(9)
Miscellaneous
(a)
Pitot Probe, Static Ports, and Total Air Temperature (TAT) Probes (Fig. 203). 1) Check and remove any ice adhering to the surface within four feet of pitot probe, static port, and TAT probe inlets. 2) Do not spray deicing/anti-icing fluid directly at or into pitot inlets, static ports or TAT probes. 3) If static openings become clogged with ice, gently apply warm air until the ice melts.
4) If excessive fluid was applied to fuselage in vicinity of static ports, check the nearest in-line drain to clear water which may have accumulated.
(b)
Drains
1) Check that all waste water and condensate drains on the airplane are free of ice or obstructions. Plugging of drains is not necessary during deicing or anti-icing operation, however, fluid spray must not be directed at these drain areas.
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(c) Airstairs
1) Retract stairs as soon as possible to prevent excessive ice or snow accumulations. Snow accumulations may be removed by sweeping or brushing. Should ice accumulation occur on the stairs, remove the ice with deicing fluid. Be careful not to spray deicing fluid into door opening.
2) Ice and snow accumulation may prevent extension of the stairs from outside the airplane. Deice the external controls and apply anti-icing fluid.
(d)
Angle of Airflow Sensor (Fig. 203).
1) Check that sensors are free of ice and/or snow and sensors move freely. Apply deicing fluid as required.
(e)
Windshield Wiper Blades 1) Remove accumulated ice from windshield wiper blades.
4. Hot Water Deicing
A. Hot water at 180-200°F maximum tank temperature can be used effectively to remove ice and snow from airplane surfaces when the ambient temperature is 28°F, stable or rising.
B. To prevent water from refreezing, anti-icing fluid should be applied to the surface immediately following hot water deicing.
C. Freezing of residual water in devices used for hot water deicing may be minimized by adding 10% glycol to the hot water tank.
5. One Step Deicing/Anti-Icing
A. One step deicing/anti-icing, using deicing/anti-icing fluid heated to 180-200°F, is effective for ice and snow removal from airplanes when the temperature is below 28°F. After the mixture has been used to clear the aircraft surfaces, the residual fluid will provide some anti-ice protection. If the removed material deicing/anti-icing fluid refreezes before running off the airplane, it indicates that an incorrect anti-icing fluid dilution was used. Application of additional deicing/anti-icing fluid will be required to obtain greater protection.
B. The fluid mixed with the water can be either Type I deicing/anti-icing fluid, Type II or Type IV deicing/anti-icing fluid. The holdover time will be longer with the Type II and Type IV deicing/anti-icing fluid. In either case, the percentage of fluid in the mixture should be based on airline experience, fluid specifications, or manufacturer's recommendations and weather conditions.
C. If an additional treatment is needed before the next flight, perform a complete deicing/anti-icing.
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6. Two-Step Deicing/Anti-icing
A. Two-step deicing/anti-icing as defined in paragraph 1.D.(4) is normally the preferred method for continuing precipitation conditions. The second step must be performed within 3 minutes at the beginning of the first step, if necessary, area by area.
B. The holdover time realized from anti-icing is dependent on the fluid used and weather conditions. Therefore, frequent inspections must be made to determine when additional applications are needed.
C. If an additional treatment is needed before the next flight, perform a complete deicing/anti-icing.
7. Operation Checks
A. Prior to engine start, checks must be made to ensure the systems will function properly.
(1)
Operate all control surfaces. An observer on the ground should verify movement to full travel. If there is reason to suspect frozen seals or obstructions (ice, snow) in the balance panel bays, move the control surfaces manually prior to moving with power.
(2)
Check pitot probe, engine inlet or strut mounted probe and static port openings for obstructions of ice or snow.
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