Chapter 4 - Preventative Measures and Deicing Procedures

Wing Covers

5.  Many operators of smaller aircraft have found wing covers to be an effective way to prevent the build up of contamination on wings. Wing covers, although effective, have some drawbacks. Extreme care is required in both installation and removal of the covers in order to avoid damage to the aircraft. Depending on the aircraft type, ladders or a similar device are required during installation and removal of covers; and in inclement weather safety is a concern when climbing ladders due to the possibility of slipping. Installing covers on wings that are already contaminated often leads to problems. One other drawback of wing covers is the requirement for a large area to store the covers and allow them to dry (i.e. a place to hang them). There have also been problems of wings "sweating" while covered, and then having the covers freeze to the wings.

6.  In some circumstances, when the Aircraft Manufacturer recommends it, dry, powdery snow can be removed by blowing cold air or compressed nitrogen gas across the aircraft surface. In other circumstances, a shop broom could be employed to clean certain areas accessible from the ground. Heavy, wet snow or ice can be removed by placing the aircraft in a heated hangar, by using solutions of heated FPD fluids and water, by mechanical means such as brooms or squeegees, or a combination of all three methods. Should the aircraft be placed in a heated hangar ensure it is completely dry when moved outside, otherwise, pooled water may refreeze in critical areas or on critical surfaces.

7.  Conditions may be encountered whereby cold dry snow is falling onto the cold wing of an aircraft. The wind often causes the snow to swirl and move across the surface of the wing and it is evident that the snow is not adhering to the wing surface. Under these circumstances the application of de/anti-icing fluid to the wing of the aircraft would result in the snow sticking to the fluid. Under such operational conditions it may not be prudent to apply fluids to the wing.

However, if snow has accumulated at any location on the wing surface it must be removed prior to take-off. It cannot be assumed that an accumulation of snow on a wing will "blow off" during the take-off.

8.  A frost that forms overnight must be removed from the critical surfaces before take-off. Frost can be removed by placing the aircraft in a heated hangar or by other deicing procedures. A recent accident in Birmingham England is a prime example of such an occurrence.