B. The detection system consists of the following:
(1) Engine Fire and Overheat Detection (26-11-00)
(a) Four identical engine fire detection loops are employed, each with continuous dual-element sensors. Sensor elements are located at the critical locations in the engine nacelle and engine, and are connected in a continuous loop such that a fire or overheat in any area will cause an alarm. Each sensor has two separate loops, identified as A and B, either of which may provide the fire detection circuit. An automatic fault circuit notifies the flight crew of a failure of a loop, so that the other loop may be selected. The flight crew may test the system by test switch on P5 pilot's overhead panel. The flight crew also will be notified of fire and fault condition by master fire warning light, fire bell, warning, caution, advisory, and status EICAS messages.
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MAINTENANCE MANUAL
ZONE F SMOKE DETECTION
COMBIS FREIGHTERS PASSENGER AIRPLANES
AIRPLANES WITH ZONE B SMOKE DETECTION AIRPLANES WITH ZONE F SMOKE DETECTION
Detection Systems
Figure 1
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C85074
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MAINTENANCE MANUAL
ENGINE, APU, LOWER CARGO AND MAIN DECK CARGO
FIRE CONTROL MODULE - P5 PILOTS' OVERHEAD PANEL WARNING/CAUTION LIGHT - P72 MAIN INSTRUMENT LIGHTSHIELD PANEL FIRE/OVERHEAT TEST SWITCH - P5 PILOTS' OVERHEAD PANEL SELF-TEST SWITCH - INSTALLED ON MODULE CENTRAL MAINTENANCE COMPUTER (CMC) - P8 PILOTS' CONTROL PANEL P9 FORWARD ELECTRICAL CONTROL PANEL COMBIs ONLY FREIGHTERS
Fire, Smoke, or Overheat Detection Indications
Figure 2
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(2)
AIRPLANES WITH NACELLE OVERHEAT DETECTION; Engine Nacelle Overheat Detection (26-11-50)
(a) There is a temperature sensor for each engine. The nacelle temperature sensor is a transducer. The resistance of the temperature sensor increases as the temperature increases. The increase in the resistance will result in an increase in the voltage in the temperature sensor. Each temperature sensor is connected to the YLPA026 ATAC card. The multiplexer within the ATAC card continuously monitors the voltage input from the operational amplifier. If there is a difference of 50 degrees celsius or more between any two engines, an EICAS message will appear. The system is tested by the FIRE/OVHT TEST switch.
(3)
Lavatory Smoke Detection System (26-13-00)
(a) Each lavatory is monitored for presence of smoke or equivalent contaminants by a smoke detector unit. A smoke detector unit provides an aural warning to alert cabin attendants in event of a lavatory fire. The smoke detection system requires power from the airplane 28-volts dc bus 2 and 4.
(4)
Main Deck Cargo Compartment Smoke Detection System (Combi and Freighters only) (26-14-00)
(a) The smoke detection system monitors main deck cargo compartment. There are a total of six zones (sixteen on Freighters) . Each zone has two smoke detectors for a total of twelve (thirty-two on Freighters) smoke detectors on main deck cargo. The photocell in each smoke detector monitors the sample air for smoke. When the sample air containing smoke enters the smoke detector, light from a constant source is reflected onto the photocell causing an increase in output voltage and a signal is relayed to the flight deck. The generated signal will create master fire warning light, fire bell, warning, and advisory EICAS messages.
(5)
Overhead Crew Rest Area Smoke Detection (When Installed) (26-14-20)
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本文链接地址：747-400 AMM 飞机维护手册 防火 FIRE PROTECTION 1(5)
