757 AMM 飞机维护手册 SERVICING 1(15)

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 C.  Do not drain the sumps while you fill the airplane with fuel or immediately after you fill the airplanes with fuel. The water will be mixed with the fuel. In cold weather the water can freeze. This could cause the drain valve to stay in the closed position or cause damage to the o-ring when you open the valve. It could also prevent proper re-seating of the primary or secondary poppet after you sump. For cold weather maintenance, refer to AMM 12-33-01/301.
 D.  Look at each fuel sample for water, for ice, or for contamination. Water in the fuel usually shows as a layer below the fuel or as small bubbles in the fuel. The ice crystals usually shows as a cloudiness or a haziness in the fuel. Fuel with no water, ice, or contamination is clear and bright. You can easily see material through it.
 NOTE:____Jet-A fuel can have different colors. It can have a range of colors from yellow (straw) color to no color. The words "clear and bright" do not refer to the color of fuel. Yellow fuel or fuel that has no color can be "clear and bright" as specified above.
 NOTE: Put one or two drops of food coloring into the container
____ before you drain a fuel sample into it. This will help you find water in the fuel, since the water will have color.
 E.  A large quantity of water drained from one tank before fueling can show a blocked automatic sumping pump. For removal of an automatic sumping pump, refer to AMM 28-22-06/401.
 TASK 12-11-03-683-001
Drain the Fuel Tank Sumps (Fig. 301)

_________________________

 A.  General
 (1)  Jet fuels can have unwanted water that it collects during airplane operation. This is because the air can be moist or wet and condensation can get into the fuel tanks. It is necessary to drain the fuel tanks sumps regularly to remove this unwanted water. Thebest airplane attitude to drain the sumps is a pitch of 0.3 degreenose-down (+/- 0.1 degree) longtitudinal, and a 0.0 degrees (+/- 0.1degree) lateral roll.
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757 MAINTENANCE MANUAL
FLAPPER
FLANGE
TANK 
SUMP 
SUMP DRAIN  FITTING 
VALVES 
0-RING 
SEE  A 
SUMP DRAIN 
VALVES 
VALVE 
SEE  B  POPPET  BODY  LOWER SURFACE 
SUMP DRAIN  VALVE  OF FUEL TANK 
VALVES  MAIN OR SURGE FUEL TANK SUMP DRAIN VALVE 
SEE  A 
A 
FLAPPER 

VALVE 
FLAPPER  BODY  LOWER SURFACE 
OF FUEL TANK 
POPPET  O-RING 
FLANGE  VALVE 
TANK 
SUMP 
FITTING  DRAIN 
LINE 

0-RING
VALVE LOWER BODY SURFACE OF FUEL TANK
DRAIN LINE FITTING
DRAIN LINE SEE C FITTING
CENTER FUEL TANK SUMP DRAIN VALVE
B
DRAIN LINE FITTING
C
Fuel Sump Draining Figure 301
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 ALL  ú ú 01 Page 302 ú Dec 20/89
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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757
MAINTENANCE MANUAL

SUMP DRAIN VALVE FLAPPER ADAPTER
CENTER TANK

SUMP DRAIN VALVE
FLAPPER
SUMP DRAIN VALVE ADAPTER SUMP DRAIN
DRAIN HOSE
FUEL SAMPLING EQUIPMENT

SHUTOFF VALVE

SUMP DRAIN ADAPTER AND HOSE
Fuel Sump Draining Figure 302
B58152
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 ALL  ú ú 02 Page 303 ú Mar 20/93
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
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757
MAINTENANCE MANUAL

 B.  Equipment
 (1)  
Fuel Sampling Receptacle, B12004-1

 (2)  
Clear plastic or glass container - 1 gallon capacity
　
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