2-29. ENGINE CHIP DETECTION SYSTEM.
A magnetic chip detector is installed in the bottom
of each engine nose gearbox to warn the pilot of oil
contamination and possible engine failure. The sensor is
an electrically insulated gap immersed in the oil,
functioning as a normally-open switch. If a large metal
chip or a mass of small particles bridge the detector gap,
a circuit is completed, sending a signal to illuminate a red
annunciator panel indicator light placarded #1 or #2 CHIP
DETR and the MASTER WARNING lights. Chip detector
circuits are protected by two 5-ampere circuit breakers,
placarded CHIP DETR #1 and #2 on the overhead circuit
breaker panel (fig. 2-26).
2-30. ENGINE IGNITION SYSTEM.
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 ENG AUTO IGN switch. Placing an
IGNITION AND ENGINE START switch to ON (forward)
will cause the respective 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
One three-position toggle switch for each engine,
located on the overhead control panel, will initiate starter
motoring and ignition in the ON/ ENG START position, or
will motor the engine in the STARTER ONLY (aft) position
(fig. 2-18). The switches are placarded #1 ENG START
or #2 ENG START to designate the appropriate engine.
The ON switch position completes the starter circuit for
engine rotation, energizes the igniter plugs for fuel
combustion, and activates the IGN ON light on the
annunciator panel. At 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 5ampere circuit breakers on
the overhead circuit breaker panel, placarded START
CONTR #1 and #2, protect starter control circuits (fig. 2-
2-31. AUTO IGNITION SYSTEM.
If armed, the auto ignition system automatically
provides combustion re-ignition of either engine should
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 indicator light placarded #1 or #2 IGN ON, on
the annunciator panel. Auto ignition is accomplished by
energizing the two igniter plugs in each engine.
The system should be turned OFF
during extended ground operation
to prolong the life of the igniter
Auto Ignition Switches. Two switches placarded
ENG AUTO IGN #1 or #2, control the auto ignition
systems. The ARM position initiates a readiness mode
for the auto ignition system of the corresponding engine.
The OFF position disarms the system. Each switch is
protected by a corresponding START CONTR #1 or #2 5-
ampere circuit breaker on the overhead circuit breaker
panel (fig. 2-26).
Auto Ignition Lights. If an armed auto ignition
system changes from a ready condition to an operating
condition (energizing the igniter plugs in the engine) a
illuminate. The annunciator panel light is placarded #1 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 lights are protected by 5-ampere
IGNITOR CONTR #1 or #2 circuit breakers, located on
the overhead circuit breaker panel (fig. 2-26).
2-32. ENGINE STARTER-GENERATORS.
One start-generator is mounted on each engine
accessory drive section. Each is able to function either as
a starter or as a generator. In the starter function, 28
volts DC is required to power rotation. In the generator
function, each unit is capable of 400 amperes DC output.
Each starter circuit is protected by a 5-ampere circuit
breaker placarded START CONTR, located on the
overhead circuit breaker panel. An automatic starter cut-
off is installed in each starter-generator to provide
automatic termination of the start cycle at approximately
40% NI. This rotational speed is sensed by a magnetic
sensor internal to the starter-generator. For additional
information on the starter-generator system refer to
2-33. ENGINE INSTRUMENTS.
The engine instruments are
near the center of the instrument panel (fig. 2-28).