2-20. ENGINE ICE PROTECTION SYSTEMS.
a. Inertial Separator.
After the ice vanes have been manually
extended, they may be mechanically actu-
ated only. No electrical extension or
retraction shall be attempted as damage
to the actuator may result. Linkage in the
nacelle area must be reset prior to opera-
tion of the electric system.
An inertial separation system is built into each
engine air inlet to prevent moisture particles from
entering the engine inlet plenum under icing condi-
tions. A movable vane and a bypass door are low-
ered into the airstream when operating in visible
moisture at 5°C or colder, by energizing electrical
actuators with the switches, placarded ICE VANE -
RETRACT - EXTEND, located on the overhead
control panel. A mechanical backup system is pro-
vided, and is actuated by pulling the T-handles just
below the pilots subpanel placarded ICE VANE -
No. 1 ENG - No. 2 ENG. Decrease airspeed to 160
knots or less to reduce forces for manual extension.
Normal airspeed may then be resumed.
(1.) The vane deflects the ram airstream
slightly downward to introduce a sudden turn in the
airstream to the engine, causing the moisture parti-
cles to continue on undeflected, because of their
greater momentum, and to be discharged overboard.
(2.) While in the icing flight mode, the
extended position of the vane and bypass door is
indicated by green annunciator lights, No. 1 VANE
EXT and No. 2 VANE EXT.
(3.) In the non-ice protection mode, the
vane and bypass door are retracted out of the air-
stream by placing the ice vane switches in the
RETRACT position. The green annunciator lights
will extinguish. To assure adequate oil cooling,
retraction should be accomplished at 15°C and
above. The vanes should be either extended or
retracted; there are no intermediate positions.
(4.) If for any reason the vane does not
attain the selected position within 15 seconds, a yel-
low No. 1 VANE FAIL or No. 2 VANE FAIL light
illuminates on the caution/advisory panel. In this
event, the manual backup system should be used.
When the vane is successfully positioned with the
manual system, the yellow annunciator lights will
extinguish. During manual system use, the electric
motor switch position must match the manual han-
dle position for a correct annunciator readout.
b. Engine Air Inlet Deice System.
Description. Hot engine exhaust gas is
utilized for heating the air inlet lips to prevent the
formation of ice. Hot exhaust gas is picked up inside
each engine exhaust stack and carried by plumbing
to the inlet lip. The gas flows through the inside of
the lip to the bottom where it is allowed to escape.
(2.) Fuel heater.
An oil-to-fuel heat
exchanger, located on the engine accessory case,
operates continuously and automatically to heat the
fuel sufficiently to prevent ice from collecting in the
fuel control unit. Each fuel control unit is protected
against ice. Fuel control heat is automatically turned
on for all engine operations.
2-21. ENGINE FUEL CONTROL SYSTEM.
a. Description. The basic engine fuel system
consists of an engine driven fuel pump, a fuel con-
trol unit, a fuel flow divider, a dual fuel manifold
and fourteen fuel nozzles. The fuel flow divider acts
as a drain valve to clear residual fuel after engine
b. Fuel Control Unit. One fuel control unit is
mounted on the accessory case of each engine. This
unit is a hydro-pneumatic metering device which
determines the proper fuel schedule for the engine to
produce the amount of power requested by the rela-
tive position of its power lever. The control of devel-
oped 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 noz-
zles. Engine shutdown is accomplished by moving
the appropriate condition lever to the full aft FUEL
CUTOFF position, which shuts off the fuel supply.
2-22. POWER LEVERS.
Moving the power levers into reverse
range without the engines running may
result in damage to the reverse linkage
Two power levers are located on the control
pedestal (fig. 2-7). 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