Windmilling
Windmilling of TurboFan Engines can be a major problem.
CFM56-3 motor AMM says that if it has windmilled for more than 6 hours the engine must be replaced.
During the windmilling action the lubrication pumps with-in the lube unit turn into scavenge pumps removing oil from the oil tank and placing it into the engine sumps damaging the ail-oil seals.This is why some airlines fit engine fan straps to engines in ports where engineers do not provide 24 hour coverage.
From memory the CF6 and the CFM56-5 motors had more tolerance (think it was @8hrs)