Turbine engines could go on for serioulsy extended periods of time. It very much depends on the engine model. Turbine engines like the PW100 turboprop series are designed for short hop flights, usually less than 1 hour, although on some aircraft [F50 MPA, 2x PW127B engines], they can do missions of over 10 hrs. In normal airliner use, these engine can do upto 4000-8000 flights without any shop maintenance, only the normal line maintenance checks required. I have seen PW118B engines that ran for 16,000 hrs/20,000 flights with only one Hot Section shop visit!
Large turbofan engines like CF6 are more designed for long range flights, which usually have a duration of 10 - 15 hrs per flight. I believe these engines can be run for 10,000 - 20,000 hrs on wing [or about 1500 - 2500 flights]. GE
[also Rollce-Royce] built land based engine based on their big turbofan turbomachinery. These engines are used in electricity gerating power plants, gas pumping stations, ships etc. and can be run continueously for over 20,000 hrs [there are 8670 hrs in one year - 2004 btw has 8694 hrs . . . ].
Keep in mind that max power output determines the life of an turbine engine. De-rating an engine by 10-15% will double engine life. Or in other words, the last 10-15% of the engine power range is responsible for 50-75% of engine wear. Reducing the amount of time the engine runs at this level [like long range cruise], will seriously increase engine life. If the engine lubrications systems are slightly modified, most aircraft turbine engines can be run for over 20,000 hrs continueos operation at reduced power level.
Once a turbine engine has been shut down, usually it needs to cool down before restarting, depending on power levels prior to shut down. Cooling down can be done at ground idle power setting. Turbine engines generally don't like to be shut down straight from take-off power. They also require warming up before slamming to take-off power.
Hope this helps.
. Indeed this is more for tech/ops.
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