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Sokes
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Re: Potential that A220 is grounded following new engine issues ?

Thu Sep 19, 2019 5:14 pm

Nicoeddf wrote:
ETOPS reduction or withdrawal? Sure, is in the cards. Grounding? Not really, until a potential failure mode is identified, that could lead to a same time IFSD event of both engines.


I agree.
If engine makers face the risk that plane types with new engines are withdrawn from service for occasional contained engine failures, there won't be any more new engine technology. One can't avoid real live testing as there may always be wrong assumptions in the testing procedure.
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SteelChair
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Re: Rumour: A220 GTF IFSD

Thu Sep 19, 2019 5:48 pm

The silence from PW and the lack of investigative journalism in the aviation sector isn't helping things.

Contrast the current lack of information with the IFSD information that Boeing promulgated with regularity in the first 20 years of ETOPS
 
Etheereal
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Re: Potential that A220 is grounded following new engine issues ?

Thu Sep 19, 2019 6:04 pm

Nicoeddf wrote:
IFSDs don't kill people.


[citation needed]
 
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zeke
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Re: Potential that A220 is grounded following new engine issues ?

Thu Sep 19, 2019 6:27 pm

Cubsrule wrote:
But the A220 has only one engine type, no? So here, grounding the engine versus grounding the airframe is a distinction without a difference.


If there is an engine issue that warrants an AD, the AD will be issued against the engine not the airframe.

You should have seen how unreliable large piston engines were.
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litz
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Re: Potential that A220 is grounded following new engine issues ?

Thu Sep 19, 2019 6:50 pm

zeke wrote:
Cubsrule wrote:
But the A220 has only one engine type, no? So here, grounding the engine versus grounding the airframe is a distinction without a difference.


If there is an engine issue that warrants an AD, the AD will be issued against the engine not the airframe.

You should have seen how unreliable large piston engines were.


Or early jet engines.
 
iamlucky13
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Re: Potential that A220 is grounded following new engine issues ?

Thu Sep 19, 2019 9:32 pm

Etheereal wrote:
Nicoeddf wrote:
IFSDs don't kill people.


[citation needed]


It is covered under 14 CFR 25.901 and 25.903, which requires single failure or probable combinations of failures not jeopardize the safe operation of the aircraft.

It is possible for an in-flight shutdown to be a contributing factor, but other, improbable failures are necessary. See TransAsia 235 for an example. In that cause, the other failure was a major crew mistake intended to be made highly improbable by training.

Because an uncontained failure can by itself jeopardize the aircraft, it is a distinct case with far more stringent requirements.

Cubsrule wrote:
zeke wrote:
An engine issue by itself should never ground an aircraft, engines are certified separately to the airframe, and have their own TCDS.

As long as the airframe handles the engine out situation correctly, which the A220 seems to be doing getting back to the ground performing correctly I don’t see the basis for the airframe to be grounded.


The standard isn't (and shouldn't be) that "the airplane can get on the ground after the failure in ideal conditions if the pilots do everything right." After all, if that were the standard wouldn't the MAX be flying?


zeke neither said nor implied, "in ideal conditions if the pilots do everything right." Why did you add those words to your response?
 
iamlucky13
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Re: Rumour: A220 GTF IFSD

Thu Sep 19, 2019 9:34 pm

mjoelnir wrote:
iamlucky13 wrote:
Nicoeddf wrote:

Parts of the HPC going through HPT is not uncontained. Where else would parts from the HPC go, but downstream with the airflow? I have seen plenty of engines with totally destroyed core engines due to a single blade rupture upstream. Nothing uncontained in that.

The Trent 900 losing its IPT disc over Indonesia - that is uncontained.


I'm not even sure if Southwest 1380 is technically considered an uncontained failure. In that case, the fan blade apparently bounced forward after hitting the fan casing, destroying the inlet cowling, pieces of which damaged the wing and fuselage, leading to the death of one passenger.

As I've seen the term used in the past, an uncontained failure is one where the protections against parts being ejected at high speeds radially fail:
* Fan casing needs to be able to withstand impacts from failed fan blades
* Compressor and turbine need to be designed, quality controlled, and maintained not to fail, as the speed and density of the parts involved are impractical to reliably contain.

Southwest 1380 was an unusual case where, as far as I know, the casing withstood the impacts, but the parts happened to find their way around the case while still having enough momentum to pose a significant danger to the aircraft and occupants.

These recent GTF issues don't sound comparable from the details provided so far.


Southwest 1380 is exactly that, an uncontained failure. Pieces of the engine were ejecting radially hitting the fuselage. Exactly the definition of an uncontained engine failure and that accident was defined as that.
The fuselage was pierced, a cabin window smashed and the person pulled out of the window died.

There is no comparison to the failures on the various GTF engines, that were all contained, with in the worst case, pieces ejected through the tail pipe of the engine.

