Can I change the engine in my plane
 

I'm looking for some help/advice.

I am the owner of a Robin ATL, small single engine light aircraft, which is (under)powered by a JPX 4T60 engine (basically a VW aero derivative engine). There is an alternative version flying with a Limbach engine, but both are slightly under powered.

So I was thinking about replacing the old JPX, when it's due for replacement, with perhaps a Rotax, or other such equivilant. On the face of it, the Rotax is about 19 kg's lighter than the JPX, so there are no significant changes in the CG.

The plane is a French registered aircraft, so I am not sure how easy/difficult the French would be in allowing such a change. Mind you, if you believed that another CAA authority might be more open minded, let me know...but I suspect that this might be something driven by EASA.

Anyway, is it within a plane owners rights to change one certified engine out with another, or am I limited to overhauling my JPX/replacing with an already approved Limbach variant?

Any help or advice you could give me would be most welcome.

Thanks

You have given yourself the answer ..

with an already approved Limbach variant

You just need to get the approvals done for the desired option and then you have the option. I have no idea what the French might mandate but expect to look at powers and torques, gyroscopic loads, CG, oil consumption, etc.

Potentially, be prepared to put your hand in your pocket for substantial dollars (francs ?)