As to confidence long term, would it not be better if the failure had a common cause?

As in, "The GEnx has a tendency to come apart, for varied reasons..."

Or, "Common cause, remedied...."

Carry on....

More trouble ahead?

Investigators find cracks in second Dreamliner engine - CNN.com

The CNN story is ambiguous as to whether the second 787/GEnx-1B event is a new failure mode -

But post #8 in this thread allows that it is siimilar (FMS crack) to the first. To date, only the 748/GEnx-2B Shanghai case is different, and I don't think teardown results have yet been released for that case.

Those pesky Mid-Shafts
 

7 Other Mid Shaft failures. Dec 1995 to April 2007.
Notes; Other engine models CF-6s, CF6-50s, CFM56s and CF6-90s.
Only two may be found in NTSB records (Safety Letters, or Accident/Incident database).
Only two (8/18/00 and 12/6/95) had a finding to a cause.
4/1/07. Continental CF6 - 90 series. No Cause. Shop Tear down Report (by QEMY). Source; ASRS report 733184 and SDR # 2007FA0000350 “Upon inspection of the engine, the fan rotated freely, but the LPT did not rotate. BS1 of the engine showed that the HPT was clean, but the LPT was heavily damaged. The engine was shipped to MFG. Initial inspections showed that the fan mid shaft was separated in the axial plane of the HPC S3 disc. The center vent tube was separated in 3 places all aft of FMS separation. An investigation is on going. Shaft Part 1767M75G03." Continental SDR, number and Link > CALA0700137 on 3/20/07. SDR also said investigation by engineering and GE concluded that an omni seal was not installed during engine buildup and that this caused accelerated corrosion of the FMS and subsequent failure. Ed. Note; ASRS Report 733184. No NTSB Accident/Incident rpt --------------------
6/8/06. A-319. CFM56 series. Uncontained Failure. HPT Rear Shaft. No Cause. Source; SDR # 2006FA0000635. “REF: MRD/001/06 - AC suffered an aborted takeoff. Investigation revealed failure and liberation of the HPT rear shaft where a section of material measuring 3.5 inch circumference had liberated around the 3 seal tooth rack. Similar failures have been experienced on engine. Parts are returned to MFG for investigation. Shaft P/N # 9514M71PO4”. Ed Note; No NTSB Accident/Incident Rpt. -------------------------
8/18/00. Carrier UIEA, 747. CF6 -50. Uncontained Failure. Fan Mid Shaft and Stage 4 Disk departed. Cause; air duct. Source; SDR # UIEA0018 . “FLT 7150 - GYE - On takeoff at 400 AGL, Nr 1 engine exploded and had aircraft vibration. Leveled aircraft at 817 feet. Advised tower had an engine fire and declared an emergency. Dumped 30K fuel and returned to GYE. On arrival, determined that Nr 1 engine had an uncontained failure. Analysis of failure indicated airduct failure in area of seventh stiffener. Airduct machined into fan mid-shaft. Fan mid-shaft separated, resulting in uncontained engine failure and stage 4 disk and related hardware departed the engine/aircraft. Duct Part # 9081M40G11”. Ed. Note; No NTSB Accident/Incident Rpt. ---------------------
3/9/98. United DC-10. CF6 - 6. Fan Mid Shaft (FMS) Separated. No Cause. Source; SDR # 98UAL900110 “shut down Nr 3 engine due to aircraft vibration and high temperature indication. Diverted to HNL landed under amber alert. *S/D* the Fan mid-shaft in the engine separated. The primary cause of failure is still under investigation by General Electric”. Ed Note; no further ‘supplemental’ SDR filed. No NTSB Accident/Incident Rpt . ----------------------
10/7/97. Carrier LY2R. 737. CFM56 series. Shutdown On Takeoff. (HPT) Shaft Failed At Seal Teeth. No Cause. Source; SDR # 98ZZZX1899 . “HPT aft shaft failed on takeoff roll at 80 percent N1. HPT aft shaft failed at seal teeth causing extensive damage down stream in the turbine 2nd LPT areas. P/N 9514M71P04.” Ed. Note; No NTSB Accident/Incident Rpt --------------------.
2/22/96. Continental DC-10. CF6 -50. Uncontained failure. Fan Mid Shaft Sheared Off. No Confirmed Cause. Sources; NTSB Safety Letter A-98-125-126, page 4, and SDR # CAL960187 . “A IAH - FLT 0010 - Takeoff was rejected at 100 knots after the Nr 3 engine experienced loss of power. The SDR will remain open for part information pending investigation. Supplement: Preliminary investigation revealed uncontained failure in LPT rotor area. Shop inspection found the fan mid-shaft sheared off. Submitter stated the suspected cause of failure was the HPC rotor air duct failed and rubbed on fan mid-shaft. (x)”. Ed Note; No further ‘supplemental’ SDR and No NTSB Accident/Incident Rpt. -----------------------------
12/6/95. CF6-50. Uncontained Failure. Fan Mid Shaft Failure, rubbing. Cause; Previous Bearing Failure. Sources; NTSB Safety Recommendation Letter A98-125-126. Link > ;http://www.ntsb.gov/recs/letters/1998/A98_125_126.PDF Also a NTSB Accident/Incident Report # NYC96IA036. “The National Transportation Safety Board determines the probable cause(s) of this incident as follows: failure of the number two engine fan mid shaft, due a fatigue fracture caused by a previous bearing failure, and failure of the operator's maintenance personnel to detect the cracks during subsequent inspections”. NTSB Accident/Incident Report. Link > NYC96IA036 Ed. Note; The only NTSB report of a engine bearing Failure. 43 others were SDR Reports.
Source Notes; NTSB Accident/Incident database Link > N T S B - Aviation Accidents - Index of Months search by date.
FAA’s Service Difficulty database and query search; Link > FAA :: SDR Reporting [Service Difficulty Report Query Page] search by SDR # (control number).

