Air NZ 787 RR engine issues
Joined: Aug 2005
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From: fairly close to the colonial capitol
tdracer,
I also suspect the alloy being used for the turbine blades may be more prone to corrosion than perhaps other alloys required by other engine manufacturers. In other words, if the coating deteriorates, the bare alloy needs to provide a margin for a period of time in terms of strength and corrosion resistance.
I also suspect the alloy being used for the turbine blades may be more prone to corrosion than perhaps other alloys required by other engine manufacturers. In other words, if the coating deteriorates, the bare alloy needs to provide a margin for a period of time in terms of strength and corrosion resistance.
Doesn't this issue go back a couple of months to some issues with ANA aircraft? I seem to remember RR discovered an issue with premature wear or something and began a programme of engine inspections/replacements. I think a couple of the LHR based VS planes were taken out of circulation for a while recently because of this.
According to RR, the corrosion problem is more likely to appear on long haul flights due to the nature of the corrosion process. A separate issue, involving the IP compressor blades is currently under an EASA mandate review for early inspection to avoid a blade out event, of which three have been reported so far, while RR works on a solution.
Joined: Dec 2010
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From: Middle America
Originally Posted by vapilot2004
I understand the coatings are ceramic with the nickel alloy at the core having a melt point several hundred degrees short of the temps seen in that stage of the engine.
I understand the coatings are ceramic with the nickel alloy at the core having a melt point several hundred degrees short of the temps seen in that stage of the engine.
Most modern nickel-base alloys have a melting point above 900°C. If the temperatures exceed the melting point of the base alloy in the early stage of the LP turbine (IP turbine in RR jargon), the blades need to be air-cooled like what is done in the HP turbine. Certainly ceramic coatings can and do improve the temperature margin between the melting point of the alloy and the actual temperature of the air passing over the ceramic coating. Ceramic coatings are made up generally of four layers of differing materials. Ceramic TBC (thermal barrier coatings) fail through various degradation modes that include mechanical rumpling of the bond coat during thermal cyclic exposure, accelerated oxidation, hot corrosion and molten deposit degradation. There are also issues with oxidation. Sometimes, not well matched thermal expansion coefficients between the coating layers lead to coating cracking and coating failure. Areas of the ceramic TBCs can get stripped off, which reduces the life of the metal drastically, which leads to thermal fatigue and eventual failure.
Joined: Mar 2002
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From: Florida
Mostly agree
but;
taking other's posts into account I'm not sure there is agreement what area of the engine is the one wearing out. Setting aside the original title of the thread, which unfortunately refers to a specific airline's flight. I only offer a general comment on the mysteriously sourced photos above. That damage as seen, appears to be secondary to something coming loose upstream in the turbine. It could very well be in stages that are coated.
As such while the gas temperature may be very high compared to melting points, the metal temperature itself is expected to be much cooler due to cooling air. So the idea of the coating is to provide an erosion barrier between the gas and the susceptible metal underneath the coating.
In this case discussions need to be careful about direct comparisons between engine gas temperatures and bulk metal melting temperatures.
but;
taking other's posts into account I'm not sure there is agreement what area of the engine is the one wearing out. Setting aside the original title of the thread, which unfortunately refers to a specific airline's flight. I only offer a general comment on the mysteriously sourced photos above. That damage as seen, appears to be secondary to something coming loose upstream in the turbine. It could very well be in stages that are coated.
As such while the gas temperature may be very high compared to melting points, the metal temperature itself is expected to be much cooler due to cooling air. So the idea of the coating is to provide an erosion barrier between the gas and the susceptible metal underneath the coating.
In this case discussions need to be careful about direct comparisons between engine gas temperatures and bulk metal melting temperatures.
Joined: Aug 2007
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From: London
EASA EAD 2017-0253-E: ROLLS-ROYCE plc Trent 1000 Engines: Engine Removal / De-Pairing
Looks like a lot of disruption is coming up over the next few weeks?
It is an interesting concept to sell to the public. 'Don't worry about it, we only have one dodgy engine on today's flight so we should get where we're going.'
Looks like a lot of disruption is coming up over the next few weeks?
It is an interesting concept to sell to the public. 'Don't worry about it, we only have one dodgy engine on today's flight so we should get where we're going.'
Joined: Apr 2013
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From: At Home
Not suspended, but self regulated back to 240. Most likely, the only 240 plans will be for IAH and will be operated by the newer 789's that were delivered with the -TEN engines.
Asia and HNL (the bulk of 789 sectors) don't require 240.
777 has taken over EZE for the next few months yes. 240 works, but is not without it's limitations on that route.
Asia and HNL (the bulk of 789 sectors) don't require 240.
777 has taken over EZE for the next few months yes. 240 works, but is not without it's limitations on that route.
Joined: Jan 2008
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From: Herts, UK
Yes.. exactly. Reaching for the limits of cycle efficiency & materials technology. Size plays a factor but generally in turbines and aircraft a positive one efficiency wise.
That said, perhaps what was meant rather than said is that RR are wringing this one out particularly hard.
That said, perhaps what was meant rather than said is that RR are wringing this one out particularly hard.
Joined: Apr 2010
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From: London
All engine manufacturers are pushing the envelope (s)very hard - delays on delivery /problems on new engines from all the major players and SAFFRAN booted off the Falcon due to the impossibility of delivering a working engine.
Joined: Dec 2010
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From: Middle America
HH,
Nothing new in your observation, going way back to the introduction of the 747 by Pan-Am. It's known as progress and as often occurs, "The best laid plans of mice and man often go astray." What is new is the instant news made available by the internet and on-line sites such as this one. Bet you never saw the newly introduced to service Pan-Am 747s parked at JFK with cement blocks on the wings because of lack of engines due to a HPT technical problem.
All engine manufacturers are pushing the envelope (s)very hard - delays on delivery /problems on new engines from all the major players
Nemo Me Impune Lacessit
Joined: Jun 2004
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From: Chabanais, France
consequential losses.
Which are insurable, at a price and with stringent Ts & Cs, depends whether RR bought the option to insure and protect the share price. Not the first time RR have had major engine problems and survived. As soon as RR saw the first engine to be affected one likes to think they will have anticipated and laid plans for what is happening now. Probably impossible to avoid considerable disruption though.
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From: the edge of madness
I wonder if they considered buying GenX engines instead - the pylon / installation is applicable to both types? Presumably, RR could not afford to let them defect and made an offer that Norwegian couldn't refuse . .
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From: Reading, UK
Joined: Apr 2008
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From: London
Joined: Jan 2008
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From: Reading, UK
Joined: Apr 2002
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From: the edge of madness
Though presumably that was done to save on production costs, not necessarily to facilitate an operator retrofitting a different engine.
When Ethiopian took some of the terrible teens, they considered swapping Trents for GenX but decided against it in the end. If the Trent 1000's woes continue, swaps could happen.