Originally Posted by
Three Wire
EPR was invented by and is proprietary to RR. When PW made a licence agreement with RR to produce engines in USA, the EPR technology was included.
hence why GE does not use EPR.
This may be part of the historical reason in the first place - however as a patent is only good for 20 years this would not have been a cause for the non usage of EPR by GE for the last 40+ years.