What are the different steps to certify a new aircraft in Europe? I know that to be allowed to fly an aircraft has to be certified by an agency and that this one is not the same for European or American (for instance) aircraft. What are the different steps that an aircraft designed to fly in Europe has to go through in order to be certified? Proof on the paper of some features? Ground tests (which one)? Flight tests (which one)?
The EASA certification requirements are all publicly available online. Actually proving that an aircraft meets those criteria will certainly include all the steps you mentioned although exactly what happens probably depends a lot on the specific aircraft and manufacturer.