Originally Posted by
amsm01
On a related subject prompted by the part lifetime docs posted by aerolearner in the initial reply: they contain cycle lifetimes for various elements within the turbine - spool, disk etc - but not the blades themselves. Therefore is it correct to understand these are not life-limited parts as such? I found this a bit surprising given they’ll be exposed to the same high centrifugal forces and heat or is this mitigated by the fact they’re inspected and x-rayed whereas the larger components listed in the doc can’t be?
Breaking a turbine blade is not a big deal - high vibes and a probable engine shutdown, but unlikely to threaten continued safe flight and landing. Bursting a turbine disk is an uncontained engine failure and potentially catastrophic (think Qantas 32) - hence the discs are life-limited parts.
The blades are removed and refurbished on a regular basis (although LP turbine blades are not that highly stressed compared to the HP blades) - but are not considered 'life limited' parts. Of course, turbine blades do get scrapped (and they do track hours and cycles to determine the refurbishment intervales), but as long as they pass inspection during refurbishment they can be re-used indefinitely.