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na
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77W: Severe GE-engine Problems

Thu May 16, 2013 10:44 am

Several German newspapers report that there are problems with the GE-engines on the 777-300ER and that clients have been informed after two recent engine failures. 26 77Ws have been called in for inspection and repair. Seems to be that the latest built are affected as also newbuilds not yet delivered are mentioned.

Article, link to one of the most respected German newspapers:
http://www.faz.net/aktuell/wirtschaf...in-boeing-flugzeugen-12184731.html
 
andrej
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 11:39 am

-> According to reports, problem is with the 'transfer gear boxes' (transfers power from the engine to fuel pumps) made by Avio SpA between Sept. 2012 and March 2013. The problem is 'an anomaly in the material that caused gears to separate'.

-> GE and Avio advised airlines to inspect or replace the gear boxes in at least one engine by September 2013.

EDIT: Additional information.

-> Spare parts are provided by GE.
-> Failure can cause IFS.

[Edited 2013-05-16 04:51:56]

[Edited 2013-05-16 04:52:18]
 
na
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 11:46 am

Quoting andrej (Reply 1):
-> GE and Avio advised airlines to inspect or replace the gear boxes in at least one engine by September 2013.

The FAZ article speaks of 26 + 44 aircraft, not just one engine! Several airlines have been called for inspections/replacements.
 
andrej
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 11:48 am

Quoting na (Reply 2):
The FAZ article speaks of 26 + 44 aircraft, not just one engine! Several airlines have been called for inspections/replacements.

That is true, but recommendation (as I understand from reports) is to check/replace at least one engine (of the affected planes).  

[Edited 2013-05-16 04:49:52]
 
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Revelation
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 12:10 pm

The headline is a bit sensational, IMHO.

I prefer AvWeek: 777 operators take action over GE90-115B gearbox issues

In short, yes, problems have been found and engines and/or gearboxes are being swapped to remove a questionable batch of gearboxes from service.

Quote:

Despite the large number of gearboxes in the suspect batch the actual number of aircraft impacted remains relatively small because of the distribution of the units among the engine fleet. Some 32 of the gearboxes are either on engines that are for spares or which have yet to be delivered. Aside from 26 of the engines that are subject to immediate removal or gearbox exchange, the remaining 60 engines include 34 ‘singles’ that are paired with engines not affected by the SB. The balance of 26 engines are those paired with the engines now being either removed or being fitted with replacement gearboxes. These will be subjected to subsequent on-wing ECI checks.

So it's a big hassle for everyone involved, but not sure I'd go to 'severe'.

The industry has been through similar things before, such as Rolls-Royce, Boeing Scramble To Replace Gearboxes On ANA's 787s

Granted that's a newer engine on a much smaller fleet of planes, but the point is that the industry knows this particular fire drill.
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Tristarsteve
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 12:15 pm

Quoting andrej (Reply 1):
-> Failure can cause IFS.

There is an Air China in the hangar at ARN having an engine change after an IFSD and diversion due to transfer gearbox failure.
 
mjoelnir
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 12:17 pm

Quoting Revelation (Reply 4):
The industry has been through similar things before, such as Rolls-Royce, Boeing Scramble To Replace Gearboxes On ANA's 787s

But in those cases the talk was also about severe.
If you have to swap, because you can not trust that particular engine not to fail, than I would call it severe.

But GE seems to have it well in hand, knows the fault and reacts fast and professional.
In the end all those gearboxes have to be exchanged.
 
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prchan
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 1:01 pm

Does someone knows which 26 frames/operators are on the repair list?
 
mjoelnir
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 1:03 pm

Quoting prchan (Reply 7):
Does someone knows which 26 frames/operators are on the repair list?

Go through a list of the last 26 deliveries of new frames, that are the ones with two engines with that gearbox.
 
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747classic
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 1:14 pm

Remarkable that 777 aircraft with two suspected engines are allowed to be operated for 5 more days.
What's the ETOPS status with one suspected engine ?
Operating a twin over the ocean, you're always one engine failure from a total emergency.
 