If engine failures would lead to grounding, the number 1 candidate should have been the 737NG with CFM56-7 engines.


Part of my reason for the uncertainty on the use of the term with respect to WN1380 is the NTSB report and the FAA emergency airworthiness directive on the incident don't use the term "uncontained."

Yes, parts were ejected radially at high speed, but not due to failure of the protections in place against that. The NTSB report in fact highlights the fact that the containment ring was intact. It seems to me more like what would have been categorized as an improbable combination of events.

But that's somewhat of a digression. My point was specifically to present an example a little different from a classic uncontained failure (like a hot section disc failure) that is clearly more serious than what has been occurring with the GTF.
 
SteelChair
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Re: Potential that A220 is grounded following new engine issues ?

Thu Sep 19, 2019 9:42 pm

litz wrote:
zeke wrote:
Cubsrule wrote:
But the A220 has only one engine type, no? So here, grounding the engine versus grounding the airframe is a distinction without a difference.


If there is an engine issue that warrants an AD, the AD will be issued against the engine not the airframe.

You should have seen how unreliable large piston engines were.


Or early jet engines.


Well yeah, but its 2019. The standard shouldn't be the 1940s-50s 4360 or the 1960-80s JT8D. It should be the 1980s CFM56 or the 2000s GE90-115. Somehow, I doubt the PW GTF will ever approach those levels of reliability....the 2037 and 4000 certainly didn't. But we don't really know about the GTF because PW isn't releasing any statistics. What are they hiding?

As for grounding......thats ridiculous imho. We are a long way from that imho. A lllloooooonnngggg way.
 
Cubsrule
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Re: Potential that A220 is grounded following new engine issues ?

Thu Sep 19, 2019 10:00 pm

iamlucky13 wrote:
Etheereal wrote:
Nicoeddf wrote:
IFSDs don't kill people.


[citation needed]


It is covered under 14 CFR 25.901 and 25.903, which requires single failure or probable combinations of failures not jeopardize the safe operation of the aircraft.

It is possible for an in-flight shutdown to be a contributing factor, but other, improbable failures are necessary. See TransAsia 235 for an example. In that cause, the other failure was a major crew mistake intended to be made highly improbable by training.

Because an uncontained failure can by itself jeopardize the aircraft, it is a distinct case with far more stringent requirements.

Cubsrule wrote:
zeke wrote:
An engine issue by itself should never ground an aircraft, engines are certified separately to the airframe, and have their own TCDS.

As long as the airframe handles the engine out situation correctly, which the A220 seems to be doing getting back to the ground performing correctly I don’t see the basis for the airframe to be grounded.


The standard isn't (and shouldn't be) that "the airplane can get on the ground after the failure in ideal conditions if the pilots do everything right." After all, if that were the standard wouldn't the MAX be flying?


zeke neither said nor implied, "in ideal conditions if the pilots do everything right." Why did you add those words to your response?


I’m not buying the idea that a failure mode that leads to IFSD cannot possibly lead to a grounding (which is a long way from saying that the A220 ought to be grounded). We seem to have here a failure mode that manifests at cruise and is relatively less dangerous, but what about a failure mode that leads to shutdowns at or around the time of rotation? That’s a far different situation, I think.
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Nicoeddf
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Re: Potential that A220 is grounded following new engine issues ?

Fri Sep 20, 2019 12:57 pm

Etheereal wrote:
Nicoeddf wrote:
IFSDs don't kill people.


[citation needed]


Nope. No citation needed. Basic knowledge of the industry, certification requirements and safety regulations suffice.

If an IFSD as single cause could lead to killing people, it wouldn't be certifiable.
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VV
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Re: Potential that A220 is grounded following new engine issues ?

Fri Sep 20, 2019 5:10 pm

Nicoeddf wrote:
...
IFSDs don't kill people. Flawed control logic and missing oversight do. Why would a grounding be considered?


Why?
 
iamlucky13
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Re: Potential that A220 is grounded following new engine issues ?

Fri Sep 20, 2019 6:21 pm

Cubsrule wrote:
iamlucky13 wrote:
Cubsrule wrote:

The standard isn't (and shouldn't be) that "the airplane can get on the ground after the failure in ideal conditions if the pilots do everything right." After all, if that were the standard wouldn't the MAX be flying?


zeke neither said nor implied, "in ideal conditions if the pilots do everything right." Why did you add those words to your response?


I’m not buying the idea that a failure mode that leads to IFSD cannot possibly lead to a grounding (which is a long way from saying that the A220 ought to be grounded). We seem to have here a failure mode that manifests at cruise and is relatively less dangerous, but what about a failure mode that leads to shutdowns at or around the time of rotation? That’s a far different situation, I think.


