valve as well. A small, red shutoff valve light,
commonly called a “pinhead light,” will illu-
minate to indicate the FIRE warning light has
been depressed. Power is also applied to arm the
respective amber ARMED lights (Figure 8-4).
Depressing an illuminated ARMED light mo-
mentarily applies DC power to an explosive
cartridge, which discharges the contents of a
bottle to the selected engine. Depressing the
adjacent ARMED light fires the remaining
bottle to the same engine. Depressing the FIRE
warning light a second time disarms the sys-
tem (ARMED lights go out), opens the hy-
d r a u l i c a n d f u e l s h u t o f f v a l v e s , a n d
extinguishes the pinhead light.
Airplanes Without Glareshield
Warning Lights
Opening the red guard and actuating a FIRE-
WALL SHUTOFF switch (LH or RH) selects
the engine to which fire-extinguishing agent
is to be applied. It also applies 28 VDC to
close the hydraulic and fuel shutoff valves
(Figure 8-5) and arms the No. 1 and No. 2 dis-
charge switches.
Depressing the No. 1 discharge switch fires
a bottle to the selected engine. If a second
charge of extinguishing agent is desired, de-
pressing the No. 2 discharge switch fires the
r e m a i n i n g b o t t l e t o t h e s a m e e n g i n e .
Returning the guarded FIREWALL SHUT-
OFF switch to the off position opens the hy-
draulic and fuel shutoff valves and disarms
the fire-extinguishing system.
8-4
FOR TRAINING PURPOSES ONLY
LEARJET 20 SERIES PILOT TRAINING MANUAL
FlightSafety
international
SHUTOFF VALVE (PINHEAD) LIGHT
THERMAL
DISCHARGE INDICATOR
MANUAL
DISCHARGE INDICATOR
ARMED
FUEL SHUTOFF
VALVE
HYDRAULIC
SHUTOFF VALVE
ARMED
FIRE
LH
CONTAINER
RELIEF VALVE
RELIEF VALVE
PRESSURE GAGE
PRESSURE GAGE
RH NACELLE
LH NACELLE
ARMED
FUEL SHUTOFF
VALVE
*BLEED-
AIR VALVE
*BLEED-
AIR VALVE
HYDRAULIC
SHUTOFF VALVE
ARMED
FIRE
RH
CONTAINER
TWO-WAY
CHECK
VALVES
*SNS 24-350 AND SUBSEQUENT AND
25-227 AND SUBSEQUENT
ENGINE EXTINGUISHING
MANUAL DISCHARGE
THERMAL DISCHARGE
LEGEND
Figure 8-4.
Engine Fire-Extinguishing System (Airplanes with
Glareshield Warning Lights)