I guess there's no common european regulation right?
I'm referring to ownership and maintenance,permit to fly certificates and so on.
I'll just give an example:
I've seen two airplanes for sale,one in france,one in the UK;
the first one is registered F and the other in Germany.
I dont think they are IFR certified (I'm still waiting to get a reply from the seller),but once I buy the plane,can I change the country registration (i.e. bring it from F to D registration?).
let's say the plane is NOT IFR certified,can I add the instruments myself (through a maintenance organization of course)and then have it re-certified?
if an aircraft has a certificate of airworthiness,is it possible to change it into a permit to fly so that I can do the basic maintenance?is it worthy or useless?
Most European countries, only something with a CofA can fly IFR, regardless of instrument fit. That may be changing shortly in the UK, and I think that there are a few countries where you already can, but a small number.
If it does have an EASA CofA switching register is pretty straightforward. A national CofA may be possible, may not. If it doesn't have a CofA, it's nearly impossible.
There is a cross-European sub-CofA document called an "EASA Permit to Fly", but not many aeroplanes have it, and fewer people understand what to do with it.
G