Egerton
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A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 11:38 am

How bad will this P&W snafu get? The production rate of the upgraded neo airframe is rising, but what about the Pratt engines production rate?

1. Will there soon be 100 A320npe series aeroplanes parked at Toulouse for want of engines?
2. How many months will pass before the build rate of good engines exceed the build rate of neo airframes?
3. Can the ceo engine suppliers up their delivery rate pronto?
4. Can Airbus up the proportion of ceo airframes pronto?
5. What are the cash flow implications and who will pay?

Is this beginning to look like the 787 snafu, but most of the blame goes to Pratt?

http://www.airbus.com/presscentre/ho...pics/annual-press-conference-2016/

[Edited 2016-01-24 03:40:25]

[Edited 2016-01-24 03:44:14]
 
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JerseyFlyer
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 1:01 pm

If this is the case it won't be the first time PW has snafu'd Airbus:

1 Superfan sole engine anticipated for A340, failed and replaced by CFM 56

2 PW 6000 sole engine anticipated for A318, delayed by massive re-design, replaced by CFM 56

At least there is a CFM option ready to fly this time!
 
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 1:53 pm

Quoting JerseyFlyer (Reply 1):
At least there is a CFM option ready to fly this time

The CFM option is only "ready" if you talk about the ceo, otherwise the wait is to the summer.
 
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lightsaber
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 4:12 pm

Pratt accelerated the EIS by a year and there were snafus. As best as I know there are two holdups.
1. Most operators are waiting for the sofware fix. So Pratt is making engines and will deliver with the upgraded software. Only LH (so far) was willing to take the risk of the muti-hour hold if the windmilling doesn't get started on schedule.
2. The seal ring. Pratt is scrambling to remove them and have them heat treated. This is keeping basically built engines at the assembly sites. Since Pratt personally owns a surplus of heat treating capacity, they have easy options to fix the issue. But it will still take time.

Quoting JerseyFlyer (Reply 1):

If this is the case it won't be the first time PW has snafu'd Airbus:

Sadly you forgot:
3. PW4175 launched as the PW4170 (eventually to PW4172). Pratt lost most of their A330 customer base in that snafu.

However, Pratt and Airbus work well together developing concepts.

The Pratt GTF will be in mass production far earlier than CFM's LEAP-1A.

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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 4:42 pm

Quoting Egerton (Thread starter):
Is this beginning to look like the 787 snafu, but most of the blame goes to Pratt?

Actually the 747-100 would be a more apt comparison, as many frames were delayed due to lack of Pratt & Whitney JT9D-3A engines.
 
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 4:59 pm

Quoting Stitch (Reply 4):

Quoting Egerton (Thread starter):
Is this beginning to look like the 787 snafu, but most of the blame goes to Pratt?

Actually the 747-100 would be a more apt comparison, as many frames were delayed due to lack of Pratt & Whitney JT9D-3A engines.

The original JT9D-3A powered 747-100s were grounded for a few weeks due to problems. Northwest Airlines had several very early new 747-151s sitting around grounded while Pratt & Whitney fixed the problem. I do not remember what is was.
Also, Lufthansa was having so many problems, including lack of parts and support, with their Pratt powered 747-130s that they traded them in on new GE CFM-6 powered 747-230s. Northwest Airlines wanted to acquire them and Boeing would not sell them to Northwest.   

[Edited 2016-01-24 09:00:45]
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 5:58 pm

Put your trust in God and Pratt and Whitney!
 
Egerton
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 6:10 pm

http://uk.reuters.com/article/uk-air...us-lufthansa-idUKKBN0UD1IH20151230

Pratt & Whitney spokeswoman Sara Banda said the company had plans to incorporate "software refinements and minor hardware modifications" in production engines starting in the second quarter of 2016.

This above was dated 30.12.2015.

If airlines in general (exclude LH) are reluctant to accept the engines without the mods, then it seems a long period of perhaps many weeks will go by without any A320npe aeroplanes being in a deliverable condition?