It's not a different situation. It is exactly the sort of the situation that has to be considered and is part of the regular certification process. If a shutdown occurs during takeoff, the certification requires the plane be able to safely reject takeoff or continue it as necessary. There are critical decision speeds the pilot is required to be aware of and practice in order to know ahead of time, if something goes wrong, do they continue takeoff, or abort?
 
Cubsrule
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Re: Potential that A220 is grounded following new engine issues ?

Fri Sep 20, 2019 6:36 pm

iamlucky13 wrote:
Cubsrule wrote:
iamlucky13 wrote:

zeke neither said nor implied, "in ideal conditions if the pilots do everything right." Why did you add those words to your response?


I’m not buying the idea that a failure mode that leads to IFSD cannot possibly lead to a grounding (which is a long way from saying that the A220 ought to be grounded). We seem to have here a failure mode that manifests at cruise and is relatively less dangerous, but what about a failure mode that leads to shutdowns at or around the time of rotation? That’s a far different situation, I think.


It's not a different situation. It is exactly the sort of the situation that has to be considered and is part of the regular certification process. If a shutdown occurs during takeoff, the certification requires the plane be able to safely reject takeoff or continue it as necessary. There are critical decision speeds the pilot is required to be aware of and practice in order to know ahead of time, if something goes wrong, do they continue takeoff, or abort?


So you think shutdowns at Vef are no more dangerous than shutdowns at cruise?
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iamlucky13
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Re: Potential that A220 is grounded following new engine issues ?

Fri Sep 20, 2019 7:43 pm

Cubsrule wrote:
iamlucky13 wrote:
Cubsrule wrote:

I’m not buying the idea that a failure mode that leads to IFSD cannot possibly lead to a grounding (which is a long way from saying that the A220 ought to be grounded). We seem to have here a failure mode that manifests at cruise and is relatively less dangerous, but what about a failure mode that leads to shutdowns at or around the time of rotation? That’s a far different situation, I think.


It's not a different situation. It is exactly the sort of the situation that has to be considered and is part of the regular certification process. If a shutdown occurs during takeoff, the certification requires the plane be able to safely reject takeoff or continue it as necessary. There are critical decision speeds the pilot is required to be aware of and practice in order to know ahead of time, if something goes wrong, do they continue takeoff, or abort?


So you think shutdowns at Vef are no more dangerous than shutdowns at cruise?


No, nor did I say such a thing. It's that the situation of a shut-down in cruise isn't the limiting design scenario. Since you are familiar with Vef, I hope we are getting close to clarifying the logic:

Vef effectively defines the worst case condition you have to be certified against for engine failure. The plane is required to be reasonably flyable by a properly trained pilot in all allowable conditions.

A shut down in cruise does not create new concerns about the possibility of a shutdown at Vef because that concern was already taken into account. The plane is designed to handle a shutdown at Vef.

It does not require ideal conditions and a pilot who does absolutely everything right. Rather it requires the conditions the aircraft is allowed to fly in, and a pilot who does the necessary things right, which they are trained on specifically because it is a critical situation.
 
Cubsrule
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Re: Potential that A220 is grounded following new engine issues ?

Fri Sep 20, 2019 7:50 pm

iamlucky13 wrote:
Cubsrule wrote:
iamlucky13 wrote:

It's not a different situation. It is exactly the sort of the situation that has to be considered and is part of the regular certification process. If a shutdown occurs during takeoff, the certification requires the plane be able to safely reject takeoff or continue it as necessary. There are critical decision speeds the pilot is required to be aware of and practice in order to know ahead of time, if something goes wrong, do they continue takeoff, or abort?


So you think shutdowns at Vef are no more dangerous than shutdowns at cruise?


No, nor did I say such a thing. It's that the situation of a shut-down in cruise isn't the limiting design scenario. Since you are familiar with Vef, I hope we are getting close to clarifying the logic:

Vef effectively defines the worst case condition you have to be certified against for engine failure. The plane is required to be reasonably flyable by a properly trained pilot in all allowable conditions.

A shut down in cruise does not create new concerns about the possibility of a shutdown at Vef because that concern was already taken into account. The plane is designed to handle a shutdown at Vef.

It does not require ideal conditions and a pilot who does absolutely everything right. Rather it requires the conditions the aircraft is allowed to fly in, and a pilot who does the necessary things right, which they are trained on specifically because it is a critical situation.


This all makes sense to me, and it gets us back to where we started, which was a comparison to the MAX. There, we had at least one crash where the pilots did not do the necessary things right lead to a grounding. It sounds like we agree that a similar situation is theoretically possible with IFSDs (though, again, I don't think we are anywhere near that point on the A220).
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Nicoeddf
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 2:23 am

Cubsrule wrote:
iamlucky13 wrote:
Cubsrule wrote:

So you think shutdowns at Vef are no more dangerous than shutdowns at cruise?


