Table 2-1. Engine Fire Extinguisher Gage Pressure
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
noncongealing, external oil cooler keeps the engine oil
temperature within 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, specifications, and
servicing points, are described in Section XII, Servicing.
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 IGNITION SYSTEM.
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 (fig.
2-13). 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
Ignition and Engine Starter Switches. Two
threeposition toggle switches, placarded # 1 or # 2 ENG
START, are located on 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 respective # 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.
AUTO IGNITION SYSTEM.
If armed, the auto ignition system automatically
energizes both igniter plugs 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
(fig. 2-13), 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.
The system should be turned OFF during
extended ground operation to prolong the
life of the igniter plugs.
Auto Ignition Switches. Two switches, located
on the overhead control panel (fig. 2-13), each
placarded AUTO IGNITION ARM, control the auto
ignition systems. The ARM position initiates a readiness
mode for the auto ignition system of the corresponding
engine. The system is disarmed when in the off position
Each circuit is protected by the corresponding START
CONTR # 1 or # 2, 5-ampere circuit breaker on the
overhead circuit breaker panel (fig. 2-7).
Auto Ignition Annunciators. If an armed auto
ignition system changes from a ready condition to an
operating condition (energizing the igniter plugs in the
engine) the corresponding engine's green annunciator
will illuminate. The annunciator is placarded # l IGN ON
or #2 IGN ON and indicates that the igniters are
energized. The auto ignition system is triggered from a
ready condition to an operating condition when engine
torque drops below approximately 20% Therefore, when
an auto ignition system is armed, the igniters will be
energized continuously during the time when an engine
is operating at a level below approximately 20% torque.
The auto ignition annunciators are protected by the 5-
ampere IGNITOR CONTR # 1 or # 2 circuit breakers,
located on the overhead circuit breaker panel (fig. 2-7).