Now you’ve asked something!! Engines these days are pretty good in the field of reliability. There are still engines powering aircraft which have remained attached to the wing since they were fitted by the manufacturer. And I’m not talking about an aircraft which was built last week!! Todays engines typically utilise a modular construction, so if some parts go wrong, you can replace the part of the engine easily. Also, engines have built in features for makintainers, so the engine can be inspected by engineers without the engine having to be removed from the aircraft.