In 2014 PZL Mielec obtained an EASA Type Certificate extension for the PZL M28 05 airplane for flight into icing conditions and this has been validated by the FAA. Thus, a project that lasted four years was finished successfully. During this period, activities consisted of icing analyses, wind tunnel tests in the NASA Glenn Research Center Icing Research Tunnel, and natural icing flight tests, artificial icing flight tests, flight tests with simulated ice shapes, and calibration tests. Flights in measured natural icing conditions began during the spring of 2009 and certification flight tests were performed in 2012. The natural icing test flights, apart one flight in the USA, were performed in Poland in the Mielec area. The final test campaign can be divided into two phases: (1) March -April flight tests campaign; and (2) November - December flight test campaign, the latter after introducing some design changes in airframe ice protection system.