The US Navy became aware of a Russian erosion-resistant compressor coating in 1991. The coating was being applied to compressor airfoils on the TV2-117 engine (MI-8 helicopter). Performance data obtained from the Russian coating company showed greatly improved erosion resistance, leading to better engine performance and longer time-on-wing. A proposal was sent to the Foreign Comparative Testing (FCT) office to evaluate the coating for US Navy engines operating in sandy environments. The project was approved and funded in 1997. It was determined that the high-speed erosion chamber at the University of Cincinnati would provide the optimum testing environment for the program. The test articles consisted of a bare blade and a coated blade. Testing conditions required 10 micron silica sand impinging upon the blades at 700 feet per second (fps). Data was collected until the bare blade reached the chord reject criteria. Testing continued until the coated blade reached failure as well. It was found that the coating improved the overall blade life by 300–500%. A method was developed to measure the eroded blades at certain points to determine the real or “effective” chord at any point during the testing. This project demonstrated the need for innovative gauging techniques in order to understand the actual effects of erosion on compressor blades.

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