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lightsaber
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Re: Is the RR 787 engine problem fixed yet?

Thu Oct 15, 2020 3:35 pm

I missed this link. Basically, parts still going into fleet through 2020, over half the B/C fleet upgraded and TEN fleet to be upgraded by 1H2021.

https://www.ainonline.com/aviation-news ... ent-xwb-84

GE is making heavier fans, but they do better aerodynamically. Pratt made risk decisions on the PW1100G.
Dry weight PW1100G 2857.6 kg
Weight LEAP-1A: 3,008 (includes maybe 50kg of fluids)

https://www.easa.europa.eu/document-lib ... easaime093

https://www.easa.europa.eu/document-lib ... e/easae110

GE had to take the risk of new materials due to a 5-stage turbine. Pratt is looking to a material change to 3D print low turbines, so I'll stand by the statement.

Everyone, please take a step back and realize each company's architecture decision drives their R&D spending.

GE us aligned to Boeing and due to some spectacular gearbox explosions on the DC-7, anyone from Douglas or mentored by Douglas is scared of gearboxes. So GE invested in variable cycle, CMCs, and when their math said the LEAP-1A needed a five stage low turbine, a weight reduction. But then GE realized the Pratt GTFs were using a low Turbine trick beyond the GTF (I cannot disclose due to an ancient NDA) and implimented in the LEAP-1A and GE9x. GE has always invested more in compressor technology, partially as they just have a good team. GE has made huge mistakes on counter rotation on military engines, so burned twice, thrice shy? (F100 & F120, which cost them both contracts, yes I know how good the F110 is, but there is a reason a new engine was required while Pratt develops the F101). GE us so far along on electrical subsystems, it allowed them to go crazy complicated on the GE9x. I seriously believe every Whittle subsystem patent idea from the 1950s was *finally* implimented on the GE9x, so it isn't like RR and Pratt don't know what do do, GE is just a clear leader.

Pratt going GTF means nothing matters more than the efficiency of the low Turbine, so huge investment there. Pratt figured out an aerodynamic trick with fans which GE mostly picked up on due to the GP7200. Also, Pratt has their own in house CFD (computational fluid dynamics) code that allows much larger grid sizes, hence why Pratt spends more time on system optimization (partially as not doing that on the PW6000 was a HUGE mistake). I came out of Pratt (a long time ago) and thus understand their obsession with counter rotation. There avoidance of system design of subsystems is why Pratt had issues IMHO.

The triple spool makes RR a jack of all trades. They know all the tricks (the non material ones mostly invented by Whittle a long time ago, I'm amazed how much of my career was figuring out if we could impliment a Whittle patent) and usually spread out the R&D. There only weakness is combustors, but that means they do not take risks, so they do not have issues with combustors.

But not focusing, RR fell behind in Turbine tech and hence the issues. The compressor issues wouldn't even be discussed if the T1000 issue wasn't sucking the company's money and prevented focusing on fuel burn PiPs.

I wish Raytheon Technologies hadn't gone on a buying spree and could afford to buy RR. But $92 billion of debt is a lot. I'm very curious to see the October 27th quarterly report for Pratt's parent company. When is RR reporting 3Q2020?

Lightsaber
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SRQLOT
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Re: Is the RR 787 engine problem fixed yet?

Thu Oct 15, 2020 5:57 pm

777Mech wrote:
SRQLOT wrote:
777Mech wrote:

Why put engines on something that isn't needed?



Well yes of course, that’s why RR got a lifeline in this crisis. RR has more time to fix the issue without worrying about additional payouts. So really the issue has not been solved yet, it wouldn’t matter that the aircraft are sitting on the ground for a year now, they still would have gotten the engines if RR had them.


Naturally RR has had time, but no airline in their right mind would install engines on a plane they don't need. Time on those LLPs in those engines start as soon engines are on wing, regardless if the plane flies. It's best to leave them on the stand until absolutely needed.


Thanks! Yeah definitely not well versed in maintenance of aircraft so thank you for that information.
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Dalmd88
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Re: Is the RR 787 engine problem fixed yet?

