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.