No, nor did I say such a thing. It's that the situation of a shut-down in cruise isn't the limiting design scenario. Since you are familiar with Vef, I hope we are getting close to clarifying the logic:

Vef effectively defines the worst case condition you have to be certified against for engine failure. The plane is required to be reasonably flyable by a properly trained pilot in all allowable conditions.

A shut down in cruise does not create new concerns about the possibility of a shutdown at Vef because that concern was already taken into account. The plane is designed to handle a shutdown at Vef.

It does not require ideal conditions and a pilot who does absolutely everything right. Rather it requires the conditions the aircraft is allowed to fly in, and a pilot who does the necessary things right, which they are trained on specifically because it is a critical situation.


This all makes sense to me, and it gets us back to where we started, which was a comparison to the MAX. There, we had at least one crash where the pilots did not do the necessary things right lead to a grounding. It sounds like we agree that a similar situation is theoretically possible with IFSDs (though, again, I don't think we are anywhere near that point on the A220).


No, we don't agree here. Engine failure at Vef is a very straight forward failure mode and trained in the simulator until you wanna puke every time you hear engine failure. The characteristics and physics of an engine failure are known and therefore the required "necessary" actions by the average pilot in non-ideal but certified conditions are as straight forward as the failure itself.

In the MAX scenario, a new inappropirately designed control logic combined with inappropriate communication to airlines and non-existent SIM training on the matter led to crews not doing the "necessary" things.

Very, very different.
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Cubsrule
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 2:48 am

Nicoeddf wrote:
Cubsrule wrote:
iamlucky13 wrote:

No, nor did I say such a thing. It's that the situation of a shut-down in cruise isn't the limiting design scenario. Since you are familiar with Vef, I hope we are getting close to clarifying the logic:

Vef effectively defines the worst case condition you have to be certified against for engine failure. The plane is required to be reasonably flyable by a properly trained pilot in all allowable conditions.

A shut down in cruise does not create new concerns about the possibility of a shutdown at Vef because that concern was already taken into account. The plane is designed to handle a shutdown at Vef.

It does not require ideal conditions and a pilot who does absolutely everything right. Rather it requires the conditions the aircraft is allowed to fly in, and a pilot who does the necessary things right, which they are trained on specifically because it is a critical situation.


This all makes sense to me, and it gets us back to where we started, which was a comparison to the MAX. There, we had at least one crash where the pilots did not do the necessary things right lead to a grounding. It sounds like we agree that a similar situation is theoretically possible with IFSDs (though, again, I don't think we are anywhere near that point on the A220).


No, we don't agree here. Engine failure at Vef is a very straight forward failure mode and trained in the simulator until you wanna puke every time you hear engine failure. The characteristics and physics of an engine failure are known and therefore the required "necessary" actions by the average pilot in non-ideal but certified conditions are as straight forward as the failure itself.

In the MAX scenario, a new inappropirately designed control logic combined with inappropriate communication to airlines and non-existent SIM training on the matter led to crews not doing the "necessary" things.

Very, very different.


So engine failure at Vef isn’t unsafe? Yeah, we’ll have to agree to disagree on that.
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fabian9
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 6:07 am

Nicoeddf wrote:
Parts of the HPC going through HPT is not uncontained. Where else would parts from the HPC go, but downstream with the airflow? I have seen plenty of engines with totally destroyed core engines due to a single blade rupture upstream. Nothing uncontained in that.


Uncontained engine rotor failure is a specific scenario that airframers look at where engine parts are penetrating radially away from the engine.

A failure where parts are ingested downstream and come out the back of the engine are considered “contained” engine failures.
 
Nicoeddf
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 9:03 am

fabian9 wrote:
Nicoeddf wrote:
Parts of the HPC going through HPT is not uncontained. Where else would parts from the HPC go, but downstream with the airflow? I have seen plenty of engines with totally destroyed core engines due to a single blade rupture upstream. Nothing uncontained in that.


Uncontained engine rotor failure is a specific scenario that airframers look at where engine parts are penetrating radially away from the engine.

A failure where parts are ingested downstream and come out the back of the engine are considered “contained” engine failures.


I know. Exactly what I wrote.
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Nicoeddf
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 9:06 am

Cubsrule wrote:
Nicoeddf wrote:
Cubsrule wrote:

This all makes sense to me, and it gets us back to where we started, which was a comparison to the MAX. There, we had at least one crash where the pilots did not do the necessary things right lead to a grounding. It sounds like we agree that a similar situation is theoretically possible with IFSDs (though, again, I don't think we are anywhere near that point on the A220).


No, we don't agree here. Engine failure at Vef is a very straight forward failure mode and trained in the simulator until you wanna puke every time you hear engine failure. The characteristics and physics of an engine failure are known and therefore the required "necessary" actions by the average pilot in non-ideal but certified conditions are as straight forward as the failure itself.

