AFC you are right. That is understandable like in the case of United Airlines. Their fleet of 767 is PW equipped because almost all of their current planes use PW engines except the 737-300, 500. (I am not sure if they have -400) Airbus 320 too uses an engine built with PW cooperation (V2500)
How does engine comonality come into play with American Airlines? Their 767's are GE equiped, 757's are RR and now their 777's are RR equiped. Of course, they used 767's long time before 777's came in and their DC10 and MD11 used GE engines. Still, what I am trying to show is that there is no forced engine commonality in this airline. They use all Engine manufactures now. Why would not they opt for a RR engine on their 767 fleet?
There must be some other reason.
Radar Contact Terminated, Squawk VFR