S 015-111

 (5)  
Remove the cover plate from the sensor assembly box in the bulk cargo compartment.

 NOTE: The cover plate is on the left sidewall of the bulk cargo
____
 compartment at station 2010.

 E. Do the Test
 S 735-102
 (1)  Do a test of the overheat switch:
 (a)  
Make sure the AFT CARGO HT switch on the P5 overhead panel is set to ON.

 (b)  
Set the applicable CARGO HEAT switch (forward of the cargo compartment door) to the up (50 degrees F/10 degrees C) position.

 (c)  
Apply a heating source to the high temperature switch to close the control valve.

 (d)  
Make sure the applicable control valve is closed.

 (e)  
Apply a heating source to the overheat switch to increase the temperature of the switch to more than 90°F (32°C).

 (f)  
Make sure the override valve is closed.

 (g)  
Make sure the TEMP light on the AFT CARGO HT switch is off.

 (h)  
Make sure the advisory message TEMP CARGO HEAT does not show on the EICAS display.

 (i)  
Apply a cooling source to the high temperature switch to open the control valve while you maintain the overheat switch temperature above 90°F (32°C).

 (j)  
Make sure the applicable control valve opens.

 (k)  
Make sure the TEMP light on the AFT CARGO HT switch comes on.

 (l)  
Make sure the advisory message TEMP CARGO HEAT shows on the EICAS display.

 (m)  
Apply a cooling source to the overheat switch to decrease the temperature of the switch to less than 80°F (27°C).

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747-400 MAINTENANCE MANUAL
 (n)  
Make sure the override valve opens.

 (o)  
Make sure the TEMP light on the AFT CARGO HT switch goes out.

 (p)  
Make sure the advisory message TEMP CARGO HEAT does not show on the EICAS display.

 F. Put the airplane back to its usual condition:
 S 435-113
 (1)  
Remove the cooling source from the sensor assembly box.

 S 415-115

 (2)  
Install the coverplate on the sensor assembly box.

 S 865-117

 (3)  
Set the AFT CARGO HT switch on the P5 overhead panel to off.

 S 865-119

 (4)
Release the pressure in the pneumatic system (AMM 36-00-00/201).

 S 865-121

 (5)  
Remove the electrical power, if it is not necessary
 (AMM 24-22-00/201).

 S 095-123
 WARNING: REFER TO THE SPECIFIED PROCEDURE WHEN YOU REMOVE THE DOOR LOCKS
_______ FROM THE LANDING GEAR DOORS. THE DOORS CAN CLOSE QUICKLY IF THERE IS PRESSURE IN THE SYSTEM. THIS CAN CAUSE INJURIES TO PERSONS AND DAMAGE TO THE EQUIPMENT.
 (6) Remove the body and the wing gear door locks (AMM 32-00-30/201).
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747-400 MAINTENANCE MANUAL
 AFT CARGO HEAT VALVES - REMOVAL/INSTALLATION
____________________________________________
 1.  General_______
 A.  This procedure contains two tasks. The first task removes the aft cargo heat valves. The second task installs the aft cargo heat valves.
 B.  To do this procedure, you must do these steps:
 (1)  
The release of pressure from the pneumatic system

 (2)  
The removal of power to the valve

 (3)  
The installation of the landing gear ground locks and door locks

 (4)  
The removal of the valve

 (5)  
The installation of the valve

 (6)  
A functional test of the valve.
　
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