Originally Posted by
Lyman
Covered extensively in the thread, search there. Briefly, "A three spool is a three spool"
Oversimplification. If this were the case then the entire Trent series could be grandfathered from the RB211. We know this isn't the case and that each series of the Trent had to undergo most if not all of the certification tests individually.
See also why the 700, with blade stator clash, contained the IPT in 'Edelweiss' ex Miami.
The 900 substituted a Stator 'platform', the IPT oversped, and the Islanders collected Titanium. same certificate....
The overriding feature of the Trent series was to minimise the requirement for variable stators - there's a nice overview here :
Rolls-Royce Engines: Trent
All new and derived designs have kinks that require ironing out - this is accepted fact.
Actually, the failures are quite similar in nature. 100k thrust cannot be gained by inventing a brand new platform. There was more room in GE's device, but that does not exonerate them from shortcuts to the grail.
None of this is specific to the Trent series though - it's just a feature of progress in jet engine design. The "two-spool vs. three-spool" argument is a fallacy as unnecessary as the old "A vs. B" chestnut.
For example, a two-spool CF6-80 notoriously let go during a test at LAX:
FAA to Tighten Inspections on Some GE Jet Engines - Los Angeles Times