may use this panel to operate the APU fire-
bottle if a fire occurs.
In the event of an APU overheat or fire the APU
M a i n t e n a n c e Pa n e l s e n d s a s i g n a l t o t h e
Electronic Control Unit (ECU), which relays
the signal to the cockpit for an APU fire warn-
ing. The APU shutdown and agent extinguisher
discharge sequence is automatic. However,
this sequence can also be manually activated
by raising the protective cover on the “APU
FIRE” switch located on the APU Control
Panel and depressing the red FIRE PUSH but-
ton (Figure 8-9). When the FIRE PUSH but-
ton is depressed, the firebottle releases the
Halon extinguishing agent into the APU en-
closure
APU Maintenance Control Panel
The APU Maintenance Control Panel emer-
gency shutdown switch, when toggled manu-
ally, removes power from the ECU in the event
of an overheat or fire (Figure 8-10). The ECU
commands APU shutdown as a result of the
power loss. To reapply power to the ECU,
reset the “SHUTDOWN” switch.
In the event of a cockpit or cabin bleed-air duct
overheat condition, the ECS overheat relay
and temperature control relays, within the
APU Maintenance Control Panel, open and
command the ECU to shut down the APU.
APU Fire Indications
In the event an overheat or fire is detected in
the APU, the detector loop transmits a signal
to the APU maintenance panel that signals the
ECU to transmit a signal to the cockpit to alert
the operator. That signal illuminates the FIRE
PUSH switch located on the APU Control
Panel. In addition, a warning horn located in
the nose landing gear wheel well sounds to
alert ground personnel and a red “APU FIRE”
CAS warning message is posted on EICAS.
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
8-8
FOR TRAINING PURPOSES ONLY
FlightSafety
international
Figure 8-8. APU Fire Extinguisher Container and Pressure Gage
