Air NZ 787 RR engine issues
 

My national carrier - one of two engine failures in as many days occurred half an hour into an Auckland-Tokyo flight and was described as "the plane starts shaking and making weird noises and the power goes off a bit and we have to turn around". (edit - a known problem so you guys probably already read/discussed it : "Rolls-Royce told investors in August that 400 to 500 Trent 1000 engines were affected by issues with components wearing out earlier than expected") ;

Air New Zealand Dreamliner engine problems cause cancellations - NZ Herald
Air New Zealand says some Boeing 787 Dreamliner flights will have to be cancelled due to problems with the Rolls-Royce engine.
The airline has notified the stock exchange that there will be limited international flight cancellations and delays each day over the coming weeks following problems with the aircraft engines.
Rolls-Royce has informed Air New Zealand that some of its engines on the Boeing 787-9 fleet will require maintenance sooner than previously advised and that it does not have any spare engines available while that maintenance work is undertaken.
A flight to Japan had to turn back on Tuesday and yesterday a flight from Auckland to Buenos Aires had to return to Auckland International Airport.

https://www.airlineratings.com/news/...engine-issues/
Rolls Royce is facing turbulence over 787 engine issues which have left airlines short of spare engines.
Air New Zealand has been forced to ground three of its 787s due to a worldwide shortage of Rolls Royce Trent 1000 engines.
The grounding comes after the airline had two engine events forcing turnbacks over the past two days where the engines shed turbine blades.

Two engine failures in two days on new aircraft certainly gets your attention. If true they shed fan blades and with routings like Auckland Buenos Aires on a twinjet I would be a bit nervous if I was on this fleet. At least in the very early days on the 747 when there were similar failures levels, the aircraft had four engines. The years of safe twin operation (777 etc.) with mature technology have maybe lulled us into a false mindset when considering operations with these new engines.

Given the specifics of the thread is it worth pointing out that it's not just Air NZ having engine "issues" on the 787?

Same issues at Virgin Atlantic. As much as I love the Rolls Royce brand, they're certainly having a tough time of it these days. Perhaps so desperate to keep innovating that they're perhaps developing faster than the materials/electronics etc will allow for?

Could also be a usage issue with harder use than initially expected, thus lowering time on wing.

At any rate this part is technical and may not fit the general discussion on the logistics of dealing with the problem today.

I don't think ANZ would use harder than expected. Almost every flight is long so fewer cycles with the highest loading.

Yikes.


https://www.stuff.co.nz/travel/trave...ged-787-engine


https://resources.stuff.co.nz/conten...2680460416.jpg`
https://static3.stuff.co.nz/rsz-np4d...a-249706b6.jpg


https://static3.stuff.co.nz/rsz-vydd...m-9e466080.jpg

Nice picture of NOT the (either) aircraft in question, but good for shock value....

I was going to say, that would never have got in the air, the walk around check alone would have seen that grounded. Is it volcanic ash damage?

There is a difference between shedding turbine blades verses shedding fan blades and where each are located in the engine. Although undesirable, the turbine blades went out the tailpipe as what they are designed to do...

The pics are showing the back stages of the turbine and blades chewed away from large amounts of forward blades migrating downstream.

What the eye sees is secondary $$$ The damage stems from further forward events.

The major issue is response to the logistical problem of swapping out engines in a fleet.

I find it surprising RR apparently don't have any spare engines...

They've run out.

This issue is a lot more widespread than has been reported. When the cracking was first discovered, RR went around to operators to do inspections. I can't recall the exact numbers, but I believe something like half our engines had to be replaced.

With more engines cracking (worldwide), some being original while others being the replacements, RR is up to their necks in it. :mad:

And the airlines. If it keeps happening would the authorities have something to say about continued ETOPS operations with this sort of failure rate? How/ what/ where will 787 dependent airlines like ANZ find replacement aircraft?

