I'll post this question on its own thread since it didn't really fit in earlier.
How much commonality do jet engines of the same manufacturer have with each other?
We always hear on this forum people arguing that an airline that has PW powered jets in its fleet will power their newly ordered jets with PW as well, etc. because of commonality. How is this possible? Over the years, most of the reason that planes are more efficient today is because of great strides taken in powerplant technology. So, the question is, how similar is the CFM56 to the CF6 and GE90, all made by GE/Snecma, but at different time periods. To go further even, how similar are the CFM56-3 and CFM56-7 which are different time periods, and different power ratings?
Also, we hear on this forum much about how UA with its large PW powered fleet buys V2500 powered 320s because IAE, the makers of the V2500 has PW as a partner, and thus they have commonality with the other PW engines in the fleet. Similarly, we hear that BA with its large RR powered fleet buys V2500 powered 320s because IAE has RR as a partner, and thus they have commonality with the other RR engines. So, how can this be? How much commonality can an IAE engine have with both RR and PW at the same time? Can a mechanic trained on the V2500 work on a PW4000 and know what's going on? How about an RR Trent?
Any input would be much obliged. (Thanks in advance!)