If the build rate of new airframes at the input end of the production line is rising to say 10 per month soon, there will be a big number, maybe 50npe, parked at Toulouse before things may start to get back under control?

Perhaps this explains why Indigo is planning for the short term lease of up to 22 A320ceo to make good the shortfall in deliveries of their neo?

[Edited 2016-01-24 10:12:04]

[Edited 2016-01-24 10:13:20]
 
mjoelnir
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 6:26 pm

Quoting Egerton (Reply 7):
Pratt & Whitney spokeswoman Sara Banda said the company had plans to incorporate "software refinements and minor hardware modifications" in production engines starting in the second quarter of 2016.

That is only one of the statement in the article.

The other statement was :

Earlier this month, UTC Chief Executive Gregory Hayes said that uneven cooling of the engine after flight required a special restart procedure under some circumstances.
Hayes said software and hardware fixes were in the works and would likely be implemented by February.

The difference between those statements can be: earlier engines have to be fixed and that starts in February, and later production engines from second quarter 2016 and on include the fix.

I imagine that already between 10 and 20 frames are waiting for engines or the fix.
 
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 6:31 pm

G'day

Quoting Egerton (Reply 7):
Indigo is planning for the short term lease of up to 22 A320ceo

If all those 22 A320ceo's are required to compensate for the late delivery of the A320NEO's that indicates they are not expecting any A320NEO deliveries in the next months or even this year. How many A320NEO's do they have scheduled for delivery this year?

Sounds like a real f****p   

Cheers

Peter
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 8:53 pm

Quoting Heavierthanair (Reply 9):
Quoting Heavierthanair (Reply 9):
G'day

Quoting Egerton (Reply 7):
Indigo is planning for the short term lease of up to 22 A320ceo

If all those 22 A320ceo's are required to compensate for the late delivery of the A320NEO's that indicates they are not expecting any A320NEO deliveries in the next months or even this year. How many A320NEO's do they have scheduled for delivery this year?

Sounds like a real f****p   

Cheers

Peter

About 6 Indigo frames with or without engines are waiting as it is. One was used by Airbus for route proving. At least one more has done its first flight. 2 more frames should be nearing completion,

As how many were expected this year, my guess would be about 40, ten each quarter in 2016.
 
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 9:10 pm

Quoting Egerton (Thread starter):
mes:

How bad will this P&W snafu get? The production rate of the upgraded neo airframe is rising, but what about the Pratt engines production rate?

What snafu are you talking about? I don't know what your link is referring to. What engine production rate problems?

I have only heard of relatively minor problems. The PW1100G has some uneven cooling problems. While these can be very difficult to solve, they are somewhat common. Uneven rotor (bowed rotor) is a problem on many turbine engines. Things often warp when cooling. The PW engine has the gearbox to complicate things but also fewer stages. I don't think this is too significant of a problem compared to ice crystal icing on the GEnx or the challenge (including financial) with the three spool design on the RB211. While GEnx will be solved through software, three spool promised to be innovative and lead to massive benefits for Rolls Royce, which while good, never materialized into the expected success. The PW1100G could end up like those engines, but I don't see evidence yet that they will have such technical challenges.
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Egerton
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 9:43 pm

I guessed that you had seen this From KarelXWB on 21.01.2015 on the Airbus A320neo Production Thread - Part 9:

Quoting Aviaponcho (Reply 57):
How many stored at TLS and how many at XFW ?


Too much, I'm not counting them anymore.

At least 10 IndiGo A320neo's have been spotted, together with 2 Spirit, 2 Qatar and 3 Lufthansa.

Hope this helps?
 
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KarelXWB
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 10:02 pm

Quoting Egerton (Thread starter):
1. Will there soon be 100 A320npe series aeroplanes parked at Toulouse for want of engines?

And XFW too.
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 10:13 pm

How far behind is Pratt on engine manufacturing? Is it due to the cooling issue or the retainer ring? I have not seen an articles describing the technical story for what is going on with Pratt production.
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 10:17 pm

Quoting roseflyer (Reply 14):
How far behind is Pratt on engine manufacturing?

