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 S 663-028
 CAUTION: THE REPEATED APPLICATION OF TYPE II AND TYPE IV
_______ DEICING/ANTI-ICING FLUIDS, WITHOUT THE SUBSEQUENT APPLICATION OF TYPE I DEICING/ANTI-ICING FLUID OR HOT WATER, MAY CAUSE A RESIDUE TO COLLECT IN AERODYNAMICALLY QUIET AREAS. THIS RESIDUE MAY REHYDRATE AND FREEZE UNDER CERTAIN TEMPERATURE, HIGH HUMIDITY AND/OR RAIN CONDITIONS. THIS RESIDUE MAY BLOCK OR IMPEDE CRITCIAL FLIGHT CONTROL SYSTEMS. THIS RESIDUE MAY REQUIRE REMOVAL.
 (1)  General
 (a)  
Many conditions can have an effect on which procedure you use to remove ice, snow, or frost or to make sure it does not collect and become attached to the airplane surfaces. Each operator must look at the local weather conditions. If it is possible, use the procedures that were used before with the same conditions. A general guideline is, Type II and Type IV fluids give a longer holdover time than Type I fluids. Use Type II and Type IV fluids to decrease the risk that ice, snow, or frost will collect on the airplane during a long taxi. For example, Fig. 301 gives the general guidelines to help you find the correct ice, snow, or frost removal procedure. This gives you the same procedure you will find when you use the full guidelines in this procedure.

 (b)  
Use a hot mixture of water and the Type I, Type II or Type IV deicing/anti-icing fluids when you do the one-step ice removal/anti-icing procedure. The three items below will have an effect on the quantity of water mixed with the fluid and the temperature you use. 1) The weather conditions 2) The holdover protection that is necessary 3) The condition of the airplane

 (c)  
It is necessary to have sufficient fluid temperature and flow rate to flush the ice and snow from the airplane surfaces when it collects there. More ice, snow or frost will not collect on the airplane surfaces where there is remaining fluid. The mixture and type of fluid used will have an effect on the holdover time. The weather conditions can make it necessary to apply the fluid/water mixture again. This will be necessary to remove the frozen fluid that collected since the fluid/water mixture was applied last. This is also done to increase the protection time. You can use cold water to remove snow if the conditions that follow occur. 1) There is only snow on the airplane. 2) The temperature is 34°F, or higher, and stable or on the

 increase.
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 12-33-01
 ALL  ú ú 01B Page 304 ú Feb 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL

GUIDELINE  SUMMARY OF GUIDELINES 
- ANTI-ICING FLUID - DEICING FLUID (180 TANK) TO 200`F AT THE AFTER DEICING ANTI-ICING FLUID TANK) APPLY (180-200`F AT THE - HOT WATER DEICING REMOVAL/PROTECTION SNOW, ICE OR FROST PROCEDURE - WATER THAT IS NOT HEATED  34`F OR ABOVE TEMP STABLE OR ON THE INCREASE  27`F TO 34`F TEMP STABLE OR ON THE INCREASE  BELOW 27`F 
IT IS NOT NECESSARY ABOVE FREEZING) TO USE IN TEMPERATURES OF THE FLUID IS TOO HIGH NOT RECOMMENDED (THE COST OUTSIDE. OPTIONAL TO APPLY THE ANTI-ICING FROST IN THE HANGAR OR REMOVE THE ICE, SNOW OR PERMITTED PROCEDURE TO FLUID PERMITTED PROCEDURE TO APPLY ANTI-ICING FLUID OUTSIDE. OPTIONAL TO REMOVE THE SNOW FROM THE SURFACES IN THE HANGAR OR NECESSARY DEICING IF IT IS APPLY AGAIN AFTER A MINIMUM ICE, SNOW OR FROST TO KEEP THE COLLECTION OF APPLY AS PROTECTION TO HOT WATER PROCEDURE APPLY IF YOU USE THE FROST OUTSIDE REMOVE THE ICE, SNOW OR PERMITTED PROCEDURE TO OR OUTSIDE OR FROST IN THE HANGAR TO REMOVE THE ICE, SNOW PROCEDURE RECOMMENDED NOT PERMITTED  DEICING IF IT IS NECESSARY APPLY AGAIN AFTER OCCUR AN ICE, SNOW OR FROST CONDITION WILL POSSIBLY APPLY AS PROTECTION IF FROST OUTSIDE REMOVE THE ICE, SNOW OR PROCEDURE RECOMMENDED TO NOT PERMITTED NOT PERMITTED 

Guidelines Summary: Ice, Snow or Frost Conditions
Figure 301 (Sheet 1)

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