Fri Oct 16, 2020 1:16 pm

I think Rolls has turned the corner on the T1000 issues. That is as long as the new blade sets meet the expectations over the long term.

We were told that as of June there were no more AOG aircraft in the system that Rolls was responsible for. The work through the shops has continued since that time to keep up with planned removals and keeping the spares bins full. I don't know how many more engines in the fleet are still due for blade changes, but at least now their are enough spares to keep up with the removals. The parking of the fleets for the virus has helped, but Rolls was on the path to reach the June milestone back before the world shutdown.

For the 7000 fleet things are even better. There are less engines in the fleet that required the blade set changes, since the new fix came near the beginning of production. The Singapore shop began work earlier this year and the Delta shop will be doing work this fall.
 
2175301
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Re: Is the RR 787 engine problem fixed yet?

Fri Oct 16, 2020 3:56 pm

x1234 wrote:
Is the RR 787 engine problem fixed yet? Have they used A350 parts and practices to the 787? Reason I ask is that I know Air China pre-pandemic moved their PEK-EWR/YUL flights off the 789 and onto the 77W because of the engine problem causing trans-polar ETOPS problems. I hope it resolves soon because the 789 is perfect for serving thinner city pairs in the world.



I'd like to answer the OP's question: RR believes that they have a fix. In reality it will likely be about another 4-5 years before we know if it really worked. Some of these issues take years to show up.

Have a great day,
 
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Revelation
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Re: Is the RR 787 engine problem fixed yet?

Fri Oct 16, 2020 4:29 pm

2175301 wrote:
x1234 wrote:
Is the RR 787 engine problem fixed yet? Have they used A350 parts and practices to the 787? Reason I ask is that I know Air China pre-pandemic moved their PEK-EWR/YUL flights off the 789 and onto the 77W because of the engine problem causing trans-polar ETOPS problems. I hope it resolves soon because the 789 is perfect for serving thinner city pairs in the world.

I'd like to answer the OP's question: RR believes that they have a fix. In reality it will likely be about another 4-5 years before we know if it really worked. Some of these issues take years to show up.

I think we have the answer for the problems RR is already actively addressing:

lightsaber wrote:
I missed this link. Basically, parts still going into fleet through 2020, over half the B/C fleet upgraded and TEN fleet to be upgraded by 1H2021.

https://www.ainonline.com/aviation-news ... ent-xwb-84

Details:

Rolls said it has introduced certain solutions on a “fast-track basis” to improve the Trent 1000’s in-service durability. More than 99 percent of the flying fleet has received an improved intermediate pressure turbine blade. Meanwhile, engineers continue to fit Trent 1000 TEN and Package C engines with redesigned IPC blades, which the company expects to make available for the Package B engines in the fourth quarter. Rolls also reported that it should complete the Trent 1000 TEN and Package C blade roll program by the end of next year. For the Package B and C engines, it has upgraded more than 50 percent of the fleet with improved high-pressure turbine blades.

Rolls continues endurance testing a final durability issue with the Trent 1000 TEN's high-pressure turbine blades, identified during a “rigorous root cause investigation and design process,” according to the company. “We are now over three-quarters of the way through this test and remain on track for its incorporation into the fleet by the end of H1 2021,” it reported.

So T1000 seems it will take till the end of 2021 to be 100% clear.

We know there are concerns with the Trent XWB-84 IPC as well:

Rolls-Royce says that fatigue cracking has been discovered in stage one intermediate pressure compressor (IPC) blades on certain higher-cycle XWB-84 engines.

Ref: https://www.flightglobal.com/engines/a3 ... 08.article

TFA tells us they won't know the root cause till around Xmas time, but they feel it's unrelated to the T1000 problems.

Yet there are increased inspections to do in the mean time, and presumably more work at the next planned shop visit.

Hopefully that is the extent of it, so far it's just a costly wear issue as opposed to an aircraft on the ground situation.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
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2175301
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Re: Is the RR 787 engine problem fixed yet?

