Operating aircraft during cold weather months is challenging and removal of ice, frost, or snow is essential for safe flight. In addition, airport use of runway de-icers and applications of de-icing/anti-icing fluids during winter weather events can add to corrosion concerns.
We are aware that some local airports use potassium acetate or potassium formate- based runway de-icing products. While these types of de-icers are advertised to be environmentally friendly, they are known to have chemical properties similar to urea or salt. Salt is destructive due to its ability to serve as an electrolyte, which can chemically attack a number of common aircraft alloys.
Research indicates the interaction between aircraft de-icing/anti-icing fluids may contribute to forming residual gels. During some weather conditions, the residue from snow and ice removal fluids can collect moisture and congeal into a gel-like substance that can collect in landing wheel wells, and aerodynamically quiet areas of the wing around the ailerons and wing flaps.
Airplane de-icing/anti-icing fluids are often combined with runway de-icers when airplane fluids flow off the wings during takeoff roll onto treated runways. Wet taxiways and the use of thrust reversers can also mix the two fluids together forming residue on airplane surfaces.
For this reason it is important to pay particular attention to the frequency of applications of de-icing/anti-icing fluids and watch for unwanted gel formations in wheel wells, rear wing spars, and flight control hinge areas. If a residue is discovered, the airplane should be washed as soon as possible.
Operators can refer to the Exterior Cleaning procedures in Chapter 12 of the applicable maintenance manual. Information on the Description and Operation of Corrosion can also be found in Chapter 51.