The shutdown rate is tracked pretty much continuously (typically as a 12 month rolling average), if the fleet average goes over .02/1000 (one shutdown per 50,000 engine flight hours) the Feds will likely pull 180 minute ETOPS. That's all codified in the ETOPS rules (the rate for 120 minute and 90 minute ETOPS is allowed to be higher, so they wouldn't necessarily pull ETOPS entirely, just 180 (or longer). Most 180 minute routes can be flown at 120 minutes - but with less optimal routing (the main exception is between the North America and Hawaii - there is literally nothing in between so you need 180).
Individual operators will have different ETOPS shutdown requirements that they've negotiated with their regulatory authorities. For example on smaller fleets a single shutdown can put them over the .02 limit - so they have different requirements such as demonstrating they've taken corrective action to prevent another shutdown due to the same cause.
However before you get too excited, the Rolls 787 fleet is accumulating ~180,000-200,000 hours per month, so they can have several shutdowns per month without exceeding .02.
All that being said, if ANZ had two Trent 1000 shutdowns in as many days, they're going to have some serious explaining to do to retain their 180 ETOPS.

td, especially considering ANZ routes, crossing the Pacific, NZ to North America. I wonder how many 180 minute sectors there are between NZ and the US?
Hope it all works out soon...

There is also 207 minute ETOPS which I believe we use here at EK for the 777! I'm not 100% sure as I'm happy to have four engines running on my 'ship!:ok:

All North American routes from NZ can be done on 180 minute EDTO, you just lose flexibility on routing as after the Pacific Islands there’s only HNL/ITO for coverage. But NA is 777 territory anyway.

IAH would be problematic as the routing would be too far north, but not impossible. EZE is the real issue as routing that far North would simply not be economically viable.

If the 787 gets chopped back to 180EDTO (or less) then I suspect the company will simply shift some 777’s off Asian or HNL routes to pickup IAH/EZE.

So the real issue will be around capacity while Aircraft are grounded rather than EDTO. 240 EDTO is often used for route flexibility across the pacific and I think our max is 330 for EZE. Both of which the 777’s have approval for.

When you have a common cause failure condition, ETOPS assumptions are no longer valid. Instead you work with the inspection results to look at probabilities of common cause adding to independent cause assessments.

Mate’s wife was on a VS 787 which returned to HKG 4 hours after departure, enroute LHR, a couple of nights ago. Was this an engine problem?

HKG return, nope nothing to do with RR on that one, other tech issue unrelated

Earlier this week VS had 2 787s parked up outside their LHR hangar. One with no engines and the other with just one. I assume they are getting sufficiently compensated by RR.

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.

Just to be clear, the .02 shutdown rate is for 180 minute ETOPS - longer ETOPS have correspondingly better shutdown rate requirements. However 180 is important because as I mentioned earlier 180 ETOPS will get you anywhere in the world (although may require less than optimal routing).
No first hand knowledge here but I suspect Kelvin is right and this is the same issue that ANA had. As I understood it - the ANA issue was related to corrosion of the turbine blade. At the high temperatures that turbines operate at, many materials corrode that don't corrode at lower temps - and some of the contaminates and impurities in the air and fuel act as catalysts at high temperatures.
The engine companies try to prevent this with various coatings - I suspect whatever coatings Rolls is using on the Trent 1000 are not working as well as they'd planned...

I think I have said this before but is it possible that the industry has gone a step too far with respect to technology and big airframes/powerplants?

Chris, that's a rather open ended and imprecise question. What do you mean by a "step too far" given the size and power of, for example, the engines on the A380.

I am very interested in these recent reliability events in terms of terms of ETOPS certification process. I'm wondering if a crack (pun not intended) has been found in the certification methodology that has been implemented.

To obtain ETOPS certification, a new model aircraft must conduct a mandated number of hours of operation of the engine type without shutdown required, during the certification period. However, no consideration is given or mandated based on engine wear (number of hours of operation) vs probability of failure.

