Every year, Europa edits a list of airlines banned within the EU, because these companies are not secure and don't provide a correct maintenance level of their planes. You can find out more here: http://ec.europa.eu/transport/air-ban/list_en.htm
The only problem is that Europa's list is complicated to consult. I have found a list of the blacklisted airlines on Air Valid, an independent agent: blacklisted airlines. This is a pretty useful list for those who are traveling outside Europe.