It depends on what and where the actual damage is. It's not going to suddenly become cheap, but if it's fairly minor damage that's easy to replace,
but not something you can fly with long term, it'll be cheaper.
a reply to: Zaphod58
It begs the question, why did they continue flying with high vibes? They must have been off the scale to have caused serious damage,and not one but
two airframes? There are several SE Asian airlines who have been notorious for continuing to fly with vibration levels that other airlines would have
grounded. Maybe LATAM should be footing some of that bill too?
Rolls Royce is warning of increased disruptions due to required inspections of the Trent 1000 with the Package C compressor. The Package B engines
aren't affected, but there are 380 Package C engines in service.
Wow, the new AD that was released on the 16th has a lot more detail. The IPC seal, stage 1 and 2 blades, and dovetail posts that attach the blades to
the IPC shaft are suffering from resonance vibrations under specific thrust and temperature conditions that increase fatigue damage. It's believed
that the resonance is caused by interaction between the stage 2 blades, and the fan wake. They're now calling for inspections of all engines,
initially after 2,000 cycles, and then every 200-300 cycles after that point.
Thats a potentially complex problem to solve. They either need to stiffen the IPC blades, change materials or treatment processes, redesign them,
change the blade root, or change the fan blade design. Failing that the only other avenue I can see is maybe software changes to change the engine
scheduling, fan speed etc at certain flight phases. Possibly a combination of all of these things too. I wouldn't be surprised if the 1 year delay
extends beyond that due to the complexity of this kind of interaction. Meanwhile this is having quite a severe impact on operators like Air NZ, with
1960's style fuel stops required for routes that haven't seen that kind of need in
decades.Air NZ 787 ETOPS FG article
So the fatigue isn't a result of larger diameter and then the increased centrifugal force just plain outwards tryin to go near super sonic....?I'm
just curious, seems some turbines push a little into supersonic
a reply to: GBP/JPY
No the problem is a combination of larger diameter and corresponding centrifugal forces coupled with greatly increased Engine Pressure Ratio's (EPR)
and increased thrust. There really isn't any increase in either RPM or a trend towards supersonic tip speeds, that would just increase noise greatly
and increase fuel burn. If you take a look at the difference in say the 737-100 of 1967 fitted with a P&W JT-8D's with a 737-8 MAX from 2018 powered
by CFM LEAP 1-B you see a roughly doubling of thrust from around 14/16,000lbs to over 29,000lbs. Even more importantly we see pressure ratios increase
from well below 20:1 in the JT-8 through the high 20:1's to low 30:1's in the later CFM-56-5/7's through to 40:1 or up to 50:1 at top of climb in the
LEAP-1B. However there hasn't been a corresponding increase in weight, even though it has gone up. Despite materials advances, something has to give.
In some engines there is an even greater leap in these numbers so its little surprise that we are seeing these failures.
And the hits just keep coming. There's a little confusion about this one, but it appears that Virgin Atlantic at least has been told their ETOPS
flights are reduced to ETOPS 60, meaning they can be no farther than 60 minutes from a diversion airport.
Meanwhile Rolls Royce has said they're working hard to fix the problem, but that fix might not be fully implemented until 2022.
a reply to: Zaphod58
What?.... 60 mins ETOPS, f**k! That is going to severely hamper a lot of Trent 78 operators if it becomes widespread. It could also potentially
bankrupt RR. I'm betting my previous assessment that its a much more complex problem than first thought is the case.
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