responder unit contains two sets of contacts: a set of
integrity switch contacts, for continuity test functions of
the fire detection circuitry; and a set of alarm switch
contacts, which complete the circuit to activate the fire
warning system when the detector (sensing tubing)
senses an overtemperature condition in critical areas
around the engine. The detector is dual functioning and
responds to overall "average" temperature, or a highly
localized "discrete" temperature, caused by flames or
hot gases. Both the average and discrete temperatures
are preset, and cannot be adjusted in the field.
The sensor tubing consists of an outer tube filled with an
inert gas, and an inner gas filled core that is filled with
an active gas. The gases within the tube form a
pressure barrier that keeps the contacts of the responder
integrity switch closed for fire alarm continuity test
functions. As the temperature around the sensing cable
increases, the gases within the tube begin to expand.
When the pressure from the expanding gases reaches a
preset point, the contacts of the responder alarm switch
close, activating the respective fire warning system.
Warning System. The fire warning system
consists of two lenses, placarded # 1 FIRE PULL and #
2 FIRE PULL located in the T handles below the
glareshield, two MASTER WARNING annunciators
located in opposite sides of the glareshield, and two
compartments. If the detector should develop a leak,
the loss of gas pressure would allow the integrity switch
to open and signal a lack of detector integrity.
Testing. Testing system integrity, availability of
power, and the annunciators (#1 and #2 FIRE PULL and
MASTER WARNING), is accomplished by two switches
located on the copilot's subpanel. The switches are
placarded ENG FIRE TEST, DET OFF EXT, LEFT and
RIGHT. When either (LEFT or RIGHT) switch is placed
in the DET position, electrical current flows from a 5-
ampere circuit breaker placarded FIRE DEIR located on
the overhead circuit breaker panel, through the engine
fire detector circuitry to the integrity switch contacts in
the respective responder unit, causing the respective
annunciators to illuminate. If the circuit breaker opens,
the system will not operate during a test, or activate the
overtemperature condition. The system may be tested
either before, after, or in flight as desired.
ENGINE FIRE EXTINGUISHER SYSTEM.
Description. The engine fire extinguisher
system (fig. 2-15), consists of a supply cylinder, an
explosive squib, and valve located in each of the main
gear wheel wells. A gage calibrated in PSI is provided
on each supply cylinder for determining the level of
charge. The extinguishing agent charge level should be
checked during each preflight When fired, the explosive
squlb opens the valve, releasing all of the pressurized
extinguishing agent into a plumbing network The
strategically located in the probable fire areas of the
Operation. Fire control T handles used to arm
the extinguisher system are centrally located on the
instrument panel, immediately below the glareshield (fig.
2-16). These controls receive power from the hot
battery bus. The fire detector system will indicate an
engine fire by illuminating the MASTER WARNING
annunciators on the glareshield and the respective #1 or
#2 I;IRE PULL annunciators in the fire control T handles.
Pulling the fire control T handle will electrically arm the
extinguisher system and close the firewall shutoff valve
for that particular engine. This will cause the
annunciator in the PUSH TO EXTINGUISH switch and
the respective #1 or #2 FUEL PRESS annunciator on
the warning annunciator panel to illuminate. Pressing
the lens of the PUSH TO EXTINGUISH fire switch will
fire the squib, expelling all the agent in the cylinder at
one time. A hinged plastic guard covers the PUSH TO
EXTINGUISH fire switch to prevent inadvertently
actuating the fire extinguish switch squib circuit The
respective caution annunciator, # 1 and # 2 EXTGH
DISCH on the caution/advisory annunciator panel and
the MASTER CAUTION annunciator on the glareshield
will illuminate and remain illuminated, regardless of the
master switch position, until the squib is replaced.
Testing. The test switches located on the
copilot's subpanel (fig. 2-6), are placarded ENG FIRE
TEST, DET OFFEXT, LEFT and RIGHT , and provide a
test of the fire detection and extinguisher circuitry.
When either of the switches is placed in the EXI'
position, the corresponding PUSH TO EXTINGUISH,
SQUIB OK, and EXTGH DISCH annunciators should
illuminate. The system may be tested either before,
after, or in flight as desired.
A gage calibrated in PSI is mounted on each
extinguishing agent supply cylinder for determining the
level of charge and should be checked during preflight
OIL SUPPLY SYSTEM.
Maximum allowable oil consumption is one quart in
5 hours of engine operation.
a. The engine oil tank is integral with the air-inlet asting
located forward of the accessory gearbox. Oil for