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ALL ú ú 02B Page 311 ú Jun 10/97
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
S 663-027
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 CRITICAL FLIGHT CONTROL SYSTEMS. THIS RESIDUE MAY REQUIRE REMOVAL.
(2) Specific Requirements
(a) Control Surfaces
1) Retract the wing flaps, slats, and spoilers during icing conditions or when the snow falls. If it is necessary to operate these controls, make sure they are not blocked by ice or snow before you retract them.
NOTE: If an airplane comes to the gate with the flaps not
____ fully retracted during icing conditions or when the snow falls, examine those flaps that are not fully retracted. Look for ice or snow that has collected before they are retracted.
2) All of the control surfaces must have no ice, snow, or frost on them. After you remove the ice, make sure there is no moisture collected in the hinges, guide tracks and actuators for the flight controls. This moisture could subsequently freeze. Apply deicing/anti-icing fluid for protection.
3) Open the leading edge devices and look for ice or snow.
(b) Wing and Horizontal Tail Surfaces
1) The wing and horizontal tail surfaces must have no ice, snow, and frost on them.
NOTE: A layer of frost 1/8 inch thick or less on the lower
____ wing surfaces (in the spar area) is permitted if it is caused by very cold fuel. But, all of these areas must have no ice, snow or frost on them:
-Leading edge devices.
-Control surfaces.
-Tab surfaces.
-The top wing surface.
2) The leading edge surfaces must have no ice, snow or frost on them. Examine the areas between the surfaces that move and the surfaces that do not move to make sure there is no ice.
3) The right and left sides of the horizontal stabilizer must get the same and full ice removal/anti-icing procedure.
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ALL ú ú 01B Page 312 ú Oct 18/00
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
(c)
(d)
A
747-400 MAINTENANCE MANUAL
Fuselage and Vertical Tail Surfaces
CAUTION:_______ BE CAREFUL WHEN YOU REMOVE ICE AND SNOW FROM THE
FUSELAGE AREA WHERE THERE ARE LIGHTS AND ANTENNA. IF
YOU ARE NOT CAREFUL, YOU CAN CAUSE DAMAGE TO THE
EQUIPMENT.
1) The fuselage and the vertical tail surfaces must have no ice or snow on them. This will decrease the aerodynamic drag and the weight of the airplane.
NOTE: Thin hoar frost is permitted on the top surface of
____ the fuselage if all the vents and ports are clear. Thin hoar frost is a white layer of constant thickness with a sharp crystalline texture. It usually occurs on surfaces that are out on a cold night with no clouds. Hoar frost is thin. You can see items on the surface below the layer of frost such as paint lines, marks or letters.
2) Remove all of the snow from the nose radome area. If you do not do this, the snow will blow aft and decrease the pilot's vision on the takeoff.
3) Do not apply hot deicing fluid or hot water directly on the pilot's windshield or the passenger windows. You can let the fluid flow on the windows after you apply it to the top of the cabin. This is permitted since the fluid will be cool when it gets to the windows.
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