Pratt must have produced at least two dozen production engines. Customers are most likely waiting for the software fix, due to arrive next month.
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 10:54 pm

Quoting Egerton (Thread starter):

2. How many months will pass before the build rate of good engines exceed the build rate of neo airframes?

Is there a production rate problem?
If you have never designed an airplane part before, let the real designers do the work!
 
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KarelXWB
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 10:58 pm

And what do you mean with "good engines" if the issue can be resolved with a software update?
What we leave behind is not as important as how we've lived.
 
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 11:04 pm

Quoting KarelXWB (Reply 17):
And what do you mean with "good engines" if the issue can be resolved with a software update?


I don't know. That is why I am asking the question. I don't understand the original thread start post.
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 11:11 pm

Quoting KarelXWB (Reply 17):
And what do you mean with "good engines" if the issue can be resolved with a software update?

There seem to be both a software and hardware fix to be applied together.
 
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 11:41 pm

Quoting mjoelnir (Reply 19):

A pure software fix would not prohibit hanging engines.

While an open hardware fix makes hanging engines a dumb thing.
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RE: A320npe No Pratt Engines. What Next?

Sun Jan 24, 2016 11:47 pm

Quoting Egerton (Thread starter):

Is this beginning to look like the 787 snafu, but most of the blame goes to Pratt?

No, this reminds me of the 747 SNAFU when the plane was ready and there were no PW engines to hang from the pylons. The 747 went on to become arguably the most successful widebody airliner program and certainly the most iconic widebody airliner.
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 3:42 am

Quoting mjoelnir (Reply 19):
There seem to be both a software and hardware fix to be applied together.

Correct.

The Seal Ring is being hardened to address the oil issues. My understanding on the Software fix is it's for certain unique internal thermal conditions. This can present issues at start under a specific set of conditions. While I am not certain, my understanding is the thermal anomaly lies with the Reduction Gear Box, and it's ability to cool.

This is not an unknown in the design of a Geared Turbofan. It will be interesting to see how it will be addressed through Software.
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 5:59 am

Quoting Egerton (Reply 7):
50npe

If your going to create a new term specific to the engine manufacturer would A320peo & A320geo not be more appropriate as Pratt Engine Option makes more sense than New Pratt Option as engine option is the important part of neo not the new part?
 
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 6:43 am

Quoting lightsaber (Reply 3):

Pratt accelerated the EIS by a year and there were snafus. As best as I know there are two holdups.
1. Most operators are waiting for the sofware fix. So Pratt is making engines and will deliver with the upgraded software. Only LH (so far) was willing to take the risk of the muti-hour hold if the windmilling doesn't get started on schedule.

Can you expound on this? What is this "cold temperature windmilling" thing I keep hearing about?
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 6:48 am

Quoting DocLightning (Reply 25):

Can you expound on this? What is this "cold temperature windmilling" thing I keep hearing about?

8 minutes of turning turbine unlit to equalisle tempterutes across a bearing / seal set.
BV
 
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 10:12 am

Quoting DocLightning (Reply 21):
No, this reminds me of the 747 SNAFU when the plane was ready and there were no PW engines to hang from the pylons. The 747 went on to become arguably the most successful widebody airliner program and certainly the most iconic widebody airliner.

  


A thread dedicated to early problems with the 747's first JT9D-3 engines is here:

What Exactly Was The Problem With Early JT9D-3's? (by Faro Jan 5 2010 in Tech Ops)

The relevant contribution from member 747classic follows:

""- 1) Under powered ,delivered not enough thrust for the ever increasing MTOW of the 747, to get maximum thrust HP turbine section was operated at limits.
- 2) Very sensitive for tail and X-wind, especially during starting, causing hot starts or stalls.
- 3) Ovalisation of the engine casing during T/O, causing blade rubbing and loss of efficiency.
- 4) In general very stall sensitive during power transitions, don't put the power levers suddenly to idle.
- 5) Damaged HP turbines, caused by failing rivets in blade-retaining plates in early engines.

