EGBJ
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Engine Choice

Mon Jan 22, 2007 11:58 pm

After looking at the current 787 orders I noticed there is a pretty even split between carriers choice of engine (170 for GE and 123 for RR according to Wiki).

My question is, what influences a carrier's choice of engine?? I presume it depends on the planned ops for the aircraft in the respective airline fleet's, but in what way??

Thanks,
Rich
 
Rick767
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RE: Engine Choice

Tue Jan 23, 2007 12:13 am

Engine choice is a very big factor in an airlines decision making process when ordering new aircraft. It is almost as important a decision as the aircraft choice itself, and competition between the powerplant manufacturers is often just as fierce as between aircraft manufacturers.

Rightly so of course, as these are by far the most expensive components of the aircraft.

When it comes to choosing a particular powerplant for a new aircraft many factors will come into account like cost, performance (particularly for airlines needing good hot-and-high capabilites), maintenance arrangements and commonality.

An airline with Rolls Royce engines in its fleet already, with engineers trained on those engines, will be inclined to choose Rolls Royce in a future order because it will minimise re-training and possibly accept some identical spare parts, etc...

A higher thrust engine may be good for hot-and-high performance, but this is usually at the expense of more weight and poorer fuel consumption, so not worth it for an airline which will rarely utilise the benefit.

The other big issue is politics, it may be preferable for a British carrier to support British jobs and industry by choosing Rolls Royce engines, for example.

In essence there is a lot that goes into it, but that gives you an idea.
I used to love the smell of Jet-A in the morning...
 
EGBJ
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RE: Engine Choice

Tue Jan 23, 2007 12:47 am

Thanks a lot for the reply Rick767  Smile

What about leasing compainies?? If they dont know where their planes are going to find work, how do they know what powerplants to choose.

Rich
 
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lightsaber
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RE: Engine Choice

Tue Jan 23, 2007 1:05 am

The 787 is unique amoung airliners. Why? If an airlines chooses the wrong engine for their mission, they'll be able to switch.

There is some variation with planned ops on the 787 engine selection.

The Trent 1000 has a lower climb fuel burn. Thus, operators on the shorter end of the range spectrum (say < 5000nm) will save buying the Trents.

GE is promising 2% lower fuel burn at cruise. If this is delivered (and RR doesn't match them), they'll have an advantage on the orders for the airlines on the longest haul missions.

However, if either engine maker "drops the ball," the airlines will just return the airframes to the leasing companies. Then the leasing companies will swap the engines/nacelles and repackage the plane for another airline.

I'm going to be very interested to follow the resale values of these engines. Its going to scream who has the better powerplant.  spin 

Both are great designs. If I knew which would win, I'd tell you. Right now its either vendors sales campaign to lose.  Wink

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N231YE
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RE: Engine Choice

Tue Jan 23, 2007 1:23 am

Question...what happened to Pratt & Whitney?
 
GQfluffy
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RE: Engine Choice

Tue Jan 23, 2007 2:18 am

Quoting N231YE (Reply 4):
Question...what happened to Pratt & Whitney?

The 777....
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jben
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RE: Engine Choice

Tue Jan 23, 2007 8:09 am

Yeah, That PW4098 sold like hotcakes... and with it's amazing fuel economy.

:ducks:

Seriously though, PW has had a series of problems and miscalculations. On the 787 both GE and RR offered advanced versions of existing designs, whereas PW wanted to do an all new design. Boeing decided that the PW plan had too much risk, and went with RR and GE. Also, how many new civil aircraft have a PW on them? They're not on the 787, 747-8, A350... and they're only on the A380 as part of the Engine Alliance team with GE.

Simply, Rolls Royce and General Electric have done a superb job in the civilian market. PW seems to be focusing alot more on their military customers, with the F119 for the F-22 and the F135 for the F-35. Having said that, if PW can produce their GTF... that will rocket them back as the fuel economy benefits of the GTF are very hard to deny.