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lightsaber
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 2:18 pm

Quoting andrej (Reply 1):
-> According to reports, problem is with the 'transfer gear boxes' (transfers power from the engine to fuel pumps) made by Avio SpA between Sept. 2012 and March 2013. The problem is 'an anomaly in the material that caused gears to separate'.

Why a bad mistake, these happen.

As far as engine troubles go, having the issue in an LRU is a blessing...

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BoeingVista
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 2:43 pm

Quoting mjoelnir (Reply 8):
Go through a list of the last 26 deliveries of new frames, that are the ones with two engines with that gearbox.

Ali Baker was whinging about 777 engines a last week, telling GE to fix an unspecified problem, seems that Qatar owns 3 of the last 26 deliveries.
BV
 
aacun
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 3:03 pm

At AA, 4 of the 6 airplanes need to have changes done and will take place by sun May 19 at DFW and JFK with no customer impact expected.
 
ozark1
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RE: 77W: Severe GE-engine Problems

Thu May 16, 2013 11:41 pm

Well, AA Flight 50, DFW-LHR, is currently estimated to leave 3 hours late this evening. Flight info remarks in SABRE say "coming from hangar". So not sure if this has anything to do with it or not.
 
fishmeal
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RE: 77W: Severe GE-engine Problems

Fri May 17, 2013 1:48 am

AA 50 Just took off at 8:45.
 
SPREE34
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RE: 77W: Severe GE-engine Problems

Fri May 17, 2013 2:29 am

Quoting andrej (Reply 3):
is to check/replace at least one engine (of the affected planes).  

Negative. Replace at least one gearbox.
I don't understand everything I don't know about this.
 
cornutt
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RE: 77W: Severe GE-engine Problems

Fri May 17, 2013 4:20 am

Quoting 747classic (Reply 9):
Remarkable that 777 aircraft with two suspected engines are allowed to be operated for 5 more days.

Probably based on the estimated mean time to failure, and from that calculating the probability of failure in the next 50 or so hours.
 
andrej
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RE: 77W: Severe GE-engine Problems

Fri May 17, 2013 5:05 am

Quoting SPREE34 (Reply 15):
Negative. Replace at least one gearbox.

I stand corrected. And it makes economic sense.  
 
AirbusA6
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RE: 77W: Severe GE-engine Problems

Fri May 17, 2013 8:50 am

After a period when they were curiously owned by a British private equity entity, Avio are now owned by GE I believe, whereas the RR Trent gearbox problem was caused by a subsidiary of UTC (owners of rival PW!)
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ferpe
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RE: 77W: Severe GE-engine Problems

Sat May 18, 2013 4:50 am

Quoting AirbusA6 (Reply 18):
After a period when they were curiously owned by a British private equity entity, Avio are now owned by GE I believe, whereas the RR Trent gearbox problem was caused by a subsidiary of UTC (owners of rival PW!)

There is a huge difference between the RR and GE issue. For the Trent it was a coating which could long term cause a transfer shaft to rust that could long term damage the transfer gearbox, not specified what and how severe. But it was a precautionary action after RR/UTC discovered a sub-supplier had changed the shaft coating process which no longer guaranteed that the transfer shaft did not rust over time (rust means the surface of the shaft gets scruffy, it does not affect the strength of the shaft).

In the GE/AVIO case we are talking about an acute sever failure probability (a tranfer gear severing) which actually happened on 2 in service engines within close proximity time wise where the aircraft 1. loose all auxiliary drive on the engine and 2. needs to shut down the egine and 3. it could affect both engine on the same frame if you are unlucky as the faulty shafts affected a ceratin delivery batch and both engines on newly delivered frames belongs to this batch. Now imagine getting both shaft gears severed when flying over the ocean, a bit iffy  Wow! (edit: it would be iffy if over land as well, glide landing a 777-300ER would not be normal airmanship   )

So very different things and the GE case warrant immediately securing that at least one engine does not belong to the affected engines.

