What is the actual numerical reliability statistics of the modern, large-aircraft, commercial turbofan engines available today?
e.g. How many running hours can we expect a failure after? Are there empirical or projected MTBF statistics?
How is credible MTBF established for a new engine model?
Is there a significant difference in the failure rate between engine models or manufacturers?
I was motivated to ask by this snippet on another answer on SE Aviation:
In the days of the 747 regulations required at least 3 engines if you ventured more than 60 mniutes of flying time away from a suitable diversion airport (in case the second one also failed). However as reliability of engines increased this got extended with ETOPS certificates.
How rapidly has engine reliability improved? Do we have a time trend of reliability numbers?