Jetdoctor From United Kingdom, joined Aug 2001, 257 posts, RR: 0
Reply 1, posted (11 years 5 months 2 days 2 hours ago) and read 2204 times:
I can broadly answer #3 for you.
An airlines selection of engine can depend on many things, but usually comes down to money, fuel economy and reliability.
An airline buys/leases the airframe, and then can bargain with the "Big 3" as to why they should purchase/lease their engines. Certain performance guarantees can be made, or quantity discounts if say the airline is buying 20 aircraft (40 engines plus spares), or it can come down to product support packages too.
All in all an airline wants a cheap engine that will run forever and give it the most miles to the gallon.
Hope this sorta answers #3 for ya
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