KELPkid
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Ntsb Issues Recommendations RE: GEnx Failures

Fri Sep 14, 2012 11:17 pm

So here's the scoop:

http://www.reuters.com/article/2012/...L1E8KEMFZ20120914?type=marketsNews

The NTSB is recommending that the FAA issue an Airworthiness Directive that requires a one time inspection (via an ultrasound test method developed by GE) of all GEnx engines in service. Reportedly, about 50% of them have already received this inspection. They also recommend a recurring inspection at regular intervals of the part implicated in the failures.
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PHX787
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Fri Sep 14, 2012 11:21 pm

(methinks this belongs in tech ops)

What's causing this cracking? Poor construction, or just wear and tear?

If it's the construction I think GE should be liable to replace that part with something more durable. (unless it's something more serious)
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KELPkid
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Fri Sep 14, 2012 11:22 pm

Quoting PHX787 (Reply 1):
If it's the construction I think GE should be liable to replace that part with something more durable. (unless it's something more serious)

According to the article, GE has already addressed the issue with a change to their manufacturing process, but this obviously won't cover engines already in service  
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atcsundevil
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Sat Sep 15, 2012 3:38 am

Quoting PHX787 (Reply 1):
If it's the construction I think GE should be liable to replace that part with something more durable. (unless it's something more serious)

There's no need to replace something that's doing its job. I'm not familiar with this particular situation, but generally when a manufacturer issues a service bulletin recommending certain or more frequent inspections (sometimes followed up with an AD), it doesn't mean the component is faulty...they're just asking the mechanics to check more frequently that the component is working properly. If they've introduced a fix on newer models but the component is still doing its job and doesn't pose a safety risk on the older models, there's no justification for the expense and down-time to replace the component. If the component needed replacement, the company would have indicated as such to avoid potential litigation and the FAA would issue an AD to replace the part either immediately or within a timeline.
 
mffoda
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Sat Sep 15, 2012 3:45 am

The other thread has this info already... Do we really need this thread also?


So here is the latest form NTSB on FG on this matter.

http://www.flightglobal.com/news/art...enx-powered-787-and-747-8s-376525/


"The recommendations issued by the National Transportation Safety Board (NTSB) offer the clearest explanation yet for the rash of zero- or low-time GEnx engine failures since 28 July.

The NTSB letter sent to the Federal Aviation Administration also reveals that an analysis of the fan midshaft fractures do not point to metal fatigue as a likely cause. The fan midshaft connects the low pressure turbine to the fan and booster stages at the forward end of the engine.

Instead, the cracks in the critical engine component are "typical of environmentally assisted cracking of certain high strength alloys such as that used on the GEnx [fan midshaft]", the NTSB letter says. The NTSB is continuing to investigate what is triggering the environmentally assisted cracking. According to GE, such metals crack as a result of galvanic corrosion caused by a moist environment with the presence of hydrogen.

A potential trigger of the galvanic corrision could have been revealed earlier this week. In a statement issued by GE on 11 September, the company said it has changed the coating process for the fan midshaft on the production line as a result of the engine failures. GE says today that the new coating process changes the dry film applied to the midshaft, and replaces the lubricant used when a retaining nut is clamped to the midshaft.

The NTSB's letter to the FAA indicates all three engine failures discovered to date could be linked to the same cause"
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n737aa
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Tue Sep 18, 2012 1:29 pm

Quoting atcsundevil (Reply 3):
There's no need to replace something that's doing its job. I'm not familiar with this particular situation, but generally when a manufacturer issues a service bulletin recommending certain or more frequent inspections (sometimes followed up with an AD), it doesn't mean the component is faulty...they're just asking the mechanics to check more frequently that the component is working properly. If they've introduced a fix on newer models but the component is still doing its job and doesn't pose a safety risk on the older models, there's no justification for the expense and down-time to replace the component. If the component needed replacement, the company would have indicated as such to avoid potential litigation and the FAA would issue an AD to replace the part either immediately or within a timeline.

AD's are safety related....so your theory is wrong. Typically on a new product such as this the first release of the AD will include inspection criteria to allow OEM time to develop a termination procedure which usually involves replacement of the part.

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mffoda
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Wed Sep 19, 2012 9:12 pm

Here's the latest form Reuters on the FAA's position...


"FAA won't issue emergency directive on Boeing jets, GE engines

WASHINGTON, Sept 19 | Thu Sep 20, 2012 12:57am IST
(Reuters) - The U.S. Federal Aviation Administration said Wednesday it would stop short of issuing an emergency directive on recently identified problems in General Electric engines on a pair of Boeing Co jet models, sticking instead to more routine safety notices.

An emergency directive could have meant temporary groundings of the GE-powered Boeing 787 and 747-8 jets, for instance, or other significant limits on fleet operations that now may be less likely."


http://in.reuters.com/article/2012/0...oeing-ge-faa-idINL1E8KJBXS20120919
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135mech
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Thu Sep 20, 2012 5:51 pm

Quoting mffoda (Reply 4):
The other thread has this info already... Do we really need this thread also?

What other thread? Airliners.net? Or the flightglobal link? If there is an a.net one, that you know of, post a link.

[Edited 2012-09-20 10:52:38]
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Stitch
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Thu Sep 20, 2012 6:43 pm

Quoting 135mech (Reply 7):
What other thread? Airliners.net? Or the flightglobal link? If there is an a.net one, that you know of, post a link.
747-8 Uncontained Engine Failure? (by tp1040 Sep 13 2012 in Civil Aviation)

and

Official 747-8 Flight Tracking & Production Part 9 (by wilco737 Jun 27 2012 in Civil Aviation)
 
KELPkid
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Thu Sep 20, 2012 7:42 pm

Quoting mffoda (Reply 4):
The other thread has this info already... Do we really need this thread also?

I thought I would open it so that we could talk about the GEnx problems, apart from the 787 and 747-8 airframes. Otherwise, you have to be both a 787 and a 747-8 fanatic to keep abreast of the issue  
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135mech
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RE: Ntsb Issues Recommendations RE: GEnx Failures

Fri Sep 21, 2012 4:58 pm

Quoting Stitch (Reply 8):
Quoting 135mech (Reply 7):
What other thread? Airliners.net? Or the flightglobal link? If there is an a.net one, that you know of, post a link.
747-8 Uncontained Engine Failure? (by tp1040 Sep 13 2012 in Civil Aviation)

and

Official 747-8 Flight Tracking & Production Part 9 (by wilco737 Jun 27 2012 in Civil Aviation)

Great, thanks! I wasn't going to assume which he meant, since there wasn't a link attached at the time.

 
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