(2)
The equipment or materials that are available.
(3)
The weather conditions at the airport where you will operate.
C. In cold weather it is necessary to drain the fuel tank sumps prior to refueling to remove water from the fuel tanks if the airplane has been idle for more than 45 minutes prior to refueling. Drain the fuel tank sumps again after refueling if the airplane has been idle for 2 hours or more after refueling, prior to departure. In cold weather water can freeze, and not let the drain valves open.
D. Definitions
(1)
Deicing is a procedure to remove the frost, ice or snow from the airplane. Hot water or a hot mixture of water and deicing/anti-icing fluid is applied to do this.
(2)
Anti-icing is a procedure to make sure that ice, snow and/or frost does not collect and become attached to the airplane surfaces. Anti-icing fluid or a mixture of anti-icing fluid and water is applied to the airplane to do this.
(3)
One step ice removal/anti-icing applies a hot deicing/anti-icing fluid or mixture of fluid and water. Use the conditions that follow to make a decision on how hot to make the fluid or the fluid and water mixture:
(a)
The ambient temperature.
(b)
The weather conditions.
(4)
Two step ice removal/anti-icing has the steps that follow:
(a)
Apply hot water or a hot mixture of deicing/anti-icing fluid and water to remove the ice.
(b)
Immediately follow with a spray of a deicing/anti-icing fluid or a mixture of deicing/anti-icing fluid and water for anti-icing. This step must be done less than 3 minutes after you started the first step. If it is necessary, do the procedure area by area.
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(5) Holdover time is the approximate time anti-icing fluid will keep the frost, ice, or snow off the airplane surfaces that have protection.
NOTE: You cannot find the level of protection or the holdover time
____ with precision. The weather conditions and the fluid/fluid mixture will have an effect on the holdover time. The person that does the procedure must use experience to make an estimate of the protection time. When there is precipitation, remove the ice from the airplane as near to the departure time as possible.
(6)
Type I (not thickened) deicing/anti-icing fluids usually have a minimum of 80 percent Glycol. The temperature makes the viscosity change but the shear stress does not. These fluids give anti-icing protection for only a short time.
(7)
Type II and Type IV (thickened) deicing/anti-icing fluids usually have a minimum of 50 percent Glycol. There is also 45 to 50 percent water plus thickeners and inhibitors. The temperature and the shear stress that is applied can make the viscosity of these fluids change. They are usually very viscous at low levels of shear stress. When the shear stress increases, their viscosity decreases very quickly. Type II and Type IV fluids give longer holdover times than Type I deicing/anti-icing fluids.
E. An airplane that is parked, for this cold weather procedure, is an airplane in the loading area for a short time to be prepared for the departure. If the airplane stays in the loading area through the night in cold weather conditions, refer to the Guidelines for Parked Airpalnes in this procedure. Cold weather operation does not include an airplane that is parked for a long time. This is included in Chapter 10.
F. Slush is ice and/or snow that is not fully melted. Thus, the ice removal/anti-icing procedures for ice and snow removal apply to slush. A special procedure for slush is not necessary.
G. Start electronic equipment in the cold weather conditions the same as in the usual conditions. A special procedure is not necessary.
H. The engine start procedure for cold weather operation is given in Chapter 71.
I. The APU start procedure is given in Chapter 49.
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