(2)  
Install the lockwire (Ref 20-11-28/401).

 S 434-009

 (3)  
Install the electrical connector DS2071 on the switch.

 S 864-010

 (4)  
Remove the DO-NOT-CLOSE tag and close the following circuit breaker for the aft cargo underfloor heat control switch:

 (a)  On the P7 Overhead Circuit Breaker Panel. 1) 7H9 CARGO HEAT AFT

 (5)  
Apply electrical power (Ref 24-22-00/201).

 (6)  
Pressurize the pneumatic system (Ref 36-00-00/201).

 (7)
Set the AFT CARGO HT switch on the P5 overhead panel to ON.

 S 864-011
 S 864-012
 S 864-013
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747-400 MAINTENANCE MANUAL
 S 864-014
 (8)  To enable the underfloor heat control switch, set the CARGO COND AIR FLOW RATE switch to the LOW position.
 NOTE: The CARGO COND AIR FLOW RATE switch is on the P461 overhead
____
 maintenance panel.

 S 724-015
 (9)  Do a test of the switch:
 (a)  
Apply the cooling source to underfloor heat control switch to decrease the temperature of the switch to less than 32°F (0°C).

 (b)  
If the temperature in the compartment is more than 80°F (27°C), apply the cooling source to the aft cargo overheat switch also.

 NOTE: The aft cargo overheat switch is in the bulk cargo
____ sensor assembly box, on the left side of the box. The bulk cargo sensor assembly box is on the bulk cargo left sidewall at station 2010.
 (c)  
Make sure air comes from the heat ducts that are below the compartment floor.

 (d)  
Apply the heating source to the underfloor heat control switch to increase the temperature of the switch to more than 42°F (6°C).

 (e)  
Make sure the airflow from the heat ducts stops.

 (f)  
If applicable, remove the cooling source from bulk cargo sensor assembly box.

 (g)  
If removed, install the coverplate on the bulk cargo sensor assembly box.

 S 864-016
 (10)
 Set the AFT CARGO HT switch on the P5 overhead panel to off.

 (11)
 Set the CARGO COND AIR FLOW RATE switch to OFF.

 (12)
 Release the pressure in the pneumatic system (Ref 36-00-00/201).

 (13)
 Remove electrical power (Ref 24-22-00/201).

 S 864-017
 S 864-018
 S 864-019
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747-400 MAINTENANCE MANUAL
 AFT CARGO HEAT DUCT - REPAIR
____________________________
 1.  General_______
 A.  This task gives instructions to repair the heat duct in the aft cargo compartment.
 B.  This task has two procedures for the repair of the heat duct while it is on the airplane:
 (1)  
The first procedure tells to repair a short section of the heat duct. A short segment of duct is 12 inches (305 mm) or less.

 (2)  
The second procedure tells to repair a long section of the heat duct. A long segment of duct is more than 12 inches (305 mm).

 C.  The heat duct is made from aluminum or a BMI composite material. When you repair a short section or a long section of an aluminum heat duct, you must use aluminum to make the repairs. When you repair a short section of a composite heat duct, you must use a titanium sleeve to make the repairs. When you repair a long section of a composite heat duct, you must use a BMI composite material and two titanium sleeves to make the repairs.
 TASK 21-44-09-308-001
 2.  Aft Cargo Heat Duct Repairs (Fig. 801)___________________________
 A.  Special Tools and Equipment
 (1)  
Scrivets - P/N 231-700055-00-3704,
 Fastex Co.
 195 East Algona Road
　
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本文鏈接地址：747-400 AMM 飛機維護手冊 空調 AIR CONDITIONING 1(167)