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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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