.
APU fire extinguishing powered by the hot battery bus.
APU Fire Detection
A single fire detection loop is installed on the APU. As the temperature of the detector increases to a predetermined limit, the detector senses a fire condition. The APU fire warning switch remains illuminated until the temperature of the detector has decreased below the onset temperature.
The system contains a fault monitoring circuit. If the loop fails, the APU DET INOP light illuminates indicating the APU fire detection system is inoperative.
The indications of an APU fire are:
.
the fire warning bell sounds
.
both master FIRE WARN lights illuminate
.
the APU fire warning switch illuminates
.
the APU automatically shuts down
.
the wheel well APU fire warning horn sounds, (on the ground only), and
the wheel well APU fire warning light flashes.
APU Fire Extinguishing
The APU fire extinguisher system consists of one APU fire extinguisher bottle, an APU fire warning switch, an APU BOTTLE DISCHARGE light, and an EXT TEST switch. The APU ground control panel located in the right main wheel well also contains an APU fire warning light, an APU BOTTLE DISCHARGE switch, an APU fire control handle and APU HORN CUTOUT switch.
The APU fire warning switch is normally locked down to prevent inadvertent shutdown of the APU. Illumination of the APU fire warning switch unlocks the switch. The switch may also be unlocked manually.
Pulling the APU Fire Warning switch up:
.
provides backup for the automatic shutdown feature
.
deactivates the fuel solenoid and closes the APU fuel shutoff valve
.
closes the APU bleed air valve
.
closes the APU air inlet door
.
trips the APU generator control relay and breaker
.
allows the APU fire warning switch to be rotated for discharge
.
arms the APU fire extinguisher bottle squib.
Copyright . The Boeing Company. See title page for details.
8.20.4 April 28, 2000
Fire Protection -System Description 737 Flight Crew Operations Manual
Rotating the APU fire warning switch in either direction electrically “fires” the squib discharging the extinguishing agent into the APU. The APU BOTTLE DISCHARGE light illuminates after a few seconds, indicating the bottle has discharged.
Main Wheel Well Fire Protection
Main wheel well fire protection consists of fire detection powered by the No. 1 AC transfer bus.
Note: The main wheel well has no fire extinguishing system. The nose wheel well does not have a fire detection system.
Main Wheel Well Fire Detection
A single fire detector loop is installed in the main wheel well. As the temperature of the detector increases to a predetermined limit, the detector senses a fire condition. The WHEEL WELL fire warning light remains illuminated until the temperature of the detector has decreased below the onset temperature.
The indications for a main wheel well fire are:
.
the fire warning bell sounds
.
both master FIRE WARN lights illuminate
.
the WHEEL WELL fire warning light illuminates.
Cargo Compartment Fire Protection
Cargo fire protection consists of these systems:
.
cargo compartment smoke detection powered by DC bus 1 and DC bus 2
.
cargo compartment fire extinguishing powered by the hot battery bus.
Cargo Compartment Smoke Detection
The forward and aft cargo compartments each have smoke detectors in a dual loop configuration. Normally, both detection loops must sense smoke to cause an alert. These loops function in the same manner as the engine overheat/fire detection loops.
Cargo Compartment Fire Warning
The indications of a cargo compartment fire are:
.
the fire warning bell sounds
.
both master FIRE WARN lights illuminate
.
the FWD/AFT cargo fire warning light(s) illuminates.
Copyright . The Boeing Company. See title page for details. Copyright . The Boeing Company. See title page for details.
8.20.6 June 1, 2005
Lavatory Fire Protection
Lavatory fire protection consists of these systems:
.
lavatory smoke detection
.
lavatory fire extinguishing (heat activated).
Lavatory Smoke Detection
The lavatory smoke detection system monitors for the presence of smoke. When smoke is detected:
.
an aural warning sounds
.
the red alarm indicator light on the lavatory smoke detector panel
illuminates.
There is no flight deck indication. When smoke is no longer present the system automatically resets. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：737NG机组操作手册Flight Crew Operations Manual FCOM 2(131)
