impact o
39 Atomsareenough : No, that would only be piratical if DL commandeered another airline's planes to fly them in warmer air
40 KELPkid : I don't know the answer to that, but I suspect that the answer is "yes." I would hypothesize that Prist, amongst it's chemical properties, bridges th
41 TristarSteve : The procedures come under an AD. FAA AD 2008-19-04. Perhaps one of you knows how to get this on here. Basically the procedures call for increasing th
42 FrmrCAPCADET : I concur, particularly with the "full system" comment. An analogous situation arose with the Ford Explorer and a certain Firestone (I believe) tire.
43 Post contains links Tdscanuck : Airbus and Boeing use fairly different fuel system architectures. As I understand it, the prolonged cruise in cold temperatures was also what caused
44 Osiris30 : Correct in the most literal sense of what I posted, but, if Boeing discovers an issue such as this they have a requirement to inform their customers,
45 Cubastar : Listen to these two fellows, guys. All of the back and forth about whether or not RR or any of the airlines operating the Trent are aware and involve
46 Airtechy : So if the "water droplets" are eliminated by transferred heat in the heat exchanger, and the engines won't spool up to generate more heat, how do you
47 Osiris30 : Water isn't the problem, small volumes in the jet fuel do little/nothing to a modern jet engine. Frozen water is as it can form blockages. Eventually
48 Tdscanuck : The engines don't need to spool up to generate more heat, you just need to change the heat balance in the heat exchanger. The heat exchanger is takin
49 Nomadd22 : I'd thought that the problem was the fuel cooling down between the exchanger and the engines, since the tank temps were ok. So, either I'm way off, o
50 Airtechy : Thanks for the explanation. You can't land below a certain power level/fuel flow though, so I guess the trick is to get rid of the water droplets ear
51 Tdscanuck : Once you're passed the exchanger, you shouldn't have a problem. The preliminary reports report ice clogging the HX itself, which must happen on the i
52 Wjcandee : Nah. This finding by Boeing was actually predicted by a member on here several weeks ago, when describing the difference in the RR heat exchanger set
53 AirNZ : Whilst I can understand what you're saying I would tend to disagree with the method. Whilst having a duty to protect lives, they also have a duty to
54 Osiris30 : Does it matter? Do you think any other companies would behave in any different fashion? At the end of the day, even if Boeing and EADS are run by the
55 Par13del : "Similar factors were likely at play" That is what I read in the article linked at the start of this thread, I admit to not having done it sooner but
56 Post contains links DingDong : Regarding #1 and #2, Boeing has not made a public determination as to what caused the BA038 crash. That will have to come from the UK AAIB in due tim
57 OldAeroGuy : Nor does it mean that it isn't a 'fact' or that it is not 'reproducable'. It's hard to understand why you're having an issue with this.
58 Tdscanuck : As far as I know, they haven't released an SB yet. The AD is the only official released material I've seen. An SB would drive a design change, and th
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