Fri Oct 16, 2020 7:13 pm

Revelation wrote:
2175301 wrote:
x1234 wrote:
Is the RR 787 engine problem fixed yet? Have they used A350 parts and practices to the 787? Reason I ask is that I know Air China pre-pandemic moved their PEK-EWR/YUL flights off the 789 and onto the 77W because of the engine problem causing trans-polar ETOPS problems. I hope it resolves soon because the 789 is perfect for serving thinner city pairs in the world.

I'd like to answer the OP's question: RR believes that they have a fix. In reality it will likely be about another 4-5 years before we know if it really worked. Some of these issues take years to show up.

I think we have the answer for the problems RR is already actively addressing:

lightsaber wrote:
I missed this link. Basically, parts still going into fleet through 2020, over half the B/C fleet upgraded and TEN fleet to be upgraded by 1H2021.

https://www.ainonline.com/aviation-news ... ent-xwb-84

Details:

Rolls said it has introduced certain solutions on a “fast-track basis” to improve the Trent 1000’s in-service durability. More than 99 percent of the flying fleet has received an improved intermediate pressure turbine blade. Meanwhile, engineers continue to fit Trent 1000 TEN and Package C engines with redesigned IPC blades, which the company expects to make available for the Package B engines in the fourth quarter. Rolls also reported that it should complete the Trent 1000 TEN and Package C blade roll program by the end of next year. For the Package B and C engines, it has upgraded more than 50 percent of the fleet with improved high-pressure turbine blades.

Rolls continues endurance testing a final durability issue with the Trent 1000 TEN's high-pressure turbine blades, identified during a “rigorous root cause investigation and design process,” according to the company. “We are now over three-quarters of the way through this test and remain on track for its incorporation into the fleet by the end of H1 2021,” it reported.

So T1000 seems it will take till the end of 2021 to be 100% clear.

We know there are concerns with the Trent XWB-84 IPC as well:

Rolls-Royce says that fatigue cracking has been discovered in stage one intermediate pressure compressor (IPC) blades on certain higher-cycle XWB-84 engines.

Ref: https://www.flightglobal.com/engines/a3 ... 08.article

TFA tells us they won't know the root cause till around Xmas time, but they feel it's unrelated to the T1000 problems.

Yet there are increased inspections to do in the mean time, and presumably more work at the next planned shop visit.

Hopefully that is the extent of it, so far it's just a costly wear issue as opposed to an aircraft on the ground situation.


Sorry Revelation... I'll let time tell us if the fixes work. Remember that supposedly the engine was OK up front based on testing. I've long forgotten the number of different issues that developed when in service. I'll stick with my answer above: We will know if the fixes actually worked in 4-5 years. There's really no shortcut to long term reliability testing - except actual service life; as many manufacturers have discovered.

Have a great day,
 
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ElroyJetson
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Re: Is the RR 787 engine problem fixed yet?

Fri Oct 16, 2020 7:28 pm

lightsaber wrote:
I missed this link. Basically, parts still going into fleet through 2020, over half the B/C fleet upgraded and TEN fleet to be upgraded by 1H2021.

https://www.ainonline.com/aviation-news ... ent-xwb-84

GE is making heavier fans, but they do better aerodynamically. Pratt made risk decisions on the PW1100G.
Dry weight PW1100G 2857.6 kg
Weight LEAP-1A: 3,008 (includes maybe 50kg of fluids)

https://www.easa.europa.eu/document-lib ... easaime093

https://www.easa.europa.eu/document-lib ... e/easae110

GE had to take the risk of new materials due to a 5-stage turbine. Pratt is looking to a material change to 3D print low turbines, so I'll stand by the statement.

Everyone, please take a step back and realize each company's architecture decision drives their R&D spending.

