Originally Posted by
tdracer
Engines last at long longer than you might think - obviously overhauled multiple times.
"First Run" engines generally go between 10,000 and 20,000 hours before getting overhauled the first time (assuming they don't get lots of short cycles - cycles are even harder an engines than they are on airframes). Some real long haul engines can go 30,000 hours first run, due to the low cycle counts. Overhauled engines don't get that close to 'zero time', so their time on wing before the next overhaul is considerably shorter than first run engines - often as little as half as long. Obviously the burner and high turbine take the brunt of the abuse, but compressor blades wear and abrade and even fan blades benefit from the occasional TLC. I recall seeing engines that were well over 60,000 hours since new, obviously overhauled several times. At some point, it becomes a question of what constitutes the original engine - rotating components are often life-limited parts, and must be replaced (and the original scrapped) after so many cycles. Further, components get swapped between engines - particularly some of the newer modular designs, where instead of rebuilding the engine, they simply swap out a module - for example a turbine - with one that's been overhauled and return the engine to service. After a while it becomes like that old farmer's axe - the handle has been replaced 4 times, and the axe head five times, but it's still the old farmer's axe :}
even more off topic:
my older brother bought a motorcycle when he was 16, and I got it when he left the house at 18, modified it a bit, and passed it onto my little brother 2 years later. He modified it more, drove it for another few years, I crashed and repaired it, and when he sold it we found out the only original parts were the fuel tank and the front fender....