And just an innocent question, what do you do with the faulty module?
A module, as I understand is compartmentalization of parts..
So in engines where parts are replaced like the Russian engines, the mechanics try to identify the problem and then replace the faulty parts, Time consuming but in a way cheaper,
In modular way, the entire module is replaced, Thus parts which are otherwise fine, or still have say more than half service life would be replaced. These parts (depending on the Standard operating procedure ) would be recycled. Thus with modular engine, the advantage is higher availability. as there is no real need to identify the faulty part, just replace the module. But this will end up being expensive if some of the parts are not recycled, and if they are then it can in a way be problematic for the engine (till the engine is overhauled). But on other hand, replacing faulty parts will be time consuming but cheaper and could be problematic till time of overhaul.
Russian engines are meant to be robust, and made cheaper, In case there is problem with engine, they replace the entire engine and then the faulty engine is repaired by the mechanics at their own sweet time.
Thus the Russian engine is designed to be cheap and robust and during the lifetime of the plane, the total cost spent on the engine does in a way become similar or cheaper than the total cost spent on french engine due to expensive parts.
