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lightsaber
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GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 1:15 am

I refuse to give out e-mail, so I haven't read the full article, but it looks like the engine for the 777X has a delay.

http://aviationweek.com/commercial-avia ... cing-delay

General Electric Aviation has been forced to delay first flight of the GE9X engine for Boeing’s 777X flagship program after the late discovery of a minor design issue with the new turbofan as well as maintenance-related problems with the CF6 engines powering the company’s 747-400 flying testbed.

I've been in flight test. In no way is a flight test program delayed for CF6 engine maintenance. GE is the vendor of the CF6! Testbed engines are maintained for an always engine out condition (the engine under test is routinely shut off). Does GE suddenly lack backup CF6 engines? I doubt it.

So what is the issue with the GE9X. I have no idea.

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zeke
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 4:45 am

Rumour I heard from a large airline in the Middle East is they had a blade failure and it may impact ETDO at EIS. Obviously if proves to be true a sensitive subject so I guess they will be doing their very best to resolve it before then through further testing.
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hayzel777
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 6:50 am

Apparently the vanes' design is no good and they needed a design change to it.
 
WIederling
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 6:52 am

zeke wrote:
Rumour I heard from a large airline in the Middle East is they had a blade failure and it may impact ETDO at EIS. Obviously if proves to be true a sensitive subject so I guess they will be doing their very best to resolve it before then through further testing.


That would make it two unconnected issues.
* Blade out issues.
* some problems with the variable stator actuation.

Did the parent engine ever get its blade out test fully done or does the GE90 still run on an FAA waver?
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Eyad89
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 7:23 am

WIederling wrote:

Did the parent engine ever get its blade out test fully done or does the GE90 still run on an FAA waver?



I must ask, how did GE get a waiver for GE90? What was that based on? and why don't other manufacturers waive their own blade tests as well?
 
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KarelXWB
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 8:17 am

lightsaber wrote:
So what is the issue with the GE9X. I have no idea.


The article describes the following:

The GE9X issue is related to the lever arms that actuate the rows of variable stator vanes (VSV) that modulate flow through the 11-stage high-pressure compressor (HPC). “The GE9X team had a test finding in the HPC during a demonstrator engine test late last year,” says the engine-maker. “After analyzing the engine data, the team determined that the lever arms for the VSVs need to be changed.” The company adds that while the configuration will be changed for the production engine, a decision is still pending on whether flight tests can at least get underway with the existing VSV arrangement on the test engine, which was delivered late last year to GE’s test site in Victorville, California.
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zeke
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 8:24 am

This sort of thing is absolutely normal in engine development
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mmo
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 9:40 am

hayzel777 wrote:
Apparently the vanes' design is no good and they needed a design change to it.


You might want to do a little more research. The problem appears to be loads exceeding the design limits for the lever arms for the VSV (Variable Stator Vanes). The lever arms are external to the engine design and requires a mechanical fix (redesign) to the arms.

The issue with the test aircraft's CF6 engine is related to fan case corrosion and limits on the HP turbine airfoils. This was discovered while the aircraft was undergoing a "routing A-Check".
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WIederling
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 3:57 pm

Eyad89 wrote:
WIederling wrote:

Did the parent engine ever get its blade out test fully done or does the GE90 still run on an FAA waver?



I must ask, how did GE get a waiver for GE90? What was that based on? and why don't other manufacturers waive their own blade tests as well?

My ref was this post:
viewtopic.php?t=1382101#p20054915

Some info around that says this is not the case.
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speedbored
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Re: GE9X Minor Design issue: 777X engine

Mon Feb 05, 2018 4:56 pm

lightsaber wrote:
So what is the issue with the GE9X. I have no idea.

Article says:
The GE9X issue is related to the lever arms that actuate the rows of variable stator vanes (VSV) that modulate flow through the 11-stage high-pressure compressor (HPC). “The GE9X team had a test finding in the HPC during a demonstrator engine test late last year,” says the engine-maker. “After analyzing the engine data, the team determined that the lever arms for the VSVs need to be changed.”

They are claiming it shouldn't impact EIS so doesn't sound too significant at the moment.

Have to agree that the CF6 thing sounds like an excuse.

lightsaber wrote:
I refuse to give out e-mail, so I haven't read the full article, but it looks like the engine for the 777X has a delay.

Do what I did - create a free gmail account just for this sort of signing up purpose. Then they can send you as much junk email as they like and you won't have to read a single word of it :).
 
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Revelation
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Re: GE9X Minor Design issue: 777X engine

Tue Oct 09, 2018 4:25 pm

lightsaber wrote:
I refuse to give out e-mail, so I haven't read the full article, but it looks like the engine for the 777X has a delay.

You should consider a 'burner' gmail account since AvWeek's free newsletter/digest emails bring in a lot of content.

For instance http://aviationweek.com/propulsion/ge9x ... tification showed up in my in-box and fully confirmed what was written in this thread about the VSVs above. Also we read:

A big element of GE’s buildup for production readiness on the GE9X is related to the increased use of CMCs. In all, five components are made from ceramics including the first-stage HP turbine shroud, the first- and second-stage HP turbine nozzles and the inner and outer linings of the combustor.
...
Not everything planned to be made from ceramics made its way onto the engine, however. All the CMC parts in the GE9X are static components, but GE closely studied using the material for the second-stage HP turbine blade in what would have been the first application of ceramics in a rotating part in a commercial aircraft engine. “It flunked the requirement check when we launched the product. We were not ready from a TRL and MRL perspective, even though it had good performance, durability and lots of value,” says Ingling.