[Edited 2013-05-17 21:58:47]
Non French in France
 
goldenstate
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RE: 77W: Severe GE-engine Problems

Sat May 18, 2013 5:30 am

This is in addition to the LPT stage 6 blade failures that are also impacting global GE90-110/115 reliability. Some operators are seeing their entire fleet of GE90s driven off-wing for LPT swaps. Needless to say, they are not happy.
 
sweair
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RE: 77W: Severe GE-engine Problems

Sat May 18, 2013 6:43 am

Another example of having a diverse fleet being good, A+RR and B+GE, the safest way really. On this site many love a sole source OEM on both airframe and engines, but that does come with risk.

The airlines going for the A350 would be wise to hang on to their older 777s for a while before the A350 is mature.
 
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jetmech
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RE: 77W: Severe GE-engine Problems

Sat May 18, 2013 8:16 am

Quoting Tristarsteve (Reply 5):
IFSD and diversion due to transfer gearbox failure.
Quoting ferpe (Reply 19):
needs to shut down the egine and 3

Would I be correct in assuming that an inability to transmit power to the external gearbox of a GE-90 automatically results in an engine shutdown?

As I understand it, the engine driven fuel pump (EDFP) can suction bypass the boost pumps in the fuel tanks, however, the boost pumps cannot force fuel past a stopped EDFP as the high pressure stage of an EDFP is usually configured as a positive displacement arrangement.

Even if there is a bypass around the EDFP, the boost pumps would not put out anywhere near the required pressure demanded by the spray nozzles.

Regards, JetMech

[Edited 2013-05-18 01:18:03]
JetMech split the back of his pants. He can feel the wind in his hair :shock: .
 
JoeCanuck
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RE: 77W: Severe GE-engine Problems

Sat May 18, 2013 9:16 am

Quoting sweair (Reply 21):
The airlines going for the A350 would be wise to hang on to their older 777s for a while before the A350 is mature.

Ironically, this is a new problem and has come despite years of testing. Somebody made an oops in the middle of a production run.
What the...?
 
Tristarsteve
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RE: 77W: Severe GE-engine Problems

Sun May 19, 2013 9:42 am

Quoting jetmech (Reply 22):
Would I be correct in assuming that an inability to transmit power to the external gearbox of a GE-90 automatically results in an engine shutdown?

If the external gearbiox loses its drive, the engine stops.
The hyd pumps stop, the fuel pump stops.

Quoting jetmech (Reply 22):
the boost pumps would not put out anywhere near the required pressure demanded by the spray nozzles.

Boost pumps are around 30 psi, the engine fuel pump is 1800 psi.
 
SASDC8
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RE: 77W: Severe GE-engine Problems

Sun May 19, 2013 9:54 am

So if I understand this correctly the engine will stop and can't be restarted if the gearbox fails? How can this not impact ETOPS for the afflicted 77Ws?
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Aesma
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RE: 77W: Severe GE-engine Problems

Sun May 19, 2013 7:52 pm

ETOPS is up to regulators, and the regulators have not yet said anything, although I'm sure that's because they see that Boeing/GE are scrambling to replace the affected parts. Once there is no affected engine being used then there is no need to review the ratings.
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Unflug
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RE: 77W: Severe GE-engine Problems

Mon May 20, 2013 3:59 am

Quoting Revelation (Reply 4):
The headline is a bit sensational, IMHO.

True.

Quoting na (Thread starter):
Article, link to one of the most respected German newspapers:

Not really. Very conservative paper with lots of misinformation. Well respected with those who read nothing else.
 
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jetmech
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RE: 77W: Severe GE-engine Problems

Mon May 20, 2013 2:08 pm

Quoting Tristarsteve (Reply 24):
If the external gearbiox loses its drive, the engine stops.
The hyd pumps stop, the fuel pump stops.

A similar setup to many other commercial types.

Quoting Tristarsteve (Reply 24):
Boost pumps are around 30 psi, the engine fuel pump is 1800 psi.

Perhaps they could fit a positive displacement backup pump on the engine or in the tanks? It could be driven electrically, pneumatically or hydraulically   .

Regards, JetMech

[Edited 2013-05-20 07:14:57]
JetMech split the back of his pants. He can feel the wind in his hair :shock: .

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