Speaking of longevity of the CFM-56 engines, am I correct in my memory that I've read somewhere that a CFM-56 engine is responsible for operating the highest number of hours without being removed for attention? I can't remember the exact figure, so I won't guess, but it was astonishing, even to a layperson
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15 Jun 1997: A CFM56-3 engine powering a Boeing 737-500 with Braathens S.A.F.E. reached 19,855 cycles without a single shop visit, setting a new world's record for time on wing. The previous record of 19,841 cycles was held by a CFM56-3 engine in service with Southwest Airlines. The CFM56-3C1 engine, which entered Braathens' fleet in October 1991, was removed after nearly six years of service due to life-limited parts in the core.
Halfway down this page:
http://www.b737.org.uk/737classic.htm