Chapter 3 - Deicing/Anti-icing Fluids

Aerodynamics

39.  Deicing and/or anti-icing fluid remaining on the aircraft following the deicing and/or anti-icing operation have an affect on the aerodynamic performance of any aircraft. As the temperature decreases, fluids generally become more viscous and have an increased negative effect on the aerodynamics. As an aircraft gains speed on its take off run the aerodynamic shear forces cause the fluids to flow off the aircraft's surfaces. The amount of fluid that is sheared off the aircraft depends upon the speeds reached during the take off run and the time it took to reach those speeds.

40.  There are two separate aerodynamic acceptance tests, one for faster aircraft and one for slower aircraft. The objective of the tests is to determine the coldest temperature at which the deicing/anti-icing fluids have acceptable aerodynamic characteristics as they flow off lifting and control surfaces during the take off ground acceleration and climb. The aircraft manufacturer should be consulted to establish which fluids could be safely used on their models of aircraft.