GE us aligned to Boeing and due to some spectacular gearbox explosions on the DC-7, anyone from Douglas or mentored by Douglas is scared of gearboxes. So GE invested in variable cycle, CMCs, and when their math said the LEAP-1A needed a five stage low turbine, a weight reduction. But then GE realized the Pratt GTFs were using a low Turbine trick beyond the GTF (I cannot disclose due to an ancient NDA) and implimented in the LEAP-1A and GE9x. GE has always invested more in compressor technology, partially as they just have a good team. GE has made huge mistakes on counter rotation on military engines, so burned twice, thrice shy? (F100 & F120, which cost them both contracts, yes I know how good the F110 is, but there is a reason a new engine was required while Pratt develops the F101). GE us so far along on electrical subsystems, it allowed them to go crazy complicated on the GE9x. I seriously believe every Whittle subsystem patent idea from the 1950s was *finally* implimented on the GE9x, so it isn't like RR and Pratt don't know what do do, GE is just a clear leader.

Pratt going GTF means nothing matters more than the efficiency of the low Turbine, so huge investment there. Pratt figured out an aerodynamic trick with fans which GE mostly picked up on due to the GP7200. Also, Pratt has their own in house CFD (computational fluid dynamics) code that allows much larger grid sizes, hence why Pratt spends more time on system optimization (partially as not doing that on the PW6000 was a HUGE mistake). I came out of Pratt (a long time ago) and thus understand their obsession with counter rotation. There avoidance of system design of subsystems is why Pratt had issues IMHO.

The triple spool makes RR a jack of all trades. They know all the tricks (the non material ones mostly invented by Whittle a long time ago, I'm amazed how much of my career was figuring out if we could impliment a Whittle patent) and usually spread out the R&D. There only weakness is combustors, but that means they do not take risks, so they do not have issues with combustors.

But not focusing, RR fell behind in Turbine tech and hence the issues. The compressor issues wouldn't even be discussed if the T1000 issue wasn't sucking the company's money and prevented focusing on fuel burn PiPs.

I wish Raytheon Technologies hadn't gone on a buying spree and could afford to buy RR. But $92 billion of debt is a lot. I'm very curious to see the October 27th quarterly report for Pratt's parent company. When is RR reporting 3Q2020?

Lightsaber



From a physics perspective the greater the temperature variance between the engine core and the bypass air would theoretically improve performance and efficiency. When you look at core engine temps in jet engines from the first turbojets until today, there have been dramatic increases in core temps and hence efficiency.

However, I know manufacturers have been butting up against material limits for quite a while. Who in your opinion has the lead in material technology? I know many things go into jet turbine performance, but a significant advantage in materials by either Pratt, GE, or RR could really make a major difference.

Thanks.
707 717 727 72S 737 733 737-700 747 757 753 767-300 764 A319 A320 DC-9-10 DC-9-30 DC-9-50, MD-82 MD-88 MD-90 DC-10-10 DC-10-40 F-100
 
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Re: Is the RR 787 engine problem fixed yet?

Fri Oct 16, 2020 10:35 pm

ElroyJetson wrote:
lightsaber wrote:
I missed this link. Basically, parts still going into fleet through 2020, over half the B/C fleet upgraded and TEN fleet to be upgraded by 1H2021.

https://www.ainonline.com/aviation-news ... ent-xwb-84

GE is making heavier fans, but they do better aerodynamically. Pratt made risk decisions on the PW1100G.
Dry weight PW1100G 2857.6 kg
Weight LEAP-1A: 3,008 (includes maybe 50kg of fluids)

https://www.easa.europa.eu/document-lib ... easaime093

https://www.easa.europa.eu/document-lib ... e/easae110

GE had to take the risk of new materials due to a 5-stage turbine. Pratt is looking to a material change to 3D print low turbines, so I'll stand by the statement.

Everyone, please take a step back and realize each company's architecture decision drives their R&D spending.

GE us aligned to Boeing and due to some spectacular gearbox explosions on the DC-7, anyone from Douglas or mentored by Douglas is scared of gearboxes. So GE invested in variable cycle, CMCs, and when their math said the LEAP-1A needed a five stage low turbine, a weight reduction. But then GE realized the Pratt GTFs were using a low Turbine trick beyond the GTF (I cannot disclose due to an ancient NDA) and implimented in the LEAP-1A and GE9x. GE has always invested more in compressor technology, partially as they just have a good team. GE has made huge mistakes on counter rotation on military engines, so burned twice, thrice shy? (F100 & F120, which cost them both contracts, yes I know how good the F110 is, but there is a reason a new engine was required while Pratt develops the F101). GE us so far along on electrical subsystems, it allowed them to go crazy complicated on the GE9x. I seriously believe every Whittle subsystem patent idea from the 1950s was *finally* implimented on the GE9x, so it isn't like RR and Pratt don't know what do do, GE is just a clear leader.