In the MAX scenario, a new inappropirately designed control logic combined with inappropriate communication to airlines and non-existent SIM training on the matter led to crews not doing the "necessary" things.

Very, very different.


So engine failure at Vef isn’t unsafe? Yeah, we’ll have to agree to disagree on that.


Exactly. It isn't unsafe. It is a certified scenario well within the design envelope plus margin.

If you cannot understand that failures within the design envelope are safe, we might want to end the argument here.
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Faro
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 9:29 am

Nicoeddf wrote:
Exactly. It isn't unsafe. It is a certified scenario well within the design envelope plus margin.

If you cannot understand that failures within the design envelope are safe, we might want to end the argument here.



IMHO for an engine to be grounded you would have to experience multiple instances of technically identical engine failures involving uncontained disintegration of fans, compressors or turbines, ie engine failures that pose a direct and immediate threat to the integrity of fuel tanks or the fuselage walls and pressure vessel.

All other engine failure scenarios are dealt with under QRH headings of emergency/abnormal ops, ie they are nominal contingencies and not strongly fatality-prone inflight incidents...


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wjcandee
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Re: Rumour: A220 GTF IFSD

Sat Sep 21, 2019 9:43 am

Well it looks like the rumor is now confirmed.

From an update at the same link to AvHerald provided in the first post in this thread:

"On Sep 19th 2019 the NTSB reported the aircraft sustained a left engine (PW1524G) failure just prior to reaching the top of climb at FL350. The crew worked the related checklists, shut the engine down and returned to Geneva. A post flight inspection revealed a hole in the low pressure compressor case and a separated low pressure compressor stage 1 rotor. There were no injuries. The NTSB accepted the delegation of the investigation by the French BEA and the Swiss SUST. The occurrence is rated an incident and is being investigated by the NTSB."
 
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Re: Rumour: A220 GTF IFSD

Sat Sep 21, 2019 9:49 am

wjcandee wrote:
Well it looks like the rumor is now confirmed.

From an update at the same link to AvHerald provided in the first post in this thread:

"On Sep 19th 2019 the NTSB reported the aircraft sustained a left engine (PW1524G) failure just prior to reaching the top of climb at FL350. The crew worked the related checklists, shut the engine down and returned to Geneva. A post flight inspection revealed a hole in the low pressure compressor case and a separated low pressure compressor stage 1 rotor. There were no injuries. The NTSB accepted the delegation of the investigation by the French BEA and the Swiss SUST. The occurrence is rated an incident and is being investigated by the NTSB."


Title has been updated accordingly.
 
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Faro
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Re: Rumour: A220 GTF IFSD

Sat Sep 21, 2019 9:50 am

wjcandee wrote:
Well it looks like the rumor is now confirmed.

"On Sep 19th 2019 the NTSB reported the aircraft sustained a left engine (PW1524G) failure just prior to reaching the top of climb at FL350."



IIRC, Lightsaber once indicated that top of climb is the most demanding flight regime for the compressor...sustained high engine RPM combined with rarefied, low density airflow...

Hope for the GTF this was a one-off...

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fabian9
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 10:33 am

Nicoeddf wrote:
I know. Exactly what I wrote.


Ah - apologies I misread your post. :)
 
VV
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Re: Confirmed: LX A220 GTF IFSD on September 16th, 2019

Sat Sep 21, 2019 11:22 am

I think we need to look into it a little bit differently.

Yes, the PW100G family of engines has issues and some are quite serious. It does not seem there are fundamental flaw in the design (or is there?), but there are obviously things to be done including some redesign of engine parts for the whole family.

Therefore Pratt & Whitney will have to do something to improve the situation.

Today, I have a lot of question as how much money those issues will cost to Pratt & Whitney.
  1. There will be compensation due to delivery delays
  2. There will be compensation due to service disruption
  3. There are costs related to the warranty
  4. Cost for part redesign and introduction of the correction to all the aircraft in the fleet (A320neo, A220, E2 and so on

How much all those items will cost Pratt & Whitney? I do not even want to talk about the reputation.
How much cash would be drained from the company in the next four years? Five hundred million dollars? One billion dollar? Three billion dollars? Who knows?

There is not any in-service aircraft with the smallest engines of the family that is PW1900G (E175-E2) and PW1200G (SpaceJet - Mitsubishi). In my opinion if there is any sacrificial lamb in order to save the whole PW1000G program, it would be both PW1200G and PW1900G. If ever Pratt & Whitney decides to mothball the development of the PW1200G and PW1900G then E175-E2 and SpaceJet would not have the engines ready on time.

From this point, I ask these questions very seriously.
  1. Will E175-E2 and SpaceJet be postponed to a date later than 2023?
  2. What would happen if Pratt & Whitney decides to cancel PW1200G and PW1900G altogether?

