With Turbofans/ Jets. What is a modular engine ?

Answer 1

What it means, basically, is that sections of the engine-turbine, combustion section, accessories etc.-are assembled as a unit ("module") and is designed to be easily replaced as a unit without disturbing the rest of the engine. On older engines, something as simple as a turbine change required a time-consuming process of disassembly, inspection, keeping track of hundreds of parts, reassembly, precise measurements, and testing which may involve many hours of troubleshooting & adjustments.

Answer 2

Are you referring to the engine on the 787? The power section, or propulsor as GE calls it, and the fan section are separate. Typically the propulsor needs maintenance more often, but they have to dismount and transport the whole big heavy engine to service the relatively small power section. On the GEnx you can dismount the propulsor alone and swap in a replacement without having to remove the entire engine from the plane. Take a look at the GEnx info on Wikipedia or