TM 55-1510-222-10
Table 2-1. Engine Fire Extinguisher Gage Pressure
TEMP°C
-40
-29
-18
-06
04
16
27
38
48
PSI
190
220
250
290
340
390
455
525
605
to
to
to
to
to
to
to
to
to
240
275
315
365
420
480
550
635
730
BT0194
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
(table 2-1).
2-27. OIL SUPPLY SYSTEM.
CAUTION
Maximum allowable oil consumption
is .3 lb/hr (.45 gallons) per 10 hours of
engine operation.
a. The engine oil tank is integral with the air-inlet
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
2.5 U.S. gallons. The total system capacity for each
engine, which includes the oil tank, oil cooler, lines, etc.,
is approximately 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 an
oil cooler unit (radiator) of fin-and-tube design. These
oil cooler units are the only airframe mounted part of the
oil system and are located in the lower aft nacelles
below the engine air intake. Each oil cooler
incorporates a thermal bypass valve which assists in
maintaining oil at the proper temperature range for
engine operation.
2-28. ENGINE IGNITION SYSTEM.
a. Description. The basic ignition system consists
of a solid state ignition exciter unit, two igniter plugs, two
shielded ignition cables, pilot controlled ignition and
engine start switches and the auto ignition switches.
Placing either ENG START switch to START -
IGNITION position will cause the respective engine to
motor, and igniter plugs to spark, igniting the fuel/air
mixture sprayed into the combustion chamber by the
fuel nozzles. The ignition system is activated for ground
and air starts, but is switched off after combustion light
up.
b. Ignition and Engine Starter Switches. Two
three-position toggle switches, placarded #1 or #2 ENG
START, are located in the overhead control panel (fig.
2-13). These switches will initiate starter motoring and
ignition in the START IGNITION position, or will motor
the engine in the STARTER ONLY position. The
START IGNITION switch position completes the starter
circuit for engine rotation, energizes the igniter plugs for
fuel combustion, and activates the #1 IGN ON or #2
IGN ON annunciator on the annunciator panel. In the
center position the switch is OFF. Two 5-ampere circuit
breakers on the overhead circuit breaker panel,
placarded IGNITOR CONTR #1 and #2, protect ignition
circuits. Two 5-ampere circuit breakers on the overhead
circuit breaker panel, placarded START CONTR #1
and #2, protect starter control circuits (fig. 2-6).
2-29. AUTO IGNITION SYSTEM.
If armed, the auto ignition system automatically
provides combustion re-ignition of either engine, should
an accidental flameout occur. The system is not
essential to normal engine operation, but is used to
reduce the possibility of power loss due to icing or other
conditions. Each engine has a separate auto ignition
control switch and a green annunciator placarded #1
IGN ON or #2 IGN ON, on the annunciator panel. Auto
ignition is accomplished by energizing both igniter plugs
in each engine.
NOTE
The system should be turned OFF
during extended ground operation to
prolong the life of the igniter plugs.
a. Auto Ignition Switches. Two switches, located
in the overhead control panel (fig. 2-13), each placarded
AUTO IGNITION - ARM control the
2-27