As of yesterday, 10-04-12, Reuters is reporting that GE has located the problem that disabled the 2B GEnx on the 747 in Shanghai, Atlas.

It appears the LowPressure Turbine nozzle was installed incorrectly. No damage forward of the nozzle, and the incident seems isolated to this occurrence.

I apologize for not linking the story here, operator malfunction.

GE Engine Failure Caused by Assembly Error
 

By KATE LINEBAUGH - WSJ
General Electric Co. GE +0.86% said the failure of an aircraft engine on a Boeing Co.BA +1.52% 747-8 in Shanghai was caused by an assembly error, adding a second source of concern about the company's newest engine.

GE told aircraft operators to complete a one-time, hour long inspection of its fleet of 120 GEnx engines in the next 90 days. The inspection will check whether a part that directs air into the rotating blades of the (LP) turbine was properly installed.

The initial findings indicate that "a stage-one nozzle may have been improperly assembled and became dislodged," a spokeswoman for the National Transportation Safety Board said. "Efforts are continuing to determine the reason for these observations."

The problem is the second found by GE with the GEnx, which is fitted on Boeing's Dreamliner and 747s and whose design is at the heart of the company's coming generation of aircraft engines. The mishaps are a black eye for the world's largest jet-engine maker at a time when the aircraft market is booming and the battle among engine makers is fierce.

Unless these issues are "resolved relatively soon and decisively, they could cause some problems with customers refusing delivery of aircraft," said William Storey, president of Teal Group, a Fairfax, Va.-based research firm specializing in aerospace and defense...

barit1

"General Electric Co. GE +0.86% said the failure of an aircraft engine on a Boeing Co.BA +1.52% 747-8 in Shanghai was caused by an assembly error, adding a second source of concern about the company's newest engine."

Howdy. This is confusing to me. The impression I have gotten from reading the trades is that the two engines are separate in concern. Now the second problem appears to be piggy backing on the embrittlement problem.

What is your take, barit1?

Lyman,

The B-787 engine problem in Charleston was due to a mid-shaft cracking problem. The B747 engine problem in Shanghai was due to an assembly problem where a nozzle vane became loose during TO. The engines are different in several respects and the problems are different. Only the press assumed the Shanghai incident to be the same as the Charleston incident.

