2-27. OIL SUPPLY SYSTEM.
Maximum allowable oil consumption is one quart per 5 hours of engine operation.
a. The engine oil tank is integral with the air-inlet casing located forward of the accessory gearbox. An external
line from the high-pressure pump supplies oil for propeller operation, lubrication of the reduction gearbox and engine
bearings. 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. Total system capacity for each engine, which includes the oil tank, oil cooler, lines, etc., is approximately
3.5 U.S. Gallons. A dipstick attached to the oil iller cap indicates the oil level. Oil grade, speciication and servicing
points, are described in Section XV, Servicing and Mooring.
b. The oil system of each engine is coupled to an oil cooler unit (radiator) of in-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 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 #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. 2-12).
2-29. AUTO IGNITION SYSTEM.
If armed, the auto ignition system automatically energizes both igniter plugs of either engine, should an accidental
lameout 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
a. 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. The corresponding
START CONTR #1 or #2 , 5-ampere circuit breaker on the overhead circuit breaker panel (Fig. 2-12), protects each
b. Auto Ignition Annunciators. 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 #1 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 ap-
proximately 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 annun-
ciators are protected by the 5-ampere IGNITOR CONTR #1 or #2 circuit breakers, located on the overhead circuit