Beechcraft C-12C Operator And Technical Reference Manual page 50

TM 1-1510-218-10
2-24. FOREIGN OBJECT DAMAGE CONTROL.
The engine has an integral air inlet screen
designed to obstruct objects large enough to damage
the compressor.
The engine anti-ice system (ice vanes)
should be on (extended) for all ground
operations to minimize ingestion of ground
debris. It may be necessary to turn off
engine anti-ice (retract ice vanes) in warm
ambient conditions to preclude exceeding
engine gas temperature limits.
2-25. ENGINE ICE PROTECTION SYSTEMS.
After the vanes have been manually
extended, they
actuated only. No electrical extension or
retraction shall be attempted as damage to
the electric actuator will result. Linkage in
the nacelle area must be reset prior to
operation of the electric system.
a. Inertial Separator.
system is built into each engine air inlet to prevent
moisture particles from entering the engine inlet
plenum under icing conditions. A movable vane and a
by-pass door are lowered into the air stream when
operating in visible moisture at +5°C or colder, by
energizing electrical actuators with the switches,
placarded ICE VANE RETRACT/EXTEND
and ICE VANE CONTROL/ON
overhead control panel.
mechanical backup system is provided, and is
actuated by pulling the T-handles just below the pilot's
subpanel, placarded ICE VANE #1 ENG and ICE
VANE #2 ENG C D1 T2
ICE VALVE # 1 ENG
160 knots or less to reduce forces for manual
extension. Normal airspeed may then be resumed.
(1) The vane deflects the ram air stream
slightly downward to introduce a sudden turn in the air
stream to the engine, causing the moisture particles to
continue on undetected, because of their greater
momentum, and to be discharged overboard.
(2) While in the icing flight mode, the
extended position of the vane and by-pass door is
indicated by green annunciator lights, #1 VANE EXT
and #2 VANE EXT.
2-34
NOTE
CAUTION
may be mechanically
An inertial separation
C D T1
T2 , located on the
Refer to Figure 2-15.
and ICE VALVE # 1 ENG and
T1 . Decrease airspeed to
(3) In the non-ice protection mode, the vane
and by-pass door are retracted out of the air stream by
placing the ice vane switches in the RETRACT
position. The green annunciator lights will extinguish.
Retraction should be accomplished at +15°C and
above to assure adequate oil cooling.
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 yellow #1
VANE FAIL or #2 VANE FAIL light illuminates on the
caution/advisory panel.
backup system should be used. When the vane is
successfully positioned with the manual system, the
yellow annunciator lights will extinguish.
manual system use, the electric motor switch position
must match the manual handle position for a correct
annunciator readout.
b. Engine Air Inlet Deice
heat is utilized for heating the engine air inlet lips. Hot
exhaust is picked up by a scoop inside each engine
exhaust stack and plumbed downward to connect into
each end of the inlet lip. Exhaust flows through the
inside of the lip downward to the bottom where it is
plumbed out through the bottom of the nacelle. No
shut-off or temperature indicator is necessary for this
system.
c. Engine Air Inlet Deice
facing into the exhaust flow of the engine's left exhaust
stack, diverts a small portion of the engine exhaust
gases to the engine air inlet anti-ice lip. The gases are
circulated through the engine air inlet anti-ice lip and
then exhausted through a duct to the engine's right
A
exhaust stack. The continuous flow of hot engine
exhaust gases heats the engine air inlet anti-ice lip,
preventing the formation of ice.
d. 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 pneumatic fuel control line is
protected against
automatically turned on for all engine operations.
2-26. ENGINE FUEL CONTROL SYSTEM.
C D The basic engine fuel system consists of an
engine driven fuel pump, a fuel control unit, a fuel flow
divider, a dual fuel manifold and 14 fuel nozzles. The
fuel flow divider acts as a drain valve to clear residual
fuel after engine shutdown.
The vanes
In this event, the manual
C D . Engine exhaust
T . A small duct,
ice. Fuel control
During
heat is