2-27. Friction Lock Knobs.
switch placarded TEST SWITCH FIRE DETECTION -
OFF, 1, 2, 3, on the control pedestal, is provided to test
Four friction lock knobs are located on the control
pedestal to adjust friction drag for the engine and
checkout, battery power must be on and the FIRE
DETECTOR circuit breaker must be in. Switch position
levers, one below the condition levers, and two under
1, checks area forward of the air intake of each nacelle,
the power levers. When a knob is rotated clockwise,
including circuits to the cockpit alarm and indication
friction restraint is increased opposing movement of the
devices. Switch position 2, checks the circuits for the
affected lever as set by the pilot. Counterclockwise
upper accessory compartment of each nacelle. Switch
rotation of a knob will decrease friction drag thus
position 3, checks the circuits for the lower accessory
permitting free and easy lever movement.
compartment of each nacelle. Each numbered switch
FRICTION LOCK placards are located on the pedestal
position will initiate the cockpit alarm and indications
2-28. Engine Fire Detection System.
2-29. Oil Supply System.
A flame surveillance system is installed on each
a. The engine oil tank is integral with the air-inlet
engine to detect external engine fire and provide alarm
casting located forward of the accessory gearbox. Oil
to the pilot. Both nacelles are monitored, each having a
for propeller operation, lubrication of the reduction
control amplifier and three detectors. Electrical wiring
gearbox and engine bearings is supplied by an external
connects all sensors and control amplifiers to DC power
line from the high pressure pump. Two scavenge lines
and to the cockpit audio and visual alarm units. In each
return oil to the tank from the propeller reduction
nacelle, one detector monitors the forward nacelle, a
gearbox. A non-congealing external oil cooler keeps the
second monitors the upper accessory area, and a third
engine oil temperature within the operating limits. The
the lower accessory area.
capacity of each engine oil tank is 9.2 quarts and
includes an expansion space of 0.72 quarts. The total
system capacity for each engine, which includes the oil
sensed by the detector which monitors the area of origin.
tank, oil cooler, lines, etc., is 14 quarts - of which 6
quarts are usable. The oil level is indicated by a dipstick
amplifier which causes signal power to be sent to cockpit
attached to the oil filler cap. For oil grade, specification
alarms. An activated surveillance system will return to
the standby state after the fire is out. The system
includes a functional test switch and has circuit
b. The oil system of each engine is coupled into a
protection through the FIRE DETECTOR circuit breaker.
heat exchanger unit (radiator) of fin-and-tube design.
These exchanger units are the only airframe mounted
b. Warning of internal nacelle fire is provided as
part of the oil system and are attached to the nacelles
follows: A warning horn sounds in the cockpit;
below the engine air intake. Each heat exchanger
simultaneously the red MASTER WARNING lights on
incorporates a thermal bypass which assists in
the instrument panel start flashing. These alarms are
maintaining oil at the proper temperature range for
FIRE L ENG or FIRE R ENG light also on the
2-30. Engine Chip Detection System.
protected by a single 3-ampere circuit breaker,
placarded FIRE DETECTOR, located on the right
A magnetic chip detector is installed in the bottom of
each engine reduction gearbox to warn the pilot of oil
c. An erroneous indication of engine fire may be
is an electrically insulated gap immersed in the oil
encountered if an engine cowling is not closed properly,
functioning as a normally-open switch. If a large metal
or if the aircraft is headed toward a strong external light
chip or a mass of small particles bridge the detector gap
source. In this circumstance, close the cowling and/or
a circuit is completed, sending a signal to illuminate an
change the aircraft heading away from the light source.
annunciator panel yellow light placarded L or R CHIP
d. Fire detection system test switch.