On the 787, I can't wait to find out who QF chooses. I hope Rolls Royce gets the deal!
 
qutaiba
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RE: Engine Choice

Sat Jan 27, 2007 9:47 pm

1. Payload Range Performance.

2. Performance guarantees.

3. Durability, i.e. on wing time, particularly the high pressure turbine operating hours projections).

5. high pressure system hard time (and other components as well).

4. Maintenance cost guarantees.

5. Fuel consumption.

6. manufacturers concessions to keep the engine ownership and maintenance costs projections at levels acceptable to the airline (and may also be used for comaprisons).

7. The golden rule; the boss is always right.
When the tide comes in, all ships will rise
 
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aerorobnz
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RE: Engine Choice

Sun Apr 10, 2016 4:12 am

I have heard a rumour that RR 787 engines are failing after 5000 hours and airlines worldwide are currently swapping out engines to make sure they don't have a double engine failure as they tick over number of hours until a directive from Boeing is issued..Has anyone else heard anything about this?
Flown to 147 Airports in 62 Countries on 83 Operators and counting. Wanderlust is like Syphilis, once you have the itch it's too late for treatment.
 
Dalmd88
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RE: Engine Choice

Sun Apr 10, 2016 1:42 pm

Quoting aerorobnz (Reply 8):
I have heard a rumour that RR 787 engines are failing after 5000 hours and airlines worldwide are currently swapping out engines to make sure they don't have a double engine failure as they tick over number of hours until a directive from Boeing is issued..Has anyone else heard anything about this?

I don't know much about the failure rate of the RR on the 787, but it is very common practice on a new airplane delivery to swap out one of the new engines for a mid life engine to stagger the life. We do it at DL on a lot of deliveries.
 
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xms3200
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RE: Engine Choice

Sun Apr 10, 2016 2:10 pm

Boeing was advertising a "common" pylon for the Rolls and GE engines when they were designing the 787 whereby a leasing company could simply remove a Rolls Royce engine from a returned 787 and install a GE engine and vice-versa without any modifications for the next new customer for the airplane. I do not know if this "common pylon" concept made its way to final manufacturing. Any one with Boeing insight could please chime in.
 
Okie
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RE: Engine Choice

Sun Apr 10, 2016 3:48 pm

Quoting xms3200 (Reply 10):
I do not know if this "common pylon" concept made its way to final manufacturing

That was early in the design concept stage.
The problem was that the different engine manufacturers position of pumps, fuel connections, electrical made that too complicated to happen within the space of the engine cowls.
The common interface so to speak is at the wing to pylon join. Therefore the engines can be swapped brand for brand but the engine pylon has to be changed as well.
Also there is differences in software between engine brands which can be changed in the field but throws out the concept of a GE on one wing and a RR on the other.

Okie

[Edited 2016-04-10 08:52:27]
 
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xms3200
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RE: Engine Choice

Sun Apr 10, 2016 10:52 pm

If the pylon has to be changed to switch between GE & Rolls Royce in the 787, that would be the same case as the 747-200, where in the late 1990's I believe, Atlas Air contracted Boeing to replace the original Pratt & Whitney JT9D engines with the GE CF6-50E2. Seems like with a pylon replacement, you can get any engine of choice on Boeing's at least.
 
prebennorholm
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RE: Engine Choice

Mon Apr 11, 2016 12:57 am

Quoting Jben (Reply 6):
Also, how many new civil aircraft have a PW on them? They're not on the 787, 747-8, A350... and they're only on the A380 as part of the Engine Alliance team with GE.

...and a 49.5% stake in the IAE V2500 program, 5500 engines produced, and counting until their GTF takes over.

By value PW produces 61% of the V2500 engine.
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Jetlagged
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RE: Engine Choice

Mon Apr 11, 2016 4:45 pm

Quoting Qutaiba (Reply 7):
1. Payload Range Performance.

2. Performance guarantees.

3. Durability, i.e. on wing time, particularly the high pressure turbine operating hours projections).

5. high pressure system hard time (and other components as well).

4. Maintenance cost guarantees.

5. Fuel consumption.

6. manufacturers concessions to keep the engine ownership and maintenance costs projections at levels acceptable to the airline (and may also be used for comaprisons).

