PPVRA
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Question About E-jets Engine Choice

Mon Mar 12, 2007 1:24 am

So I have heard numerous times that Embraer wanted a more efficient engine for the E-jets than the CF34s, but they didn't get it.

Today, we hear from Boeing that they have to wait until a new engine design comes out to go ahead with the replacement for the B737. I hear around numbers that this is something like 10 years away.

Question: How long until there is a suitable replacement for the CF34s, and how difficult would it be for Embraer to upgrade the engine choice for the E-jets? I would think some of the current customers wouldn't be very happy as they got the "old" engine. . . if not a drop in resale value.

I'm interested in how you guys see this.
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EMBQA
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RE: Question About E-jets Engine Choice

Mon Mar 12, 2007 2:54 am

Quoting PPVRA (Thread starter):
So I have heard numerous times that Embraer wanted a more efficient engine for the E-jets than the CF34s

I've been with the E-jet program since nearly the beginning and that is news to me...
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PPVRA
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RE: Question About E-jets Engine Choice

Mon Mar 12, 2007 3:00 am

Quoting EMBQA (Reply 1):

I've been with the E-jet program since nearly the beginning and that is news to me...

Really? Hmm. . . must be another A.net rumor. . .

Regardless, the new engines coming up seem to be a whole new breed, super-efficient, bleed-less, etc. What are the prospects of converting to such engine once available?
"If goods do not cross borders, soldiers will" - Frederic Bastiat
 
mrocktor
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RE: Question About E-jets Engine Choice

Mon Mar 12, 2007 10:54 pm

Quoting PPVRA (Reply 2):
Regardless, the new engines coming up seem to be a whole new breed, super-efficient, bleed-less, etc. What are the prospects of converting to such engine once available?

I would say it depends primarily on the "up to dateness" of the rest of the airframe at the time these new engines become available. Re-engining an aircraft is a very complex issue, when you bring system interfaces into the mix, as would be required for installing a bleed-less engine on a bleed using airframe, we are talking major re-design.

If the airframe is still technologically up to date, it is conceivable that the conversion could be justified. If there is a prospect of significantly improving the aircraft, a clean sheet design is probably going to be the best option (since you are already messing with almost everything on the plane).

For the E-jets, if a new engine were available today and a competitor using it were on the horizon, with a huge operating cost advantage, I could see it happening. If this new engine appears on the market in 10 years, not a chance.
 
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Jetlagged
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RE: Question About E-jets Engine Choice

Tue Mar 13, 2007 1:03 am

Airbus seem to have come to the same conclusion over the A320 family.

Quoting PPVRA (Thread starter):
Today, we hear from Boeing that they have to wait until a new engine design comes out to go ahead with the replacement for the B737. I hear around numbers that this is something like 10 years away.

There wouldn't be a lot of point in launching a 737 replacement without significant gains in engine efficiency. The 787 is using technology more than 20 years newer than available for the 767 it replaces.

The same logic applies to Embraer. As for customers who got the "old" engine being unhappy, why? You have to factor in the costs of upgrading to the "new" engine, and presumably the "old" engine is still economical to run. I can't remember too many times where a new engine was offered for old in a buy back scheme. The 757 with RB211-535E4 engines comes to mind, but no others I'm aware of. In that case I think most operators kept the -535C engined aircraft they had.
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PPVRA
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RE: Question About E-jets Engine Choice

Tue Mar 13, 2007 10:50 am

Thanks for the info, guys. I guess that's just not likely to happen then.

A follow up question: Would it be viable to design an aircraft, from scratch, that has the flexibility to switch engine makers/models? Perhaps go beyond the engines and offer airlines the chance to further customize their own aircraft to a greater extent, from engine choice to avionics, and perhaps even other cabin system and IFE (the latter one is up to the airlines already, correct?). All this not just off the assembly line, but anytime during the life of the aircraft.

Sounds kinda expensive to me, but for example, if upgrading to a different engine wasn't as expensive, perhaps AA would have gone ahead with the MD80 re-engineing program we've been discussing here in A.net.
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mrocktor
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RE: Question About E-jets Engine Choice

Tue Mar 13, 2007 10:26 pm

Quoting PPVRA (Reply 5):
Would it be viable to design an aircraft, from scratch, that has the flexibility to switch engine makers/models?

That would be wonderful for the customer, no doubt! Can you imagine if all the 767 operators could just switch to GEnx engines and instantly gain 10-15% efficiency? That would be an incredible capability.

Unfortunately it is also not viable for a series of reasons, some of which are:

1. Airworthiness Regulation: This is the big one really. When an aircraft is certified, it is certified with a specific engine - extensive testing is performed that is extremely dependent on the particular characteristics of a given engine. Aside from performance (TO field length, climb, go around, range, landing field length) many other certification issues are hugely dependent on the engine (VMC, VMCg, internal noise, external noise, icing susceptibility, pressurization performance in case of bleed operated systems etc.). Approving a new engine requires showing compliance to all applicable regulation when using the new engine, which is expensive.

2. System integration: In most aircraft, the engines provide thrust, provide electrical power, provide hydraulic power and provide bleed air to systems. Integrating multiple different powerplants into all the systems that depend on them is a very tough task. Different engines will have different, spool up/down times, N2, will have different parameter thresholds (ITT, N1, N2, oil pressure), will probably communicate different data using different formats (they have, presumably, different FADECs). It is possible to provide a "standard engine interface", no doubt, but it is a huge task. Also, you depend on the engine makers actually building future engines to fit your interface (which may not be even possible, such as when the new engine is bleed-less and your standard interface uses bleed air).

3. Type rating: Assuming the manufacturer could approve several engines for use with the airframe and design a plane that could use them interchangeably, there remains the issue of type rating. There could come a point where different engines are so different in performance or in operating procedures that the different installations could not share a type rating.

I'm sure that there are many other factors that affect this issue. Keeping all that in mind, the 787's capability to interchangeably use two engine types is quite an accomplishment.
 
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Jetlagged
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RE: Question About E-jets Engine Choice

Wed Mar 14, 2007 5:57 am

Not to mention the high cost of the engines themselves. They are a significant part of the whole aircraft cost, so it would not make economic sense to change them simply to save a few cents here and there on fuel. The finance deal arranged with the engine manufacturer can sometimes swing the aircraft purchase decision.
The glass isn't half empty, or half full, it's twice as big as it needs to be.
 
Dougloid
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RE: Question About E-jets Engine Choice

Wed Mar 14, 2007 7:17 am

Well, the CF34 is a derivative of the TF34 military engine and it is a mighty expensive piece of hardware, pound for pound. Getting it on a civil airframe was something of a mad dash to save the Canadair Challenger program, because the ALF502 nearly sunk the entire program....
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PPVRA
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RE: Question About E-jets Engine Choice

Fri Mar 23, 2007 11:01 am

Quoting Mrocktor (Reply 6):
Keeping all that in mind, the 787's capability to interchangeably use two engine types is quite an accomplishment.

Does the 787 accomplish that by using a "standard engine interface" (same thing as a standard FADEC, right?) as you mentioned?

Thanks for the replies!
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mrocktor
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RE: Question About E-jets Engine Choice

Fri Mar 23, 2007 11:51 pm

Quoting PPVRA (Reply 9):
Does the 787 accomplish that by using a "standard engine interface"

As far as I know, the mechanical attachments to the pylon are the same (and presumably the system connections are as well - electric power cables, hydaulics etc.). Not sure how the software and control issues are handled, either they have code on the aircraft side that can detect the type of engine or they have to load the appropriate software when the engine is changed...

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