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MISCELLANEOUS SWITCHING MODULE, M7317
SEE A
A
747-400
MAINTENANCE MANUAL
EICAS
CARD FILE, M826 FIRE DETECTION
E/E EQUIPMENT COMPARTMENT CENTER
FIRE/OVHT
FIRE/OVHT
TEST
TEST SWITCH
A
Wheel Well Overheat Detection System Component Location
Figure 1 (Sheet 1)
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A
747-400
MAINTENANCE MANUAL
WING LANDING GEAR WELL
BODY LANDING GEAR WELL
SEE B
WHEEL WELL OVERHEAT CONTINUOUS LOOP SENSORS
FWD
B Wheel Well Overheat Detection System Component Location
Figure 1 (Sheet 2)
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A
747-400
MAINTENANCE MANUAL
Wheel Well Overheat Detection System Simplified Schematic
Figure 2
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A
747-400
MAINTENANCE MANUAL
(2)
When a segment of an overheat detector reaches a temperature greater than approximately 400°F, an alarm signal (low resistance) is provided by the detection circuit on the wheel well fire card. A signal is sent to EIU and then to EICAS creating a caution EICAS message.
(3)
The fire alarm signals are cancelled when the fire detector cools to approximately 360°F.
(4)
The circuit continuity can be checked by fire/overheat test module and Central Maintenance Computer.
B. Control
(1) The wheel well overheat detection system is operating when
electrical power is applied.
C. The CMC can initiate the fire detection system ground test if either of the ground tests switches is enabled and the CMC test relays are closed. The CMC initiates a ground test to determine the integrity of the fire detection card file and its inputs/outputs using the LRU's built-in test equipment. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址:747-400 AMM 飞机维护手册 防火 FIRE PROTECTION 2(11)