787 Flight Crew Operations Manual
DO NOT USE FOR FLIGHT
Fire Protection -
System Description
Copyright © The Boeing Company. See title page for details.
8.20.4 D615Z003-TBC
APU Fire Protection
APU fire protection consists of these systems:
• APU fire detection
• APU fire extinguishing
APU Fire Detection
The APU compartment has dual fire detector loops. There is no APU overheat
detection.
Normally, both loops must detect a fire to produce a fire warning. An APU fire
warning automatically shuts down the APU.
If a fault is detected in one loop, the system automatically switches to single loop
operation. If the operating loop detects a fire, an APU fire warning occurs and the
APU shuts down.
The EICAS advisory message DET FIRE APU is displayed if the APU fire
detection system fails.
APU Fire Warning
The indications of an APU fire warning are:
• the fire bell sounds
• the master WARNING lights illuminate
• the EICAS warning message FIRE APU is displayed
• the APU fire switch fire warning light illuminates
• the APU fire switch unlocks
APU Fire Extinguishing
There is one APU fire extinguisher bottle. When the APU fire switch is pulled out,
rotating the switch in either direction discharges the extinguisher bottle into the
APU compartment. If the bottle is discharged or has low pressure:
• the APU BTL DISCH light illuminates
• the EICAS advisory message BOTTLE DISCH APU is displayed
An APU fire signal causes the APU to shutdown immediately. The APU
extinguisher bottle is automatically discharged after a 15 second delay to allow
time for the fuel valve to close.
On the ground with both engines off an APU fire signal from either APU fire
detector loop causes APU shutdown and extinguisher bottle discharge.
February 15, 2010
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