So it seems we will need to wait for the first use of CMC in a rotating part in a commercial aircraft engine.

The article tells us that although the VSV issue limited the things they could do with the engine,

“the performance at altitude was just what we were looking for,” Ingling says. “It was a great day when we got the data back from it, which confirmed what we were expecting.”

Of course, I have yet to read any similar article about early flight test saying "OMG, we screwed up and are totally missing targets".

It has a lot more info about the reworked flight test schedule (which is said to not impact EIS date) and the role all of the flight test engines will be playing, and now production engines will be made in NC starting in 2019. It also talks about their ability to scale CMC manufacturing in new ways:

The company is close to finalizing the first vertically integrated CMC supply chain in the U.S. and by 2020 aims to be producing up to 20,000 kg (44,000 lb.) per year of CMC prepreg and 10,000 kg per year of silicon carbide fiber.

“What’s unique about what we do is that we are able to do coatings and infiltration technology at scale and at rate,” says Kaufmann. “With the fiber and matrix, we have solved the ability to coat the fiber in large quantities and to put on chemical vapor deposition coatings in a way that allows us to do it at scale. We can do it in a fiber format that can be made into a tape, which can then be laid out. That’s one of the huge technical hurdles we have overcome.”

Another key breakthrough is the ability to infiltrate or cast parts with silicon with very high densities. “One of the challenges is that many are below 90% density, which in a cyclic fatigue environment is a killer,” he adds. “Our densities are much higher and represent a substantial amount of work that has been done in thermal processing,”

Exciting times! :bigthumbsup:
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Re: GE9X Minor Design issue: 777X engine

Tue Oct 09, 2018 5:44 pm

Revelation wrote:
lightsaber wrote:
I refuse to give out e-mail, so I haven't read the full article, but it looks like the engine for the 777X has a delay.

You should consider a 'burner' gmail account since AvWeek's free newsletter/digest emails bring in a lot of content.

For instance http://aviationweek.com/propulsion/ge9x ... tification showed up in my in-box and fully confirmed what was written in this thread about the VSVs above. Also we read:

A big element of GE’s buildup for production readiness on the GE9X is related to the increased use of CMCs. In all, five components are made from ceramics including the first-stage HP turbine shroud, the first- and second-stage HP turbine nozzles and the inner and outer linings of the combustor.
...
Not everything planned to be made from ceramics made its way onto the engine, however. All the CMC parts in the GE9X are static components, but GE closely studied using the material for the second-stage HP turbine blade in what would have been the first application of ceramics in a rotating part in a commercial aircraft engine. “It flunked the requirement check when we launched the product. We were not ready from a TRL and MRL perspective, even though it had good performance, durability and lots of value,” says Ingling.

So it seems we will need to wait for the first use of CMC in a rotating part in a commercial aircraft engine.

The article tells us that although the VSV issue limited the things they could do with the engine,

“the performance at altitude was just what we were looking for,” Ingling says. “It was a great day when we got the data back from it, which confirmed what we were expecting.”

Of course, I have yet to read any similar article about early flight test saying "OMG, we screwed up and are totally missing targets".

It has a lot more info about the reworked flight test schedule (which is said to not impact EIS date) and the role all of the flight test engines will be playing, and now production engines will be made in NC starting in 2019. It also talks about their ability to scale CMC manufacturing in new ways:

The company is close to finalizing the first vertically integrated CMC supply chain in the U.S. and by 2020 aims to be producing up to 20,000 kg (44,000 lb.) per year of CMC prepreg and 10,000 kg per year of silicon carbide fiber.

“What’s unique about what we do is that we are able to do coatings and infiltration technology at scale and at rate,” says Kaufmann. “With the fiber and matrix, we have solved the ability to coat the fiber in large quantities and to put on chemical vapor deposition coatings in a way that allows us to do it at scale. We can do it in a fiber format that can be made into a tape, which can then be laid out. That’s one of the huge technical hurdles we have overcome.”

Another key breakthrough is the ability to infiltrate or cast parts with silicon with very high densities. “One of the challenges is that many are below 90% density, which in a cyclic fatigue environment is a killer,” he adds. “Our densities are much higher and represent a substantial amount of work that has been done in thermal processing,”

Exciting times! :bigthumbsup:

Thank you for the update on CMCs. I had fully expected rotating CMCs. But just the inlet guide vanes alone are a big deal.

The manufacturing to improve fatigue life is going to be key. GE is well ahead on this technology. CMC high turbine components are a game changer. As big a deal as the GTF.
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WIederling
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Re: GE9X Minor Design issue: 777X engine

Wed Oct 10, 2018 12:31 pm

lightsaber wrote:
The manufacturing to improve fatigue life is going to be key. GE is well ahead on this technology. CMC high turbine components are a game changer. As big a deal as the GTF.


entry / first element into the HP turbine is a guide vane set?
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Revelation
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Re: GE9X Minor Design issue: 777X engine

Wed Oct 10, 2018 1:05 pm

WIederling wrote:
lightsaber wrote:
The manufacturing to improve fatigue life is going to be key. GE is well ahead on this technology. CMC high turbine components are a game changer. As big a deal as the GTF.

entry / first element into the HP turbine is a guide vane set?

Following images should help:

Image

Image

Image

Image

Ref: https://gasturbinetutorial.blogspot.com ... ction.html
Wake up to find out that you are the eyes of the world
The heart has it's beaches, it's homeland and thoughts of it's own
Wake now, discover that you are the song that the morning brings
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