CAE SimuFlite Citation Bravo, Pilot Training Manual

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Fire Protection
Citation Bravo
Developed for Training Purposes
5D-5
March 2009
Engine Fire
Detection
System
The fire detection system identifies a
fire or overheat condition in either
engine nacelle. Components of the
system include a detection sensor
cable (loop), a fire detection control
unit, and an ENGINE FIRE switch-
light for each engine.
If an engine fire or overheat condi-
tion occurs, the fire detection loop
directs a signal to the fire detection
control unit. The control unit illumi-
nates the corresponding ENGINE
FIRE switchlight on the glareshield.
When pressed, the same switchlight
arms the extinguishing system.
All detection, extinguishing, and test
features are electrically powered
from the Main DC buses requiring
either external power, the battery
switch in BATT, or a generator on
the line for operation.
Fire Detection Loop
Each engine nacelle houses a 188-
cubic inch heat sensing loop
(Figure
5D-1)
of flexible, stainless steel
cable contains a 28 V DC energized
inner wire centered in a highly com-
pacted, metal oxide semiconductor
material. The hermetically sealed
cable has a fire-proof connector at
each end.
Each sensor loop connects to its
respective control unit in the tailcone
on the aft pressure bulkhead. Normal
DC power supplies the system
through the 2-amp L and R FIRE
DET CBs. The Left Main Extension
bus feeds the R FIRE DET CB,
while the Right Crossover bus feeds
the L FIRE DET CB via the Right
Main Extension bus.
As the temperature increases, the
semi-conductor resistance (ohmage)
decreases. At approximately 500 to
560°F, resistance (ohms) drops to a
value allowing a signal from the
inner wire to flow to the outer casing
to close a circuit at the control unit.
Fire Control Unit
Two fire detection control units, one
for each engine, are in the aft fuse-
lage section and accessible through
the tailcone compartment door.
5D-1