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GE issues warning to 777-300ER operators

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posted on May, 16 2013 @ 02:15 PM
GE has issued two Service Bulletins to Boeing 777-300ER operators over the GE90-115B installed on newer aircraft. A six month production run of gearboxes have a material "anomaly" that has led to two engine shutdowns in flight. GE has said that either the gearboxes need to be replaced, or at least one engine replaced with an older engine to ensure that one of the engines has an older gearbox that is not from the suspect batch.

The first incident was an Aeroflot 777-300ER from Moscow to Bangkok on Feb 11th, the second was an Air China flight from Beijing to Paris, that diverted to Stockholm after shutting down the left engine on May 9th.

GE is rushing replacement gearboxes to customers, as well as being in the process of developing an on wing procedure to check the gearbox for gear separation.

The problem is only in 118 gear boxes produced from September 2012 to March 2013. The FAA is expected to issue an airworthiness directive soon.

A group of airlines operating mostly brand new Boeing 777-300ERs powered by General Electric GE90-115Bs are either replacing entire engines or transfer gearboxes on individual units after GE alerted them to the potential for a gear separation.

The engine manufacturer has issued two service bulletins (SBs) to GE90-115B operators after two in-flight shut downs due to gear separation within the Avio-made gearboxes. The first event occurred on Feb. 11 when an Aeroflot 777-300ER shut down an engine enroute to Moscow from Bangkok, and the second took place on May 9, when an Air China flight from Beijing to Paris diverted to Stockholm after the left engine had to be shut down in flight.

Although no specific root cause has yet been identified, GE says a material “anomaly” has been identified during early analysis of the transfer gearboxes concerned.


posted on May, 16 2013 @ 04:02 PM

Originally posted by Zaphod58
...or at least one engine replaced with an older engine to ensure that one of the engines has an older gearbox that is not from the suspect batch.

All things being equal, I would prefer all engines work correctly.

posted on May, 16 2013 @ 04:04 PM
It's a good thing they caught this before it became catastrophic. The FAA is about one of the only government programs I approve of - for the most part.

As far as the SB goes, too bad you have to request permission from GE to view them, and only if you're a customer.

I guess we'll see the AD soon enough, keep an eye out!

posted on May, 16 2013 @ 04:49 PM
reply to post by AnonymousCitizen

So would I, but at $20+ million an engine, the airlines may opt for this route. The 777 is more than capable of flying from take off to landing on one engine fully loaded.

posted on May, 16 2013 @ 06:52 PM
Its going to be either Bush's fault, or the fault of the Sequester.

My guess.

posted on Jul, 16 2013 @ 07:10 AM
A new AD has come out, expanding the suspect population of gearboxes up until June. On July 2nd a Korean Airlines 777-300ER going from Chicago to Incheon had to divert to Anadyr, Russia. A failure of one of the gear boxes is suspected.

Avio suspects that the cracks are related to the heat transfer process in manufacturing. They have since switched to a cold "shot peening" method, that impacts the box with high-velocity shot to deform the metal, making it more resistant to fatigue.

posted on Jul, 26 2013 @ 09:54 AM
The investigation has taken a turn. The FAA has issued an emergency AD to all 777 operators to check the gearbox of the GE90-115B. Until recently, the engine has been incredibly reliable, but recently they have been seeing problems in the gearbox.

It was believed that the problem stemmed from a materials failure and was limited to a small number of gearboxes, manufactured after last September, through about March of this year. GE performed an ECI (Eddy Current Inspection) to check for gear separation within the gearbox. The inspection showed two more cases of cracking, but didn't highlight materials failure as the problem.

GE began looking at the heat transfer process used in manufacturing the gearboxes as a possible cause, and operators were told to change either the gearbox in at least one engine, or one engine itself, to keep from having "twinned" gearboxes on one aircraft. That way if one failed, there was still a separate gearbox operating from a "good" batch.

The investigation was thrown a curveball on July 2nd, when an Incheon bound Korean Airlines 777 was forced to divert to Russia, after a failure that was almost identical to the prior failures on other aircraft. This aircraft was brand new, and the gearbox for both engines had been produced in June of this year, several months after the suspect batch of materials.

The AD orders 20 more 777-300ERs to be "de-twinned" and have at least one gearbox or engine changed with either an earlier produced one of the same type, or a modified gearbox. GE says the suspect gearboxes are down to approximately 29, and should all be out of service by September.

AvWeek Gearbox article

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