To maintain a specific ETOPS certification, i.e. ETOPS 75-370, requires that the service history of aircraft using the engine type demonstrate an IFSD (in flight shut down) rate due of less than the specific rate: e.g. 0.01% per 1000 hours for ETOPS 180.

Herein lies the problem. The IFSD rate is averaged across all engines of the certified type, regardless of operational hours. It does not take in the scenario where newer engines are extremely reliable and older engines have a dramatic drop in the reliability rate.

If separate samples were taken by say every 1000 hours of engine life, with the ETOPS rating concurrent with the average IFSD within each 1000 hour period, then I would feel comfortable, but this isn't the methodology used. The high reliability of newer engines (higher at the moment for the B787 as a newer model) can mask the effective unreliability of high operational hour engines.

ETOPS/EDTO certification is part of the equation, but an Airlines approval comes from the regulator.

Regardless of what becomes of the 789's certification, individual regulators might start knocking them back to 180 or less until the Engine issues are resolved.

Yes, it's a 330 min EDTO approval on the B 789. I'm sure the necessary internal and regulatory risk assessments have taken place with prudent outcomes.

Your presumptions are not valid.

Overall (millions of hours) there is such a thing as a bath tub rate high during the learning process of what's near perfect and what doesn't work as expected. These kind of problems get high attention and only after enough hours are ETOPs considered. Then there is the mature rate where wear-out rates are kept track of in scheduled maintenance. In the end the rate often goes up when the product line moves to third tier operators with less diligence.

Meanwhile as I said in my earlier post, this problem, as described so far, is a common cause risk aggravated by a much faster and less defined wear-out rate that has little bearing on the ETOPS data assumptions. As such, day to day inspection results predict the liklihood of any two engines on the same aircraft failing in the same flight.

The fleet mix needs to address this by combinations of engines in and out of the new and changing maintenance schedule. Hence the available engine resource problem until enough "fixed" engines are available to match route structure.

ETOPs is not a protector when you are dealing with dual engine common cause failures since it only assesses the very small probabilities of independent failures

We used to plan to avoid engines on a twin being of similar life since O/H; of course this did incur extra non essential engine changes, hence costs, I wonder if this is still a practice?

Disagree. Auckland-Buenos Aires would not be practical. I think you'd struggle with Perth-Joberg too, for example.

Only one of the two events was a shutdown in terms of EDTO stats.

It's more the pushing of the limits of efficiency.

Hence the difference between impractical and impossible. With (only) 180 minute ETOPS, those routes are impractical. With less than 180 minute ETOPS those routes are impossible...

Yea, assuming all alternates are available, 240 will get you reasonably direct routing between AKL and EZE. 180 will require a dog leg to the North to keep range on the Islands (NCRG/NTAA) before SCIP.

Beyond 240 is good for more southerly routing if the winds are favorable or an Alternate isn't available.

More like have we surpassed practical limits in terms of thrust and airframe design.

Chris2303 mentioned:

No, that stage was reached in 1943 as reported here:

https://en.wikipedia.org/wiki/Junkers_Jumo_004

Jumo -:- thrust -:- weight
109-004B -:- 8.83 kN (1,984 lbf) -:- 745 kg (1,642 lb) 8,700 rpm


https://en.wikipedia.org/wiki/Willia...Specifications
Dry weight: less than 300 lb (140 kg)
Maximum thrust: max takeoff thrust 1500 lbf

Testimonials - Company - Williams International
The Williams FJ44-3AP engines ... and 5,000 hours between overhauls.

Thank god we realised when to stop in 1943 or goodness knows what might have happened?

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.

Not sure about GE having fewer problems than RR. Icing problems in the descent.....high vibration on start etc. That said the oil problems which have always haunted the Trent and its predecessor seem to be rearing their head again.

They aren't that powerful. 747 had 60,000 lbs out of various engines...the 380 max is 72k.