I have the good fortune to be borne aloft by RR engines.As well as having external fire sensors these engines have sensors in the core of the engine which give early warning of overheat in the critical area of the engine which enables shutdown before serious damage or fire occurs.I`m not sure if the CFM56 is fitted with these.I believe there have been CFM56 failures in the past which have been difficult to diagnose with at least one leading to an accident.. .Glad to be flying RR!