D.  Disconnect repellent supply line from valve coupling.
WARNING:  DO NOT LET THE RAIN REPELLENT FLUID TOUCH YOUR SKIN OR EYES. THE FLUID CAN CAUSE IRRITATION. DO NOT BREATHE THE FUMES. IF THE FLUID TOUCHES YOU, WASH YOUR SKIN OR EYES WITH WATER.
CAUTION:  DO NOT DISTURB OR ATTEMPT TO REMOVE SOLENOID VALVE IF SYSTEM IS PRESSURIZED AS FLUID MAY BE SPRAYED OVER ADJACENT STRUCTURE OR PERSONNEL.
E.  Remove valve and remove coupling and O-ring from valve.
2.  Install Solenoid Valve (Fig. 401)
A.  Install O-ring and coupling on lower end of valve (inlet port).
B.  Position valve above repellent supply line with solenoid on forward side and flow direction arrow pointing up.
NOTE: The rain repellent solenoid must not touch the wiper motor.
C.  Connect repellent supply line to coupling and time delay module to solenoid receptacle.
D.  Close circuit breakers opened in step 1.B.
E.  Install respective spray nozzle and test system (Ref 30-43-11 R/I).
525 
30-43-21 Page 402  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Feb 20/93 

WATER AND TOILET DRAIN ANTI-ICING SYSTEM -
DESCRIPTION AND OPERATION
1.  General
A.  The fore and aft toilet drains are electrically heated to stop ice from forming in the drain connection and preventing removal of the drain cap or obstructing the toilet drain (Fig. 1). The heating element is an integral part of the drain connector fitting gasket, and operates on 115-volt ac current. The heaters are controlled by circuit breaker(s) on the P18 load control center (Fig. 2).

591  Water and Toilet Drain Anti-Icing System Equipment Location 
Jan 20/82  Figure 1  30-71-0 
Page 1 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

B.  Drain Mast Heaters
(1)  
The water drain mast is electrically heated to prevent ice from forming and blocking the drain (Fig. 2). The heating element operates on either 28 volts ac for low heat ground operation or 115 volts ac for high heat air operation. Low heat power is supplied from the 28-volt ac main bus No. 2 through the DRAIN MAST GND circuit breaker.  On GJ ALL EXCEPT B-2524, high heat power is supplied from the 115-volt ac main bus No. 2 through the DRAIN MAST AIR circuit breaker. On GJ B-2524, high heat power is supplied from the 115-volt ac main bus No. 1 through the DRAIN MAST AIR circuit breaker. Both circuit breakers are located on the P18 load control center.

(2)  
For low heat ground operation of the drain mast, 28-volt ac power is provided by two relays, a landing gear air sensing relay in the landing gear module and an external power sensing relay on the bus protection panel (Ref Chapter 32, Landing Gear Air-Ground Sensing and Chapter 24, External Power). When the airplane is in the air, 115-volt ac power is used for heating the drain mast; but, upon landing, the landing gear air safety sensing relay is de-energized, thereby switching to the 28-volt ac power supply for low heat ground operation to prevent the heater from overheating and possibly burning out the heating element. Additional protection against overheating of the drain mast is provided by the external power sensing relay which prevents inadvertent application of 115 volts ac to the heater during maintenance in the event the airplane is raised on jacks. The external power sensing relay is energized when external power is supplied to the airplane.

5C8 
30-71-0 Page 2  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Jun 20/89 

5C8  Water and Toilet Drain Anti-Icing System Circuit 
Jun 20/89  Figure 2 (Sheet 1)  30-71-0 
Page 3 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

F89075
Water and Toilet Drain Anti-Icing System Circuit  5C8 
30-71-0  Figure 1  Jun 20/89 
Page 4 
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details. 

WATER AND TOILET DRAIN ANTI-ICING SYSTEM - TROUBLE SHOOTING
1.  General
A.  Before using the following trouble shooting chart, test the system per adjustment/test.
B.  Trouble shooting procedures are based on the assumption that electrical power is available. If remedy in procedure does not correct problem, check wiring continuity using wiring diagram.
C.  Heating system operates on 28 volts ac on ground and 115 volts ac in the air.
D.  There are no indicator lights or gages to verify that the heater system is functioning. Indication of a malfunction will appear as a clogged drain line caused by water freezing in the mast.
　
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