Most of our engines from the PW120's to the JT8's have cycled or houred out.
The PW120 is on condition however the HP
disk and Cover plates all have a 15000 cycle life. This usually coincides with an HSI. The rest of the rotating parts have a 30 000 cycle life.
All we do is oil filters( both scavenge and main) every 500 hours, and nozzles and flow divider at 1500 hours and a full engine boroscope at 1500 hours.
It can be hard timed for some operators then it has an 8000 hour life.
On the JT8 the life of the rotationg parts in most cases are 30k hours and 20k cycles, except for the c1 which is 20k cycles and no hour life. Some of the other disk lives are lower depending on the the part number of the disk.
Plus the Jt8 has a 4year or 8 year calendar life from AD
2003-12-07 on the HPC( stages 7-12) for a corrosion inspection. It gets a 4 year depending on the C-9 part number.
darts are on a 7000 hour TBO. They require more work and usually a repair at the half way mark.
Other than that as long as it does not cycle or hour out it keeps going unlit it comes appart in flight... [hyper]
Sometimes all you can do is look them in the eye and ask " how much did your mom drink when she was pregnant with you?"