TM 55-1510-220-10
is headed toward a strong external light source. In this
circumstance, change the aircraft heading to enable a
valid system check.
2-27. ENGINE FIRE EXTINGUISHER SYSTEM.
a.
Description. The fire extinguisher system utilizes
an explosive squib, connected to a valve which, when
opened, allows the distribution of the pressurized
extinguishing agent through a plumbing network of spray
nozzles strategically located in the fire zones of the
engines.
b.
Fire Pull Handles. The fire control T-handles,
which are used to arm the extinguisher system are
centrally located on the pilot's instrument panel (fig. 2-
30), immediately below the glareshield. These controls
receive power from the hot battery bus. The fire detection
system will indicate an engine fire by illuminating the
master fault warning annunciator on the pilot's and
copilot's glareshield and the respective NO. 1 FIRE PULL
or No. 2 FIRE PULL annunciators in the fire control T-
handles. Pulling the fire control T-handle will electrically
arm the extinguisher system and close the fuel firewall
shutoff valve for that particular engine. This will cause
the red annunciator in the PUSH TO EXTINGUISH switch
and the respective red No. 1 FUEL PRESS or No. 2
FUEL PRESS annunciator on the warning annunciator
panel to illuminate. Pressing the lens of the PUSH TO
EXTINGUISH switch (after lifting one side of its spring-
loaded clear plastic guard) will fire the squib, expelling all
the agent in the cylinder at one time. The respective
yellow caution annunciator, No. 1 EXTGH DISCH or No.
2 EXTGH DISCH on the caution/advisory annunciator
panel will illuminate and remain illuminated, until the
squib is replaced.
c.
Fire Extinguisher System Test Switch. A rotary
test switch, placarded FIRE PROTECTION TEST, is
located on the copilot's subpanel. The test functions,
placarded EXTGH No.1 No.2, are arranged on the left
side of the switch and provide a test of the pyrotechnic
cartridge circuitry. During preflight, the pilot should rotate
the test switch through the two positions and verify the
illumination of the green SQUIB OK light on the PUSH
TO EXTINGUISH switch and the corresponding yellow
No.1 or No.2 EXTGH DISCH light on the caution/advisory
annunciator panel.
d.
Fire
Extinguishing
System
Supply
Cylinder
Gages. A gage, calibrated in PSI, is mounted on each
supply cylinder for determining the level of charge and
should be checked during preflight (table 2-1).
2-28. OIL SUPPLY SYSTEM.
CAUTION
Maximum
allowable
oil
consumption is one quart per 10
hours of engine operation.
a.
The engine oil tank is integral with the airinlet
casting located forward of the accessory gearbox. Oil for
propeller operation, lubrication of the reduction gearbox
and engine bearings is supplied by an external line from
the high pressure pump. Two scavenge lines return oil to
the tank from the propeller reduction gearbox. A non-
congealing external oil cooler keeps the engine oil
temperature within the operating limits. The capacity of
each engine oil tank is 2.3 U.S. gallons. The total system
capacity for each engine, which includes the oil tank, oil
cooler, lines, etc., is 3.5 U.S. gallons. The oil level is
indicated by a dipstick attached to the oil filler cap. Oil
grade, specification and servicing points, are described in
Section IX, Servicing.
b.
The oil system of each engine is coupled to a
heat exchanger unit (radiator) of fin-and-tube design.
These exchanger units are the only airframe mounted part
of the oil system and are attached to the nacelles below
the engine air intake. Each heat exchanger incorporates
a thermal bypass which assists in maintaining oil at the
proper temperature range for engine operation.
Change 2 2-25