Pratt going GTF means nothing matters more than the efficiency of the low Turbine, so huge investment there. Pratt figured out an aerodynamic trick with fans which GE mostly picked up on due to the GP7200. Also, Pratt has their own in house CFD (computational fluid dynamics) code that allows much larger grid sizes, hence why Pratt spends more time on system optimization (partially as not doing that on the PW6000 was a HUGE mistake). I came out of Pratt (a long time ago) and thus understand their obsession with counter rotation. There avoidance of system design of subsystems is why Pratt had issues IMHO.

The triple spool makes RR a jack of all trades. They know all the tricks (the non material ones mostly invented by Whittle a long time ago, I'm amazed how much of my career was figuring out if we could impliment a Whittle patent) and usually spread out the R&D. There only weakness is combustors, but that means they do not take risks, so they do not have issues with combustors.

But not focusing, RR fell behind in Turbine tech and hence the issues. The compressor issues wouldn't even be discussed if the T1000 issue wasn't sucking the company's money and prevented focusing on fuel burn PiPs.

I wish Raytheon Technologies hadn't gone on a buying spree and could afford to buy RR. But $92 billion of debt is a lot. I'm very curious to see the October 27th quarterly report for Pratt's parent company. When is RR reporting 3Q2020?

Lightsaber



From a physics perspective the greater the temperature variance between the engine core and the bypass air would theoretically improve performance and efficiency. When you look at core engine temps in jet engines from the first turbojets until today, there have been dramatic increases in core temps and hence efficiency.

However, I know manufacturers have been butting up against material limits for quite a while. Who in your opinion has the lead in material technology? I know many things go into jet turbine performance, but a significant advantage in materials by either Pratt, GE, or RR could really make a major difference.

Thanks.

GE is a few years ahead in CMCs tor combustors and turbine inlet guide vanes. No one can make a CMC turbine blade yet (ironically, the material must be much denser, to be strong enough to handle the strain of the rotating parts).

But CMCs wouldn't fix the issues for RR. Not in an intermediate turbine.

Materials help, but less than a GTF, IMHO.

The issue is RR switched turbine styles as they had taken the shrouded turbine as far is it could go and an unshrouded turbine on the intermediate turbine provided more efficiency. So they were dealing with material and basic architecture changes at the same time.

To others:

I believe the fixes being introduced will work. It is a question of getting the parts out fast enough to support a large in service fleet.

Lightsaber
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Revelation
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Re: Is the RR 787 engine problem fixed yet?

Sat Oct 17, 2020 3:36 pm

ElroyJetson wrote:
From a physics perspective the greater the temperature variance between the engine core and the bypass air would theoretically improve performance and efficiency. When you look at core engine temps in jet engines from the first turbojets until today, there have been dramatic increases in core temps and hence efficiency.

However, I know manufacturers have been butting up against material limits for quite a while. Who in your opinion has the lead in material technology? I know many things go into jet turbine performance, but a significant advantage in materials by either Pratt, GE, or RR could really make a major difference.

You also might want to look at not just change in temperature and how the material can absorb it, but look at thermodynamics and see how the change in temperature is addressed by cooling. As noted above a lot of work is being done in this area.
Wake up to find out that you are the eyes of the world
The heart has its beaches, its homeland and thoughts of its own
Wake now, discover that you are the song that the morning brings
The heart has its seasons, its evenings and songs of its own
 
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Re: Is the RR 787 engine problem fixed yet?

Sun Oct 18, 2020 11:37 am

2175301 wrote:
We will know if the fixes actually worked in 4-5 years. There's really no shortcut to long term reliability testing - except actual service life;

A lot is luck.
But luck favours those who put a lot of effort.
(Not my thought, but I don't remember where I read it.)
Why can't the world be a little bit more autistic?
 