In my humble opinion, Pratt & Whitney needs to think seriously about putting the focus on PW1100G, PW1500G and PW1700G before spending too much time and money on PW1200G (SpaceJet) and PW1900G (E175-E2).

I know this is a very controversial comment, but it is not unrealistic.
 
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Faro
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Re: Rumour: A220 GTF IFSD

Sat Sep 21, 2019 11:26 am

wjcandee wrote:
“A post flight inspection revealed a hole in the low pressure compressor case and a separated low pressure compressor stage 1 rotor.”



If that hole was the cause of the separated compressor stage and not its result, maybe we’re dealing with a (hopefully one-off) manufacturing defect and not a design issue...fingers crossed for the GTF...


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par13del
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 11:58 am

Sokes wrote:
If engine makers face the risk that plane types with new engines are withdrawn from service for occasional contained engine failures, there won't be any more new engine technology. One can't avoid real live testing as there may always be wrong assumptions in the testing procedure.

Slipper slope there, RR has "grounded" 787's the world over costing airlines and itself millions because of doing real life testing for sulfur in the atmosphere and its effects on its engines? I put grounded in quotes since the PC crowd may ask for a source that the a/c and or engine were actually grounded, honestly do not think I need to say parked and not flying while awaiting engine repairs as I assume on this aviation site everyone is aware of the issue.
 
Cubsrule
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 1:02 pm

Nicoeddf wrote:
Cubsrule wrote:
Nicoeddf wrote:

No, we don't agree here. Engine failure at Vef is a very straight forward failure mode and trained in the simulator until you wanna puke every time you hear engine failure. The characteristics and physics of an engine failure are known and therefore the required "necessary" actions by the average pilot in non-ideal but certified conditions are as straight forward as the failure itself.

In the MAX scenario, a new inappropirately designed control logic combined with inappropriate communication to airlines and non-existent SIM training on the matter led to crews not doing the "necessary" things.

Very, very different.


So engine failure at Vef isn’t unsafe? Yeah, we’ll have to agree to disagree on that.


Exactly. It isn't unsafe. It is a certified scenario well within the design envelope plus margin.

If you cannot understand that failures within the design envelope are safe, we might want to end the argument here.


Don’t you mean failures within the design envelope generally aren’t unsafe if handled properly by the pilots?
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Sokes
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 3:30 pm

par13del wrote:
Sokes wrote:
If engine makers face the risk that plane types with new engines are withdrawn from service for occasional contained engine failures, there won't be any more new engine technology. One can't avoid real live testing as there may always be wrong assumptions in the testing procedure.


Slipper slope there, RR has "grounded" 787's the world over costing airlines and itself millions because of doing real life testing for sulfur in the atmosphere and its effects on its engines? I put grounded in quotes since the PC crowd may ask for a source that the a/c and or engine were actually grounded, honestly do not think I need to say parked and not flying while awaiting engine repairs as I assume on this aviation site everyone is aware of the issue.


I can't understand how engines are "developed". Engine maker and plane maker agree to design a new plane and a new engine in so and so many years.
If the engine maker already knows how to achieve the promised compression ratio, why does it take so many years? And if the engine makers don't know yet, how can they promise?
B747, Tristar, A340 were all victims of false promises, even though the B747 finally found a proper engine. The GE90 for B777-300ER turned out better than planned. So it seems these "plans" are really "hopes". How does one plan research results anyway?
On the other side it seems not feasible to first design the engine and then wait a few years for a plane for it. If the engine is mostly functional, one starts manufacturing and hopes to find a solution for the weak spots soon. Or the engine maker says "sorry", like with Lockheed Tristar or A340.
The German industry promised the German railway to build trains that can lean in curves, so that trains can drive faster on old tracks. They finally gave it up. Even though there were a lot of trains delivered. It seems they hoped to fix the weak spots "soon".

"Cracking problems in the intermediate pressure (IPT) section of the turbine have plagued the engine since early 2016, five years after its launch. ... According to Horwood, the problem was caused by sulphurisation; a chemical process affecting the nickel alloy which comprises the IPT blades. ...
The geometry around the root of the IPT blade concentrated air sucked in by the engine’s compressor system, which in some parts of the world (notably Asia) contained higher levels of sulphur-containing pollutants than the engine had been tested with. The temperatures within the IPT and some of the specialised coatings on the blade may have exacerbated the problem, Horwood said, producing air turbulence and local temperature increases that led to fatigue-like behaviour in the metal which resulted in cracking."
https://www.theengineer.co.uk/rolls-roy ... rent-1000/

"The first run of the Trent 1000 was on 14 February 2006.[2] First flight on Rolls-Royce's own flying testbed (a modified Boeing 747-200) was successfully performed on 18 June 2007 from TSTC Waco Airport.[3] The engine received joint certification from the FAA and EASA on 7 August 2007[4] (7-8-7 in Europe).
The Trent 1000 is the launch engine on both initial 787 variants, the -8 with ANA and the -9 with Air New Zealand."
https://en.wikipedia.org/wiki/Rolls-Royce_Trent_1000

That RR did "real life testing for sulfur in the atmosphere" is possibly what I meant. In their assumptions this problem didn't appear. And the problem appeared five years after entry into service and nine years after first flight on the B747 testbed. I can't find fault with RR for this problem. Which is not to say that they are not responsible for the financial damage and for maintenance.
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MIflyer12
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Re: Potential that A220 is grounded following new engine issues ?