Lyman - see posts #86 and #91.

Two separate problems which arguably are not one-offs.

The GE challenge is to identify the two different suspect populations and recommend inspection procedures to minimize any chance of combinations on the same aircraft.

Working on a level of finding each and every one is fine, but the timing must preclude the higher risk scenario of two of any combination on the same aircraft.

I expect that is what is being worked and all we will see on the sidelines is the effect of the inspections and removals

lomapaseo

Thanks. That makes it quite clear then. I sensed that from some posts I read, it was implied "two different engines" (1B/2B), and that the one inspection exonerated the other fault, by virtue of design differences/type.

So all nx engines are being inspected for both observed failures.

Given that the two GEnx subtypes are more alike than they are different, that is the only sane course of action. :uhoh:

So a forthcoming AD regarding a shaft coupling failure is followed by an in service manufacturing process failure that halts a flight. The one preceeding, the shaft problem, is being remedied with new shafts, and the second with inspections to eliminate possibilities of poor manufacture remaining on wing.

Are we talking about the GE? Or the TRENT?

Eerie...

lomapaseo:
"These things have a way of working themselves out within a month.

Give me a ring if anything New"

willdo

These things have a way of working themselves out within a month.

Give me a ring if anything New

Will these latest engine problems be causing any more delays to deliveries?

I only ask, as one airline I was expecting to have received theirs by now is now looking at mid November at the earliest.

TURIN
 

Which airline was that?

QATAR.

It was due in July.

Turin.
Via the Tuesday Reuters article, the chief executive of Qatar said the airline would not accept any of the sixty 787s ordered until "The engines have been modified".

Qatar, took delivery of its first B787 on Friday.
Will shortly after be flown to Victorville for work on the IFE system, returning for a formal delivery ceremony around 17th or 18th, before the aircraft is flown away to Doha.:ok:

Were the engines refit with the new shafts?

787 Shafts and corrective action
 

Seems to me that given the shafts have individual manufacturing records, and that suspect -1B shafts (or shaft lots) have likely been identified and segregated, that NOT ALL shafts (FMS) are replaced before delivery.

That said, we are reminded that the customer is king, and pressure from the customer could upset this plan and force 100% replacement, even if technically unwarranted.

"We have informed Boeing that we will not take deivery until the 787's have the new modified shaft."

Tuesday, October 2, 2012 Akbar Al-Baker, CEO Qatar AL. (Reuters)

Seems pretty straightforward to me, the client is demanding new shafts. If I buy a new Ferrari, and the crankshaft won't perform, in fact, it fractures on the test drive, I will want a new and different car, not just a replacement crankshaft. The engine would needs be pulled, and all collaterals might be scuffed, or are damaged when the crank lets go.

What about the internals?

Who is the customer, by the way? Al Baker? Qatar? Me and my Family?

Duty of care should be made public, not hushed on the down low. Besides, it is virtually always true that disclosure and honesty work in favor of the principals, in the long run....

I am not privy to word on your street. Can you link to the IFE issue, and an explanation for Al-Baker's original comments?

I would think Boeing SC would be all over this, and not be pre-empted by anonymous website?

It certainly is not my street either, the first link is not working, and the second page is a subscription only glossy.

thanks mike

I know in the CF6-6 and -50 engines LPT Coupling nut was at the end of the LPT ,,,,the hot end of the engine ,,,stays nice and dry , The Genx is at the front of the engine ,its always more cold and moist (visible during ground runs ). This means it cycles cold to ambient numerous times and creates moisture each time. The Genx flight testing was done at Victorville in the Mojave Desert,where its nice and dry, the failure occurred in the South where its wet and humid. If the LPT coupling nut was over torqued, or the threads damaged in handling or manufacturing, and the Anti-cease is now hygroscopic, I suppose this could create accelerated corrosion, but I think it is more likely since the short time on these engines that they were damaged upon assembly. Worst case would be a design flaw of having chosen to put the coupling nut in front ..........I don't know if the GE-90 is designed in this configuration? But I would assume this allows replacing the propulsor easier?

