S 715-022
(12)
Make sure the EICAS caution message "BLD DUCT LEAK R" shows on the screen.
S 085-074
(13)
Remove both jumpers from the sensors.
S 715-075
(14)
Make sure the EICAS messages listed below are not shown on the screen.
(a)
BLD DUCT LEAK R
(b)
DUCT LEAK R LP A
(c)
DUCT LEAK R LP B
F. Do the Center Duct Dual Loop Sensor Test
S 485-024
(1)
Install a jumper between pins 1 and 2 of the sensor S2231.
S 715-025
(2)
Make sure the EICAS status message "DUCT LEAK C LP A" shows on the screen.
(3)
Install a jumper between pins 1 and 2 of the sensor S2230.
S 715-027
(4)
Make sure the EICAS status message "DUCT LEAK C LP B" shows on the screen.
S 485-026
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747-400 MAINTENANCE MANUAL
S 715-028
(5)
Make sure the EICAS caution message "BLD DUCT LEAK C" shows on the screen.
S 085-029
(6)
Remove both jumpers.
S 715-030
(7)
Make sure the EICAS messages listed below do not show.
(a)
BLD DUCT LEAK C
(b)
DUCT LEAK C LP A
(c)
DUCT LEAK C LP B
S 395-019
(8)
Apply the sealant, RTV-3145, PR 1913, or PR 1933, around the electrical connections on the base of the switch if it is necessary.
S 415-020
(9)
Close the access panels (AMM 26-18-02/401).
G.
Return to Normal
S 095-020
WARNING: REFER TO AMM 27-81-00/201 FOR LOCK INSTALLATION PROCEDURE.
_______ WORKING PERSONNEL SHOULD STAY AWAY FROM WING LEADING EDGE AREA. INADVERTENT OPERATION OF FLAPS MAY CAUSE INJURY TO PERSONNEL.
(1) For wing leading edge thermal switches, remove safety locks where installed.
S 415-022
WARNING: MAKE SURE THAT PERSONS AND EQUIPMENT ARE CLEAR OF THE LE AND TE
_______ FLAPS AND FLAP DRIVE MECHANISMS BEFORE YOU MOVE THE FLAP CONTROL LEVER. WITH HYDRAULIC POWER REMOVED, THE FLAPS WILL MOVE AUTOMATICALLY BY ELECTRICAL POWER WHEN YOU MOVE THE FLAP CONTROL LEVER.
(2)
For wing leading edge thermal switches, retract wing leading edge flaps (AMM 27-81-00/201).
(3)
Remove electrical power if no longer required (AMM 24-22-00/201).
S 865-023
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747-400 MAINTENANCE MANUAL
THERMAL SWITCH - REMOVAL/INSTALLATION
_____________________________________
1. General_______
A. This section contains two tasks. The first task is the removal of a thermal switch on a wings leading edge. The second task is the installation of a thermal switch on a wings leading edge.
B. There are nineteen thermal switches along the pneumatic duct in each wings leading edge. These switches are on brackets attached to ribs in the wings leading edge. There are also two thermal switches in each strut area.
C. The thermal switches find areas that are too hot in the wings leading edge and nacelle strut. The thermal switch closes and an advisory EICAS indication is shown when an overheat conditions occurs.
D. There are thirty thermal switches on the pneumatic duct in the air conditioning pack bay, and in the wheel well areas. The thermal switches find areas that are too hot caused by a leak or a break in the bleed air ducts.
E. A metal decal shows the thermal switch part number. The metal decal is installed adjacent to each thermal switch.
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