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available and will activate both the STALL
warning legends and aural warning tone.
When an overtemperaturec ondition occurs,t he EGT
display rises above 940 “C, the warning chevrons begin
to flash, and a signal from the EGT indicator activates
the STALL warning legend and the aural tone. The
overtemperaturew arning systemi s checkedb y the pilot
during prestart as part of the MASTER TEST check in
INST test.
ORIGINAL 2-30
NAVAIR 0%F14AAD-1
2.12 FIRE DETECTION SYSTEM
The fire detection system provides a cockpit indication
of fue or overheating in either engine compartment.
There is a separates ystemf or eache nginec ompartment,
each consisting of a thermistor-type sensing loop moaitoed
by a transistorized control unit. The system is
powered by 28 volts from the essential dc No. 1 bus.
Figure 2-27 is a functional schematic of the system.
The sensing loop for each engine compartment consists
of a 45foot continuous tubular element routed
throughout the entire length of the engine compartment
on both sides above the nacelle door hinge line. The tube
sheath, which is clamped in grommets to the engine
compartment structure, contains a ceramic-like thermistor
material in which are embedded two electrical
conductors; one of the conductors is grounded at both
endso f the loop. Electrical resistanceb etweent wo conductorsv
aries inversely as a function of temperaturea nd
length, so that heating of less than the full length will
require a higher temperature for the resistance to decrease
to the alarm point. The L or R FIRE warning
lights in the cockpit illuminate when the respective ea-
The tire alarm output relay to the light is a latching
type that remains in the last energized position in&
pendent of power interruptions until the fault clears.
False alarms triggered by moisture. in the sensing
element and co~ectors or by damage resulting in short
circuits or grounds in the sensing element are unlikely
because of the system design. Additionally, there is no
loss or impairment of fire detector capability from a
single break in the sensing element as long as there is no
electrical short. With two breaks in the sensing element,
the section between the breaks becomes inactive although
the remaining segment ends remain active.
Fire detection circuits in the engine compartments
detecta leak in the high-temperatured uct and illuminate
the appropriate FIRE warning light and activate the L
FIRE or R FIRE warning legend on the MFD and HUD.
The warning legend is a repeat of a discrete from the tire
detect system.
2.12.1 Fire Detection Test. An integrity test ofthe
tire detection system can be performed by selection of
FIRE DETiEXT on the pilot MASTER TEST switch.
The integrity test simultaieously checks the sensing ele
ment loops of both engine compartments for continuity
SHORT
tire sensing loop is heated to approximatel; 600 “F or
when any 6-inch section is heated to approximately
1,000 “F.
WUD AND MFD
WARNINLGE OENDS~
TEST THERnilSTOR
Figure 2-27. Fire Detection System
2-39 ORIGINAL
NAVAIR 01-Fl4AAD-1
and freedom from short circuits, and the fire alarm circuits
and FIRE warning lights for proper functioning.
Presence of a short circuit or control unit maltiction
causes the warning light to remain out. Fii detection
test is not available on the emergency generator.
2.13 FIRE EXTINGUISHING SYSTEM
The fa extinguishing system is capable of discharging
an extinguishing agent into either engine nacelle and
its accessory section. The system consists of two containers
of extinguishing agent, piping and nozzles to
route and discharge the agent, cockpit switches to activate.
the system, and advisory lights that alert the flightcrew
to a drop in system pressure beyond a predetermined
level.
The fue extinguishing agent is a clean, colorless,
odorless, and electrically nonconductive gas. It is a
low-toxicity vapor that chemically stops the combustion
process. It will not damage equipment because it leaves
no water, foam, powder, or other residue.
The retention time of an adequate concentration of
the extinguishing agent in the engine compartment will
determine probability of reignition, and, therefore, the
probability of aircraft survival. At high airspeeds,
where airflow through the engine compartment is increased,
agent retention time is reduced.
The slower the airspeed at the time the extinguisher
is fued, the higher the probability of fire extinction and
the lower the probability of reignition.
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F-14D 飞行手册 Flight Manual 1(76)