Partially true. More to the point, the CF6 family (-80s too) have splines w/ coupling nut at the AFT AND FWD ends.of the FMS.

Thus the GEnx-1B thread cracking issue seems to be more related to its unique chemistry/metallurgy, and NOT to its non-unique cold-end location. :8

The site of the leading fracture was at the "terminus" of the thread root on the fMS. This suggests a couple things. First, a machining issue, where stress is allowed to focus at the tooling insult. This could also lead to susceptibility to degradation via corrosion, and failure. The problem is that corrosion that happens so quickly seems unusual.

Since all failures happened on the ground, my first guess would have been FOD.

As with the RRTRENT spline AD, the possible link of coupling issues with powerful vibration and consequent failure of downstream internals is present with the GE.

The underlying issue may be a flirtation with minimum materials, both dimensionally, and inadvertently, in spec, and unproven economics.

The 2B is fit on the puffing Boeing, the 1B on the Boeing that has pneumatics independent of bleed air. The 2B is nine inches shorter, and has one less LPT stage, case in point?

Edit to correct, the 2B is the shorter engine...

Also to say that what goes through the engine is not air, but MASS.

4000 pounds of it, each second. That they stay together for the most part is a triumph. Hat's off, to all the engine builders....

And, I think these observations are conjecture without any data to support them, whatsoever.

The fan midshaft cracking and fracturing incidents on the Boeing 787 (GEnx-1B) were traced last month to a new, lead-free coating that allowed the component to corrode rapidly under certain conditions. GE switched to a leaded coating already used on the GE90 to correct the problem.

The problem on the 747-8F (GEnx-2B) has been traced to the Stage 1 LPT nozzle assembly problem which permitted one or more of the nozzle segments to shift aft contacting the Stage 1 LPT blade rotor during the early stage of TO.

The GEnx-1B engine used on the Boeing 787-8/-9 is 184.7" long and consists of 1 Fan, a 4 stage LPC, a 10 stage HPC, a 2 stage HPT, and a 7 stage LPT.

The GEnx-2B engine used on the 747-8F and 747-8 Intercontinental is 169.7" long, and consists of 1 fan, a 3 stage LPC, a 10 stage HPC, a 2 stage HPT, and a 6 stage LPT.

The HPC and HPT are common to both engines. The fan diameter is ~7.0" larger on the GEnx-1B verses the GEnx-2B. On both engines, the fan, LPC and LPT rotate counterclockwise relative to the HPC and HPT.

At the risk of being a pedant, strictly speaking the 787 has no pneumatics (IE The application of pressurized gas to affect mechanical motion).

Only the air conditioning system uses air from electrical compressors.

I think...:O

Except for the engine anti-ice. Which means for the engine: there is a provision to extract hot compressed air from its core.

(Speaking from a total lack of 787 detail knowledge...)

How are wings etc de-iced on the 787? Electrically?

If so, why can't the engine inlet likewise be electrically anti-iced? :confused:

BTW, thinking of the goose/gander differentiation, is the Trent 1000 treated the same? :confused::confused:

I believe so, yes.

Not sure. Perhaps it's because the pipework is very limited, or the response time of hot air versus electric heating, or the temperature itself.

787 the only bleed is a 2 inch duct for the NAI. The wing leading edge slats 2,3,4 5, and 8,9,10,11 are electrically heated. Symmetrical pairs and also symmetrical sections.
As for the NAI it's a lot simpler to run a small length of duct!:8

Thank you, gas path.

Did not know AirFranceIndustrie was heavy into engine maintenance

Air France-KLM Sees Engine MRO Deal with Rolls Royce in 2013 | Fox Business

Forty years ago the ATLAS consortium (AF, LH, IB, Alitalia, and Sabena) pooled resources to maintain early widebody fleets. Most of ATLAS had bought the DC-10-30, although AF did not. Yet the AF shop performed heavy maintenance on the CF6-50 engine for the other consortium members.

Of course a year or two later AF started flying A300s - using the same powerplant package as the DC-10-30.