Remedies :
- 1) Product development, slowly increased thrust from 43.500 lbs, first via addition of water injection in the dash -3A engine. Then further increase possible via improved HP turbine blades in dash 7, 7W, 7A, 7AW, 7F and finally maximum 50.000 lbs in dash 7J with single cristal HP turbine blades with improved cooling. Two improved variants (with different type certificate) with more thrust were developed to counteract the GE and RR engines offered from 1975. First the -70 and -7Q were developed, the final (at last matured) engine was the dash -7R4 series.
- 2) Small improvements made starting not so demanding, but still the engine was/is very tricky to start in tail wind conditions. (valid for all dash -7 versions up to -7J.)
- 3) Was remedied by a thrust yoke, to spread the forces applied between the pylon and engine better.
- 4) Addition of ARS (automatic recovery system) in fact extra (3.5) bleed valves dumping air, when an impending stall condition was sensed. During reverse RABS (reverse actuated bleed system) was built in to release air from the engine in case of impending stall.
- 5) Improved rivets installed.""


Faro
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KarelXWB
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 10:19 am

Quoting DocLightning (Reply 21):
No, this reminds me of the 747 SNAFU when the plane was ready and there were no PW engines to hang from the pylons.

There's this historical photo:

http://oi68.tinypic.com/svqfj5.jpg
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 12:31 pm

Quoting boeingVista (Reply 24):
As in nope, she ain't flying till Pratt get their shit together

Although somewhat paradoxically she actually did fly today - and in revenue service  

Rgds
 
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lightsaber
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 7:19 pm

Aagh!!!

This will get worse before it gets better.
At least from rumblings I'm now hearing.


Sigh...

Quoting DocLightning (Reply 25):
Can you expound on this? What is this "cold temperature windmilling" thing I keep hearing about?

The casing suffers differential cooling issues after the engine has been shut down an hour. (This was true of the CFM-56). Until the engine cools for three ours, the casing is warped and thus no starting the engine. By slowly windmilling the engine, the differential temperature is never bad enough to warp the casing. It is because the top of the engine gets hotter than the bottom.

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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 7:59 pm

Quoting lightsaber (Reply 30):
This will get worse before it gets better.
At least from rumblings I'm now hearing.

Oh dear - that sounds ominous.

Can you give us any clues as to what the rumblings are about? Is it the seal, the differential cooling, or something new?

Quoting lightsaber (Reply 30):
The casing suffers differential cooling issues after the engine has been shut down an hour. (This was true of the CFM-56). Until the engine cools for three ours, the casing is warped and thus no starting the engine. By slowly windmilling the engine, the differential temperature is never bad enough to warp the casing. It is because the top of the engine gets hotter than the bottom.

Are you sure it is the casing? I was convinced that I read about someone at Pratt saying the cooling issue was causing a shaft to warp, causing blade rubbing. Maybe I'm just getting senile.
 
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 8:10 pm

Quoting lightsaber (Reply 30):

Aagh!!!

This will get worse before it gets better.
At least from rumblings I'm now hearing.


From a level headed chap like you, it sounds like the numbers of npe (flightless birds) will grow before it shrinks?
Do please keep us informed as and when you are able. Thanks for your input so far.
 
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 8:11 pm

Quoting lightsaber (Reply 30):
Aagh!!!

This will get worse before it gets better.
At least from rumblings I'm now hearing.

I sure hope Indigo has got a quick exit route to the Leap.... Or a hefty compensation clause.
Racing, competing, is in my blood. It's part of me, it's part of my life; I've been doing it all my life. And it stands up before anything else- Ayrton Senna
 
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 9:36 pm

Quoting speedbored (Reply 31):
Can you give us any clues as to what the rumblings are about? Is it the seal, the differential cooling, or something new?

I don't know. The problems I know about should create the backlog of A320NPE I'm being told to expect.

Quoting speedbored (Reply 31):

Are you sure it is the casing? I

Ok, shaft relative to casing.  . Either way, the engine doesn't start.

