DRAIN AND WATER SUPPLY LINE HEATING -WATER TANK DRAIN HEATER

EFFECTIVITY BEJ ALL  30-71-00 
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D633W101-BEJ  Jan 05/2002 

DRAIN AND WATER SUPPLY LINE HEATING -GRAY WATER DRAIN LINE HEATER AND THERMOSTAT

General
The forward drain mast has a heated hose identified as the gray water drain line hose heater.
The heated hose has a remote thermostat identified as the gray water drain line hose heater thermostat.
Each component, the hose and the thermostat, is an LRU. The wires do not have electrical connectors. To replace a component you must splice the wires together.
The aft drain mast does not have a heated hose.
Location
The heated hose and its thermostat are in the forward left wing-to-body fairing.
An access panel aft of the drain mast supplies access to the thermostat.
Functional Description
Power for the drain mast heaters comes through an air/ground relay. The heaters get 28v ac on the ground and 115V ac in the air.
The thermostat opens the circuit when the temperature is more than 50F (10C). The circuit closes when the temperature is less than 45F (7C).
Training Information Point
You can remove the drain mast to get better access to the heated hose.
EFFECTIVITY BEJ ALL  30-71-00 
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D633W101-BEJ  Sep 05/2002 

DRAIN AND WATER SUPPLY LINE HEATING -GRAY WATER DRAIN LINE HEATER AND THERMOSTAT

EFFECTIVITY BEJ ALL  30-71-00 
Page 11 
D633W101-BEJ  Jan 05/2002 

DRAIN AND WATER SUPPLY LINE HEATING -DRAIN MAST HEATER

General
There are drain mast heaters in the forward and aft drain masts to prevent freezing. Each drain mast is an LRU and is interchangeable with the other.
The heater wires on the drain masts do not have electrical connectors. You must splice the wires when you replace a drain mast.
Location
Both drain masts are on the left wing-to-body fairing.
You can remove the drain mast from the fairing. It is not necessary to open a panel to get access to the drain mast.
Functional Description
Power for the drain mast heaters comes through an air/ground relay. The heaters get 28v ac on the ground and 115v ac in the air.
An overheat thermostat will opens the circuit when the temperature is greater than 250F (121C). The circuit closes when the temperature is less than 250F (121C).
EFFECTIVITY BEJ ALL  30-71-00 
Page 12 
D633W101-BEJ  Sep 05/2002 

DRAIN AND WATER SUPPLY LINE HEATING -DRAIN MAST HEATER

EFFECTIVITY BEJ ALL  30-71-00 
Page 13 
D633W101-BEJ  May 05/2002 

DRAIN AND WATER SUPPLY LINE HEATING -WATER DRAIN LINE HEATERS -INTRODUCTION

Purpose
Water drain line heaters keep the gray water drain lines in the lower part of the fuselage from freezing.
General Description
The heater is a flexible element installed around the drain line. The heater also includes an overheat switch (not shown). Electrical connectors attach to the heater and to ground studs. Metal clamps attach the ground studs to the drain line. (Some assemblies have only one connector and ground stud.)
Thermal insulation (held in place with tape) covers the drain line and heating element. Adhesive markers identify the flow direction and part number. On some drain lines, a clamp holds a thermostat.
Location
The heated gray water drain lines are below the floor panels and walkways of the forward, aft, and bulk cargo compartments.
Training Information Point
The heater is an LRU. In some places it is easier to replace the heater if you remove the drain line from the airplane. If you do this, you must do a leak check when you install the drain line.
When you replace a heater, you need to do an operational test. Cool the thermostat with crushed ice or freeze spray and use a clamp-on ammeter to measure current through the heater.
CAUTION:  MAKE SURE YOU PUT THE CORRECT HEATER ASSEMBLY ON THE TUBE ASSEMBLY. IF THE
HEATER  ASSEMBLY  IS  INCORRECT,  IT  WILL 
CAUSE  THE  DRAIN  LINES  TO  FREEZE  OR 
BECOME TOO HOT. 

EFFECTIVITY BEJ ALL  30-71-00 
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D633W101-BEJ  Sep 05/2002 

DRAIN AND WATER SUPPLY LINE HEATING -WATER DRAIN LINE HEATERS -INTRODUCTION

EFFECTIVITY BEJ ALL  30-71-00 
Page 15 
D633W101-BEJ  Jan 05/2002 

DRAIN AND WATER SUPPLY LINE HEATING -WATER DRAIN LINE HEATERS -FUNCTIONAL DESCRIPTION
　
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