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ElroyJetson
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Re: Is the RR 787 engine problem fixed yet?

Sun Oct 18, 2020 5:02 pm

Revelation wrote:
ElroyJetson wrote:
From a physics perspective the greater the temperature variance between the engine core and the bypass air would theoretically improve performance and efficiency. When you look at core engine temps in jet engines from the first turbojets until today, there have been dramatic increases in core temps and hence efficiency.

However, I know manufacturers have been butting up against material limits for quite a while. Who in your opinion has the lead in material technology? I know many things go into jet turbine performance, but a significant advantage in materials by either Pratt, GE, or RR could really make a major difference.

You also might want to look at not just change in temperature and how the material can absorb it, but look at thermodynamics and see how the change in temperature is addressed by cooling. As noted above a lot of work is being done in this area.



Absolutely. I know an issue on some fan blades has been the micro holes used for cooling that were leading to rapid and unplanned deterioration of the blades. It is a combination of material science, engineering, and basic thermodynamics.

But the underlying principle of physics in this instance are immutable. Heat must always go to cold, never the reverse. The greater temperature difference between the bypass air and engine core the more work the engine can do. The exact same principle holds for internal combustion engines, steam engines, and gas turbines.

Hurricanes work on the identical principle. The "fuel" is warm ocean water. The greater the temperature difference between the ocean water and the upper atmosphere the more powerful the hurricane. I doubt many meteorologists truly understand the physics behind how hurricanes work. Jet engines work on the identical principle.
707 717 727 72S 737 733 737-700 747 757 753 767-300 764 A319 A320 DC-9-10 DC-9-30 DC-9-50, MD-82 MD-88 MD-90 DC-10-10 DC-10-40 F-100
 
JayinKitsap
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Re: Is the RR 787 engine problem fixed yet?

Sun Oct 18, 2020 6:40 pm

ElroyJetson wrote:
Revelation wrote:
ElroyJetson wrote:
From a physics perspective the greater the temperature variance between the engine core and the bypass air would theoretically improve performance and efficiency. When you look at core engine temps in jet engines from the first turbojets until today, there have been dramatic increases in core temps and hence efficiency.

However, I know manufacturers have been butting up against material limits for quite a while. Who in your opinion has the lead in material technology? I know many things go into jet turbine performance, but a significant advantage in materials by either Pratt, GE, or RR could really make a major difference.

You also might want to look at not just change in temperature and how the material can absorb it, but look at thermodynamics and see how the change in temperature is addressed by cooling. As noted above a lot of work is being done in this area.



Absolutely. I know an issue on some fan blades has been the micro holes used for cooling that were leading to rapid and unplanned deterioration of the blades. It is a combination of material science, engineering, and basic thermodynamics.

But the underlying principle of physics in this instance are immutable. Heat must always go to cold, never the reverse. The greater temperature difference between the bypass air and engine core the more work the engine can do. The exact same principle holds for internal combustion engines, steam engines, and gas turbines.

Hurricanes work on the identical principle. The "fuel" is warm ocean water. The greater the temperature difference between the ocean water and the upper atmosphere the more powerful the hurricane. I doubt many meteorologists truly understand the physics behind how hurricanes work. Jet engines work on the identical principle.


Most engineers have a poor grasp on Thermodynamics, when I was in engineering at U Mich (1977) Thermo 310 was the killer class to weed out those from the real engineering programs - Civil, Structural, Mechanical, Petroleum, Auto, Nuclear, and Nav Arch. Filling the Construction Management, Planning, Soils, Wastewater, and Surveying where any more Thermo was not required.

PS Say hi to Judy for me.
 
RB211trent
Posts: 163
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Re: Is the RR 787 engine problem fixed yet?

