The Boeing vs. Airbus debate seems never-ending. However, I've never encountered a powerplant debate and am really not too familiar with powerplants, except that the major suppliers of powerplants are Pratt and Whitney, Rolls-Royce, and GE, both serving Airbus and Boeing.

Here are my questions:
* Why do the aircraft manufacturers even give powerplant options? Doesn't that increase complexity with regards to integration with the aircraft systems? Looking at the A333 and B777, there are 3 options, with maximum thrust differences being really negligible. Why go with one over the other?
* With regards to powerplants, does the aircraft operator directly work with the powerplant manufacturer in terms of "warranties" and "recalls?" Or is the aircraft manufacturer the intermediary?
* When pilots are certified to fly a certain aircraft type, are they also "stuck" to a specific powerplant? What if the aircraft operator decides to buy more of the same aircraft type but with different a powerplant manufacturer? Is there additional training required for the pilots?

Moderator, feel free to move to Airliners.net.

Hey this reply is completely irrelevant, but I just needed to...

LOL

Pilots who are rated on one type can fly it, regardless of what kind of engine is attached. I do not know of any exceptions to this.

In terms of why an airline may choose different powerplants, one reason is fleet commonality. BA had 747 engines bolted to their 767s (some of the few such examples in the world) because they have so many 747s that it significantly reduced maintenance costs. Another option might be that a particular engine manufacturer might give discounts to the airline as well. It's a pricing game, of course.

There is usually a very short differences training required, but different engine types share the same general type rating for pilots.

Engineering type rating on the other hand can be entirely different for the same aircraft type with different engines.

someone who works at an airline managing the powerplant contracts said it is also to do with managing hours on the engines so that even though they might be swapped on and off aircraft - at the end of a lease period the airframe and the engine have the same number of hours on them.

Many potential reasons. Operators sometimes simply prefer one manufacturer over another sometimes. Commonality. Price at the time of purchase. Price over time. On occasion, it's as simple as who the operator is: they might be unable to get export permission for one engine, but it not be a question on another.

country of origin of engine plays a major role. keep britain happy, etc.

It is the same for plane, all political.

DL purchase of 40 AB, did anyone thought that would happen if AB did not have a manufacturing in the US South? The AB they inherited from NW, would that happen if not for the NW/KL relationship?

Low Boeing presence in China when the aviation industry was starting, did Sina-US realtionship played any role?

It's a little dated now, but the book "The Sporty Game" by John Newhouse (1982) gives some good insight into the sales competitions for both airplanes and engines. Till I read it I never realized that the engine selection process was as competitive as the airframe selection.

Selection considerations can include any/all of the ones listed by the other posters, and political considerations can certainly be equal to or outweigh economic and/or operational reasons.

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The engines are more valuable than the airplane in many cases. (especially on older models).
So really, if you want to look at it another way...an airline is buying a set of engines with options as to what airframe they want attached to them.

With regards to new a/c purchases, every manufacturer has its selling points. For example, on the 757, the Pratt 2000 boasted a 2% better fuel burn than the Rolls-Royce 535. The 535 proved to be a much more reliable and less-expensive on a cost-per-hour engine, in spite of the fuel burn....so much so that AA parked their Pratt-powered 757s they inherited from TWA....and then sold them to Delta.
Delta, having a massive PW2000 maintenance machine already in-place, can operate Pratt 757s and make money. AA could not.

Is it possible to just replace the engines on an existing aircraft? If it is, then I take it AA figured that it was not worth the extra cost of buying a new set of engines.

Maintenance switches engines on aircraft often when repairs are needed. However, one probably wouldn't want to fly with unmatched engines.

In the TWA/AA/DL case, AA might have been better off financially to sell whole airplanes to DL versus buying new engines and putting them on the frames, then trying to dispose of the unwanted excess engines.