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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 10:15 pm

http://economictimes.indiatimes.com/...eo-planes/articleshow/50710602.cms

Indigo supposedly asking for cheaper support from Pratt and Airbus instead of compensation..... I guess the line of customers asking for "stuff" may only get longer.
Racing, competing, is in my blood. It's part of me, it's part of my life; I've been doing it all my life. And it stands up before anything else- Ayrton Senna
 
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RE: A320npe No Pratt Engines. What Next?

Mon Jan 25, 2016 11:54 pm

Quoting lightsaber (Reply 3):
PW4175 launched as the PW4170 (eventually to PW4172).

Know about the 75 and the 72... but did the 4170 iteration ever EIS?
I myself, suspect a more prosaic motive... ~Thranduil
 
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 1:53 am

Quoting lightsaber (Reply 29):
The casing suffers differential cooling issues after the engine has been shut down an hour. (This was true of the CFM-56). Until the engine cools for three ours, the casing is warped and thus no starting the engine. By slowly windmilling the engine, the differential temperature is never bad enough to warp the casing. It is because the top of the engine gets hotter than the bottom.
Quoting lightsaber (Reply 33):
Ok, shaft relative to casing. . Either way, the engine doesn't start.
Quoting speedbored (Reply 30):
Are you sure it is the casing? I was convinced that I read about someone at Pratt saying the cooling issue was causing a shaft to warp, causing blade rubbing. Maybe I'm just getting senile.

Any of the above issuse MUST have become obvious to PW / Airbus way before now as in years ago so I'm confused as to how this has been allowed to develop into a show stopper for EIS.
BV
 
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 4:59 am

Lightsaber: are you NDAed as to how many planes in the backlog and for how long?

A few baker's dozens? A few seasons?
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 7:50 am

Quoting BoeingVista (Reply 36):
Any of the above issuse MUST have become obvious to PW / Airbus way before now as in years ago so I'm confused as to how this has been allowed to develop into a show stopper for EIS.

This is an issue that only exists in a particular time-window after engine shutdown - it develops as the engine cools past a particular point, and then rectifies itself as the engine cools further. I'm guessing that it is also affected by even simple things like ambient temperature, or maybe even wind through/around the engine after shutdown.

Given that almost all of the testing would have involved either relatively long, or relatively short, periods between shutdowns and restarts, it doesn't really surprise me to find that it didn't become apparent until late on in the test program. Again, I'm guessing, but I suspect that this issue first became apparent as the "minor rubbing of blades against the casing" issue that was reported towards the end of flight testing, and that it took a while to work out exactly what the underlying cause was.
 
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 8:21 am

Quoting speedbored (Reply 38):
This is an issue that only exists in a particular time-window after engine shutdown - it develops as the engine cools past a particular point, and then rectifies itself as the engine cools further. I'm guessing that it is also affected by even simple things like ambient temperature, or maybe even wind through/around the engine after shutdown.

JC, no, no,no.

This should have been an item in the basic testing plan. Can engine be safely restarted after 10min, 20, 30, 45, 60, 90... all the way down to cold. Oil, seals, shafts, gearboxes hot /cold are known issues with gas turbines if you are not testing these under all conditions you are not doing your job.
BV
 
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 9:18 am

Quoting BoeingVista (Reply 39):
This should have been an item in the basic testing plan. Can engine be safely restarted after 10min, 20, 30, 45, 60, 90... all the way down to cold. Oil, seals, shafts, gearboxes hot /cold are known issues with gas turbines if you are not testing these under all conditions you are not doing your job.

Perhaps, and maybe they did carry out such tests. But, from what we've heard, the deviation in the shaft caused by the cooling issue is tiny - thousandths of an inch - so it is not inconceivable that no blade rubbing became apparent under the particular conditions in which that testing was carried out.

Basically, all I'm saying is - let's not be in too much of a hurry to hang P+W out to dry until we know, for certain, a bit more about what the issue is, and how/why it went unnoticed for so long.

[Edited 2016-01-26 01:20:55]
 
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 9:36 am

Quoting BoeingVista (Reply 25):
8 minutes of turning turbine unlit to equalisle tempterutes across a bearing / seal set.

