The European Commission is preparing to send Greece a stern warning concerning the country’s failure to adopt European Union standards regarding passenger aircraft maintenance, sources in Brussels told Kathimerini yesterday. The «reasoned opinion,» which is the last step before the Commission resorts to the ultimate measure of taking Greece to the European Court, is expected to be sent over the next few days. It will charge the government and the Greek Civil Aviation Authority (YPA) with breaking two-year-old pledges to adopt EU quality controls on aircraft maintenance units functioning in the country. These controls were first adopted in 1991. The US Federal Aviation Authority has repeatedly accused YPA of being unable to maintain satisfactory flight safety standards.