Laboratory Testing of Aircraft Anti-Icing Fluid Rehydrated Gel Residues
Gel residues occur as the result of repeated anti-icing fluid application that leaves a powdery film upon dryout that, when rehydrated, can swell up to over 600 times its weight. When these gels collect on aircraft flight control surfaces in aerodynamically quiet areas and freeze, they give rise to reduced performance, increased stick force, slowed rotation and have caused jammed flight controls. Laboratory tests have been developed to simulate the gel formation by drying out fluids and rehydrating them. However, by their complex nature, much variation is seen between test results from different laboratories and the results are not yet considered by fluid users. Testing carried out at AMIL on different fluids with different test methods has led to a more reproducible results and a potential classification of fluids based on their gel formation potential (GFP).