7. The golden rule; the boss is always right.

All these technical assessments are very important, but an operator might still order the less economic engine if the finance terms were more favourable. Maybe that comes under point 7.  
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lightsaber
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RE: Engine Choice

Mon Apr 25, 2016 4:44 am

Quoting Jetlagged (Reply 14):
All these technical assessments are very important, but an operator might still order the less economic engine if the finance terms were more favourable. Maybe that comes under point 7.

If the finance terms are more favorable, doesn't that make it the more economic engine?


With the 787, mission length changes which engine is optimal. Either way, great airframes/engine combo.


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aviatorcraig
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RE: Engine Choice

Tue Apr 26, 2016 3:45 pm

Quoting aerorobnz (Reply 8):
I have heard a rumour that RR 787 engines are failing after 5000 hours and airlines worldwide are currently swapping out engines to make sure they don't have a double engine failure as they tick over number of hours until a directive from Boeing is issued..Has anyone else heard anything about this?

Strange that you chose to bump a nine year old thread to ask this question!

If these engines needed to be swapped out to avoid a double engine failure I would expect the worlds regulating authorities to be all over this - and they are not. Does anyone have any figures for 787 engine on-wing times achieved?
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Stitch
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RE: Engine Choice

Tue Apr 26, 2016 4:11 pm

Quoting aviatorcraig (Reply 16):
If these engines needed to be swapped out to avoid a double engine failure I would expect the worlds regulating authorities to be all over this - and they are not. Does anyone have any figures for 787 engine on-wing times achieved?

It's actually GEnx engines with PiP2 that are now under an FAA directive to be swapped out due to an issue where ice accumulation on the fan blades can cause the blade to drift forward and strike the forward edge of the cowling.

There is a thread about it in CivAv: FAA New AD Against B787 - GenX Icing (by budalb Apr 22 2016 in Civil Aviation)
 
Okie
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RE: Engine Choice

Tue Apr 26, 2016 7:51 pm

Quoting Lightsaber (Reply 3):
However, if either engine maker "drops the ball," the airlines will just return the airframes to the leasing companies. Then the leasing companies will swap the engines/nacelles and repackage the plane for another airline.

I'm going to be very interested to follow the resale values of these engines. Its going to scream who has the better powerplant.

Interesting indeed.
Considering that normally you would think of the operator returning 5 or more frames to the leaser. I am not sure where you would find 10 or more of the other manufacturers engines new or used if the new client wants to change engines.

The cost could get pretty prohibitive if the leaser would have to purchase a set of new engines and pylons on a used plane to lease or sell a used aircraft with a lot of cycles.
Not sure exactly how power by the hour would work out either, I would expect the original engine supplier would be making some pretty sweetheart deals rather than putting a used engine on the shelf.

Okie
 
LH707330
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RE: Engine Choice

Sun May 08, 2016 6:26 pm

Quoting lightsaber (Reply 15):
With the 787, mission length changes which engine is optimal. Either way, great airframes/engine combo.

This can be generalized to triple-vs-twin spools in general, IIRC the 380 has a similar tradeoff.

The CFM and IAE on the 320s have a similar tradeoff, the IAE is better at longer range because its two-stage HPT is more efficient, but the maintenance costs are higher, do the CFM does better on short trips with more cycles. I think this is part of the reason that B6 wen IAE on their 320s (they were also annoyed at Boeing/CFM for taking them for granted).
 
Viscount724
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RE: Engine Choice

Mon May 09, 2016 3:38 am

Quoting xms3200 (Reply 12):
If the pylon has to be changed to switch between GE & Rolls Royce in the 787, that would be the same case as the 747-200, where in the late 1990's I believe, Atlas Air contracted Boeing to replace the original Pratt & Whitney JT9D engines with the GE CF6-50E2.

I believe Atlas Air did that only on a couple of 742s. I can't recall any other airlines switching engines on 747s.

The #1 prototype 777-200 was also re-engined from PW to RR when it was refurbished and sold to CX after several years with Boeing. It's still in service almost 22 years after it made the 777's first flight June 12, 1994.


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