What is the effect of the Freezing Point Depressant (FPD) fluid residue on engine fan or compressor blades?

The residue left by Freezing Point Depressant (FPD) fluid on engine fan or compressor blades can significantly impact engine performance. When the FPD fluid residue accumulates on these components, it alters their aerodynamic properties. This alteration can disrupt the smooth flow of air through the engine, leading to a reduction in efficiency and performance.

As the airflow becomes disturbed, the engine may experience situations where the compressor cannot maintain the necessary airflow, potentially leading to compressor stalls or surges. A compressor stall occurs when the airflow is disrupted to a point where the compressor can no longer efficiently compress the incoming air, while a surge refers to an abrupt reverse flow of air within the engine that can also cause operational issues. These effects collectively reduce the overall thrust and power output of the engine, thus demonstrating how the presence of FPD residue can negatively impact engine operation.