Sat Sep 21, 2019 5:26 pm

Sokes wrote:
I can't understand how engines are "developed". Engine maker and plane maker agree to design a new plane and a new engine in so and so many years.
If the engine maker already knows how to achieve the promised compression ratio, why does it take so many years? And if the engine makers don't know yet, how can they promise?


Product attributes and outcomes get promised all the time before the engineering outline is complete, let alone testing complete. Most famously:

I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project...will be more exciting, or more impressive to mankind, or more important...and none will be so difficult or expensive to accomplish...” -President John F. Kennedy, May 1961

Some firms pretty reliably show an understanding of the basic sciences, their capabilities, and timelines. Some don't. If you're not failing now and then you're not pushing hard enough. Or you're cheating. https://www.theguardian.com/business/20 ... sions-tech
 
N212R
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Re: Rumour: A220 GTF IFSD

Sat Sep 21, 2019 10:38 pm

wjcandee wrote:
Well it looks like the rumor is now confirmed.


And to think you might have saved yourself all that exasperated hot air....must be the latest social media phenomenon; rumor confirmation bias. :D
 
Sokes
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Re: Potential that A220 is grounded following new engine issues ?

Sun Sep 22, 2019 3:44 am

MIflyer12 wrote:
...
If you're not failing now and then you're not pushing hard enough. Or you're cheating. ...


Amen to that. If you consider what I stated originally it is clear that we are in agreement:
"If engine makers face the risk that plane types with new engines are withdrawn from service for occasional contained engine failures, there won't be any more new engine technology. "
I started laughing when I read your Kennedy comment. Which I believe confirms the truth to what you want to say.
Is anybody surprised that Diesel cars pollute the environment? My nose always told me that. But then I generally rather don't believe in authorities. I do believe in my nose, though.
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Nicoeddf
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Re: Potential that A220 is grounded following new engine issues ?

Sun Sep 22, 2019 8:09 pm

Cubsrule wrote:
Nicoeddf wrote:
Cubsrule wrote:

So engine failure at Vef isn’t unsafe? Yeah, we’ll have to agree to disagree on that.


Exactly. It isn't unsafe. It is a certified scenario well within the design envelope plus margin.

If you cannot understand that failures within the design envelope are safe, we might want to end the argument here.


Don’t you mean failures within the design envelope generally aren’t unsafe if handled properly by the pilots?


Yes, in the same sense a landing within the envelope is only safe if handled correctly by the pilots.
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Cubsrule
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Re: Potential that A220 is grounded following new engine issues ?

Sun Sep 22, 2019 8:52 pm

Nicoeddf wrote:
Cubsrule wrote:
Nicoeddf wrote:

Exactly. It isn't unsafe. It is a certified scenario well within the design envelope plus margin.

If you cannot understand that failures within the design envelope are safe, we might want to end the argument here.


Don’t you mean failures within the design envelope generally aren’t unsafe if handled properly by the pilots?


Yes, in the same sense a landing within the envelope is only safe if handled correctly by the pilots.


Literally true, but awfully pedantic it seems to me. Engine failures on the edge of the design envelope are almost be definition less safe than failures well within the envelope. Otherwise the evelope wouldn't be where it is.
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Nicoeddf
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Re: Potential that A220 is grounded following new engine issues ?

Mon Sep 23, 2019 8:01 am

Cubsrule wrote:
Nicoeddf wrote:
Cubsrule wrote:

Don’t you mean failures within the design envelope generally aren’t unsafe if handled properly by the pilots?


Yes, in the same sense a landing within the envelope is only safe if handled correctly by the pilots.


Literally true, but awfully pedantic it seems to me. Engine failures on the edge of the design envelope are almost be definition less safe than failures well within the envelope. Otherwise the evelope wouldn't be where it is.


I appreciate our civilised argument despite disagreement, but I can't follow your logic here.
If engine failures would not be safe or "less safe" they wouldn't be certifiable. A/C are designed specifically to make an engine failure at V1 a "safe operation" with any average pilot even on a subpar day.
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zeke
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Re: Potential that A220 is grounded following new engine issues ?

Mon Sep 23, 2019 9:11 am

Cubsrule wrote:
Literally true, but awfully pedantic it seems to me. Engine failures on the edge of the design envelope are almost be definition less safe than failures well within the envelope. Otherwise the evelope wouldn't be where it is.


