Airline engine fixed TBO?
 

When I worked in the commercial engine business some decades ago, most of the world had transitioned from fixed Time Between Overhaul limits to on-condition maintenance - based on parameter trend monitoring or cyclic count limits for highly stressed "prime reliable" parts.

But in some jurisdictions the old TBO rules (from piston engine days) still applied - especially on newly-introduced models/types in that jurisdiction. (I'm thinking of Japan in particular.) Who knows if any countries still apply mandatory TBOs?