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2. Equipment and Materials
A. Ground equipment compatible with and suitable for application of Type I, II or IV deicing/anti-icing fluids and water.
WARNING: BE SURE TO USE EQUIPMENT DESIGNATED FOR THE FLUIDS BEING APPLIED. MECHANICAL OR EQUIPMENT SHEARING OF MANY TYPE II AND IV DEICING/ANTI-ICING FLUIDS REDUCES THEIR VISCOSITY AND, THEREFORE, THE ESTIMATED HOLDOVER TIME. BE SURE TO REFER TO MANUFACTURER'S GUIDELINES FOR THE SPECIFIC FLUID BEING USED.
(1)
Deicing/Anti-icing Truck
(2)
Boomtruck or Cherry-picker
(3)
Water
(4)
Hot Air Source
(5)
Type I, II or IV Deicing Fluid
(6)
Type I, II or IV Anti-Icing Fluid
B. Materials
NOTE: The applicable fluids which obey the Boeing document D6-17487, "Certification Test of Airplane Maintenance Material" and conform to any of the following specifications, are acceptable fluids.
(1) Type I (newtonian) fluids (Ref Chapter 20):
(a)
G02301 fluid SAE AMS 1424 latest revision
(b)
G00072 MIL-A-8243D Types 1 and 2
NOTE: MIL-A-8243D Type I fluid is acceptable in a 50/50 fluid/water concentration. MIL-A-8243D Type II / IV fluid is acceptable in any concentration. There are no holdover time guidelines for MIL-A-8243D fluids.
(2) Type II and IV (non-newtonian) fluids (Ref Chapter 20):
(a) G02301 fluid SAE AMS 1428 latest revision
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3. Guidelines
A. General
(1)
There are many conditions influencing a decision concerning the method of ice, snow, or frost removal and the method of protection from ice, snow, and frost accumulation. The best methods must be determined by the individual operator based on his experience and the prevailing local conditions. However, as a general guideline, Type II and Type IV fluids provide a longer holdover time than Type I fluids. Use of Type II and Type IV fluids reduces the risk of ice, snow, or frost accumulation on the aircraft during a long taxi. For example, Figure 201 provides a summary of the guidelines to aid in determining an procedure.
(2)
One-step deicing/anti-icing is performed using a heated mixture of water and either Type I, Type II or Type IV deicing/anti-icing fluids. The fluid dilution and temperature used depends on the weather, the desired hold over protection and condition of the airplane. Ice and snow removal requires sufficient fluid temperature and flow rate to flush the accumulation from aircraft surfaces. The residual fluid on the aircraft surfaces provides protection against further accumulation of ice, snow, or frost, with the holdover time dependent on the mixture and type of fluid used. Depending on weather conditions, repeated application of the fluid/water mixture may subsequently be required in order to remove any additional frozen deposits that may have accumulated, and to extend the period of protection. If only snow is present on the airplane and the temperature is 34°F or higher, and stable or rising, unheated water can be used to remove snow.
(3)
Deicing fluid and hot water should be heated to 180-200°F, at the tank, for best results in ice or snow removal. A fine to medium spray is recommended for best dispersion of the fluid across a large area of ice or snow for maximum melting effect. A solid stream is recommended for flushing ice or snow from airplane surfaces. However, the maximum force on the surfaces, to prevent damage, must not exceed 10 psi on an area of 25 square inches.
CAUTION: DO NOT DIRECT SOLID FLUID STREAM NORMAL TO SURFACE. APPLY AT LOW ANGLE TO PREVENT DAMAGE TO AIRPLANE SURFACES. DO NOT USE HIGH PRESSURE SPRAY TO "BATTER" ICE AND SNOW OFF AIRPLANE SURFACES.
(4)
To determine the percentage of deicing/anti-icing fluid that should be used in the deicing mixture at a given temperature, refer to airline procedure or the manufacturer's specifications for the particular fluid. Tables 1 and 2 in this section can be used for Type I fluids conforming to MIL-A-8243 and for Type II and IV fluids conforming to the AEA Specifications. If the melted ice or snow, mixed with deicing/anti-icing fluid refreezes on the airplane as it runs off, it indicates a greater concentration of deicing/anti-icing fluid is required.
(5)
A coating of anti-icing fluid or a mixture of anti-icing fluid and water, depending on the atmospheric temperature, will offer protection from ice, snow, and frost if the fluid is applied to a dry wing before such conditions begin. Consideration should also be given to anti-icing a cold soaked airplane in precipitation conditions where the air temperature is above freezing. Since the airplane external surfaces may be below the freezing point, ice may form and adhere to the surface. Clear ice may be present below the layer of snow or slush, which is difficult to detect. Check to ensure removal of all ice after deicing or deicing/anti-icing. Some cases may require inspection by touch.
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