So when did it become 8 minutes? Previously, a report in December suggested three minutes:

http://www.reuters.com/article/us-ut...0TU02U20151211#xmz0psXObJKxY715.97

Three minutes seems tolerable, eight minutes makes Al Baker's decision to defer more understandable...
 
StTim
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 9:40 am

Aircraft often spend a few minutes after pushback before progressing. We do not know how much of that time was spent windmilling the engine before start up.
 
Egerton
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 12:00 pm

My take so far is that there seems to be issues which need changes to both hardware and software. If so, it would seem sensible that these changes should be thoroughly tested before airline use. In short, it does not seem wise to have paying passengers do the work of test pilots. This will take time, so be it. Better safe than sorry.

If memory serves me right, this rush to quick fix a CFM fan issue caused the 1989 Kegworth UK crash of a British Midland 737 with 47 deaths. The untested engine fix and consequent contained shedding of a fan blade was not helped by the shut down in error of the remaining good engine.
 
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lightsaber
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 12:10 pm

Quoting Aircellist (Reply 37):
Lightsaber: are you NDAed as to how many planes in the backlog and for how long?

A few baker's dozens? A few seasons?

No.

I do not work for Pratt or Airbus. I in the past worked for Pratt and thus will respect my NDAs. However, now it is contacts in the industry who inform me of events.

That said, all I have been told is contingency planning; planning that tells me the problem will get worse before it gets better. But the contingency planning I'm hearing about wouldn't be needed at the normally production to delivery pace...

My contact concentrate on the design and flight test of aircraft. This... is production. While I have some contacts, they are not of the quantity in other areas. If any of my contacts are working a problem, they will respect their NDA and not discuss the issue.

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speedbored
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 12:40 pm

Quoting lightsaber (Reply 44):
all I have been told is contingency planning

Well that sounds marginally better than disaster recovery planning.

Let's hope that it's "just in case" type contingency planning rather than "oh dear"  
 
Bambel
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 1:39 pm

Quoting AndyEastMids (Reply 41):
Three minutes seems tolerable, eight minutes makes Al Baker's decision to defer more understandable...

IIRC the cool-down only has to be done if the engine is restartet in a certain timeframe so if the schedule falls in that bracket couldn't this be done prior to pushback? On a 90 min turnaround you have 87 min to run the engine "cold", so why use the last 3 mins?

b.
 
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DocLightning
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 2:53 pm

Quoting speedbored (Reply 30):

Are you sure it is the casing? I was convinced that I read about someone at Pratt saying the cooling issue was causing a shaft to warp, causing blade rubbing. Maybe I'm just getting senile.

It seems to me like a requirement to windmill the engine for 8 minutes prior to starting when shut down for 1->3 hours would suggest a thermal deformation of a shaft, rather than the casing. Windmilling the shaft would serve as a "rotisserie" equalizing the temperature.

Obviously, a fix will have to be arranged so that 8 minutes before engine start, the engine is motored by the starting system. If that's the case, I wonder how dangerous it will be to have rampers working around the engine while it is motoring.
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lightsaber
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 3:26 pm

Quoting DocLightning (Reply 47):
I wonder how dangerous it will be to have rampers working around the engine while it is motoring.

As dangerous as the CFM-56 which applies the same fix.

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roseflyer
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RE: A320npe No Pratt Engines. What Next?

Tue Jan 26, 2016 3:53 pm

Quoting speedbored (Reply 40):

Basically, all I'm saying is - let's not be in too much of a hurry to hang P+W out to dry until we know, for certain, a bit more about what the issue is, and how/why it went unnoticed for so long.

Airlines are not patient when there are design deficiencies. They tend to be very demanding. While some are more public about the demands than others, I think the management changes including last week's sudden retirement announcement Robert Adams as president of Pratt over the GTF shows that something is going on. Unannounced retirements and sudden management shakeups imply there is someone being hung out to dry.

http://atwonline.com/engines/pratt-w...nt-changes-made-gtf-enters-service

[Edited 2016-01-26 07:57:57]
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