The first-stage high-pressure turbine blades in RAAF T-56 engines have a rejection rate which is unacceptably high. It has been revealed (1) that the current coating, a conventional nickel aluminide, has a greater than 60% rejection rate after 2000 hours. Consequently, a trial programme was established to assess the benefits of five alternative protective coatings and to determine which coatings, if any, could withstand up to 3000 engine operating hours. A previous report demonstrated the potential of platinum and platinum/rhodium modified aluminides after 1500 hours of engine operation. This report, after approximately 2000 hours of service, supports the previous recommendations that the precious metal aluminides offer superior resistance to hot corrosion than the conventional aluminides and chromium-modified aluminides. The inability of the silicon-modified aluminide to form an evenly distributed coating over the entire blade renders it unsuitable ... Protective coatings, Hot corrosion, Allison T56 engines, Gas turbine blades.