Sun Oct 18, 2020 7:04 pm

lightsaber wrote:
ElroyJetson wrote:
lightsaber wrote:
I missed this link. Basically, parts still going into fleet through 2020, over half the B/C fleet upgraded and TEN fleet to be upgraded by 1H2021.

https://www.ainonline.com/aviation-news ... ent-xwb-84

GE is making heavier fans, but they do better aerodynamically. Pratt made risk decisions on the PW1100G.
Dry weight PW1100G 2857.6 kg
Weight LEAP-1A: 3,008 (includes maybe 50kg of fluids)

https://www.easa.europa.eu/document-lib ... easaime093

https://www.easa.europa.eu/document-lib ... e/easae110

GE had to take the risk of new materials due to a 5-stage turbine. Pratt is looking to a material change to 3D print low turbines, so I'll stand by the statement.

Everyone, please take a step back and realize each company's architecture decision drives their R&D spending.

GE us aligned to Boeing and due to some spectacular gearbox explosions on the DC-7, anyone from Douglas or mentored by Douglas is scared of gearboxes. So GE invested in variable cycle, CMCs, and when their math said the LEAP-1A needed a five stage low turbine, a weight reduction. But then GE realized the Pratt GTFs were using a low Turbine trick beyond the GTF (I cannot disclose due to an ancient NDA) and implimented in the LEAP-1A and GE9x. GE has always invested more in compressor technology, partially as they just have a good team. GE has made huge mistakes on counter rotation on military engines, so burned twice, thrice shy? (F100 & F120, which cost them both contracts, yes I know how good the F110 is, but there is a reason a new engine was required while Pratt develops the F101). GE us so far along on electrical subsystems, it allowed them to go crazy complicated on the GE9x. I seriously believe every Whittle subsystem patent idea from the 1950s was *finally* implimented on the GE9x, so it isn't like RR and Pratt don't know what do do, GE is just a clear leader.

Pratt going GTF means nothing matters more than the efficiency of the low Turbine, so huge investment there. Pratt figured out an aerodynamic trick with fans which GE mostly picked up on due to the GP7200. Also, Pratt has their own in house CFD (computational fluid dynamics) code that allows much larger grid sizes, hence why Pratt spends more time on system optimization (partially as not doing that on the PW6000 was a HUGE mistake). I came out of Pratt (a long time ago) and thus understand their obsession with counter rotation. There avoidance of system design of subsystems is why Pratt had issues IMHO.

The triple spool makes RR a jack of all trades. They know all the tricks (the non material ones mostly invented by Whittle a long time ago, I'm amazed how much of my career was figuring out if we could impliment a Whittle patent) and usually spread out the R&D. There only weakness is combustors, but that means they do not take risks, so they do not have issues with combustors.

But not focusing, RR fell behind in Turbine tech and hence the issues. The compressor issues wouldn't even be discussed if the T1000 issue wasn't sucking the company's money and prevented focusing on fuel burn PiPs.

I wish Raytheon Technologies hadn't gone on a buying spree and could afford to buy RR. But $92 billion of debt is a lot. I'm very curious to see the October 27th quarterly report for Pratt's parent company. When is RR reporting 3Q2020?

Lightsaber



From a physics perspective the greater the temperature variance between the engine core and the bypass air would theoretically improve performance and efficiency. When you look at core engine temps in jet engines from the first turbojets until today, there have been dramatic increases in core temps and hence efficiency.

However, I know manufacturers have been butting up against material limits for quite a while. Who in your opinion has the lead in material technology? I know many things go into jet turbine performance, but a significant advantage in materials by either Pratt, GE, or RR could really make a major difference.

Thanks.

GE is a few years ahead in CMCs tor combustors and turbine inlet guide vanes. No one can make a CMC turbine blade yet (ironically, the material must be much denser, to be strong enough to handle the strain of the rotating parts).

But CMCs wouldn't fix the issues for RR. Not in an intermediate turbine.

Materials help, but less than a GTF, IMHO.

The issue is RR switched turbine styles as they had taken the shrouded turbine as far is it could go and an unshrouded turbine on the intermediate turbine provided more efficiency. So they were dealing with material and basic architecture changes at the same time.

To others:

I believe the fixes being introduced will work. It is a question of getting the parts out fast enough to support a large in service fleet.

Lightsaber

RR does not use a shroudless blade on any IP turbine. Only on the xwb97 does it use a Shroudless HPT blade.

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