T The basic engine fuel system consists of an
engine driven fuel pump, a fuel control unit, a dual fuel
manifold, 14 fuel nozzles, and a fuel purge system.
The fuel purge system forces residual fuel from the
manifolds to the combustion chamber, where it is
a. One fuel control unit is on the accessory case
of each engine. This unit is a hydro-mechanical
metering device, which determines the proper fuel
schedule for the engine to produce the amount of
power requested by the relative position of its power
lever. The control of developed engine power is
accomplished by adjusting the engine compressor
turbine (N1) speed. N1 speed is controlled by varying
the amount of fuel injected into the combustion
chamber through the fuel nozzles. Engine shutdown is
accomplished by moving the appropriate condition
lever to the full aft, FUEL CUTOFF position, which
shuts off the fuel supply.
2-27. POWER LEVERS.
Moving the power levers into reverse range
without the engines running may result in
Two power levers are located on the control
pedestal, Figures 2-7 and 2-9. These levers regulate
power in the reverse, idle, and forward range, and
operate so that forward movement increases engine
power. Power control is accomplished through
adjustment of the N1 speed governor in the fuel control
unit. Power is increased when N1 RPM is increased.
The power levers also control propeller reverse pitch.
Distinct movement (pulling up and then aft on the
power lever) by the pilot is required for reverse thrust.
Placard beside the lever travel slots reads POWER.
forward. Lower travel range is marked IDLE / LIFT
and REVERSE. A placard below the lever slots reads,
CAUTION REVERSE ONLY WITH ENGINES
2-28. CONDITION LEVERS.
Two condition levers are located on the control
pedestal. Each lever starts or stops the fuel supply,
and controls the idle speed for its engine. The levers
have three placarded positions: FUEL CUTOFF, LO
IDLE, and HIGH IDLE. In the FUEL CUTOFF
position, the condition lever controls the cutoff function
of its engine-mounted fuel control unit. From LO IDLE
to HIGH IDLE, they control the governors of the fuel
control units to establish minimum fuel flow levels. LO
IDLE position sets the fuel flow rate to attain 52% ±
2% C D ; 56-58% T , (at sea level) minimum N1 and
HIGH IDLE position sets the rate to attain 70%
minimum N1. The power lever for the corresponding
engine can select N1 from the respective idle setting to
maximum power. An increase in low idle N1 will be
experienced at high field elevation.
2-29. FRICTION LOCK KNOBS.
Four friction lock knobs are located on the
control pedestal to adjust friction drag. Refer to
Figures 2-7 and 2-9. One knob is below the propeller
levers, one below the condition levers, and two under
the power levers. When a knob is rotated clockwise,
friction restraint is increased opposing movement of
Counterclockwise rotation of a knob will decrease
friction drag thus permitting free and easy lever
movement. Two FRICTION LOCK placards are
located on the pedestal adjacent to the knobs.
2-30. ENGINE FIRE DETECTION SYSTEM C D T1 .
A flame surveillance system is installed on each
engine to detect external engine fire and provide alarm
to the pilot. Both nacelles are monitored, each having
a control amplifier and three detectors. Electrical
wiring connects all sensors and control amplifiers to dc
power and to the cockpit visual alarm units. In each
nacelle, one detector monitors the forward nacelle, a
second monitors the upper accessory area, and a third
the lower accessory area.
a. Fire emits an infrared radiation that will be
sensed by the detector, which monitors the area of
origin. Radiation exposure activates the relay circuit of
a control amplifier, which causes signal power to be
sent to cockpit warning systems. An activated
surveillance system will return to the standby state
after the fire is out. The system includes a functional
b. Warning Of Internal Nacelle Fire.
(1) The red MASTER WARNING light on the
illumination of a red warning light in the appropriate fire
control T-handle, placarded FIRE PULL. Fire detector
circuits are protected by a single 5 -ampere circuit
breaker, placarded FIRE DETR located on the
overhead circuit breaker panel, Figure 2-16.