Not really true, there are buffers in the certification process to account not average pilot skill rather than test pilot skill. The "envelopes" are not really the maximum safe limits, they represent a buffer inside the maximum safe limit.
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Cubsrule
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Re: Potential that A220 is grounded following new engine issues ?

Mon Sep 23, 2019 11:33 am

Nicoeddf wrote:
Cubsrule wrote:
Nicoeddf wrote:

Yes, in the same sense a landing within the envelope is only safe if handled correctly by the pilots.


Literally true, but awfully pedantic it seems to me. Engine failures on the edge of the design envelope are almost be definition less safe than failures well within the envelope. Otherwise the evelope wouldn't be where it is.


I appreciate our civilised argument despite disagreement, but I can't follow your logic here.
If engine failures would not be safe or "less safe" they wouldn't be certifiable. A/C are designed specifically to make an engine failure at V1 a "safe operation" with any average pilot even on a subpar day.


That’s sort of why I’ve been talking about Vef (which, at least in the States, is defined as a critical point), not V1. You seem to be arguing that engine failures are not and cannot be unsafe. Have I got that right?
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Nicoeddf
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Re: Confirmed: LX A220 GTF IFSD on September 16th, 2019

Mon Sep 23, 2019 12:16 pm

Vef and/or V1 would be handled synonymously at the airline I happen to have most insight to - simply the most critical moment defined by various factors, at which the engine can fail during takeoff.

Yes, you got that right. The engine failure is not unsafe in itself.
Improper handling by the crew make an engine failure unsafe.
But then again, any improper handled situation, even in routine operation is unsafe by definition.
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CHRISBA35X
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Re: Confirmed: LX A220 GTF IFSD on September 16th, 2019

Mon Sep 23, 2019 12:18 pm

I have the sense a few folks from that side of the Atlantic will be keen to see a grounding here - sad really. Fingers crossed its not a major issue.
 
runway23
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Re: Confirmed: LX A220 GTF IFSD on September 16th, 2019

Tue Oct 15, 2019 1:52 pm

Another engine failure today and the aircraft is now grounded by Swiss - as I had speculated 3 weeks ago.
 
LSZH34
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Re: Confirmed: LX A220 GTF IFSD on September 16th, 2019

Tue Oct 15, 2019 1:58 pm

It's only a matter of time (if not already) until the A220 will suffer from an increasingly bad reputation as the 737MAX.
 
FlyHPN
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Re: Confirmed: LX A220 GTF IFSD on September 16th, 2019

Tue Oct 15, 2019 2:09 pm

LSZH34 wrote:
It's only a matter of time (if not already) until the A220 will suffer from an increasingly bad reputation as the 737MAX.

At this point I think putting it on the same levels as the 737MAX would be unfair. Perhaps, it’s almost at the level of the early Dreamliners. But then consider: if you were to ask the public if they have heard of the A220, Dreamliner/787, or 737MAX, there will be a resounding margin between MAX and the others.

That said, safety has to be the #1 priority. If Pratt doesn’t have the issue identified and a fix on the way, perhaps a grounding is warranted. I am not knowledgeable enough to comment any further on the subject.
 
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madpropsyo
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Re: Confirmed: LX A220 GTF IFSD on September 16th, 2019

Tue Oct 15, 2019 2:15 pm

CHRISBA35X wrote:
I have the sense a few folks from that side of the Atlantic will be keen to see a grounding here - sad really. Fingers crossed its not a major issue.


The 220 is a North American aircraft with North American engines. "That side of the Atlantic"?

If the IFSDs are frequent enough there will be guidance on how to operate/ground until fixes are in place much like with the RR 787 debacle. The A220 can be ETOPS certified and it isn't a good idea to have engines that are known to be dodgy on an airplane out over the ocean. This is exactly the sort of situation that this message board has been advocating for regulators to step in and do their jobs to protect the flying public and yet because the 220 is now an "Airbus" in name this thread is made up mostly of posts like "MAX bad, Airbus safe". The goalkeeping is ridiculous.
 
Amiga500
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Re: Potential that A220 is grounded following new engine issues ?

Tue Oct 15, 2019 2:30 pm

Amiga500 wrote:
Cubsrule wrote:
But the A220 has only one engine type, no? So here, grounding the engine versus grounding the airframe is a distinction without a difference.


You ground the engine if there is evidence of a systematic failure that means there is a significant chance of losing both engines on an aircraft in any flight.

Given evidence to date, doesn't look like we are there.


Looks like Swiss must believe we are there now...
 
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Re: Confirmed: LX A220 GTF IFSD on September 16th, 2019

Tue Oct 15, 2019 3:12 pm

Please continue your discussion here:

viewtopic.php?f=3&t=1433093

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