a 4 second inflation begins in the horizontal stabilizer,
stabilon, and taillet boots. When these boots have
inflated and deflated, the cycle is complete.
(3) If the switch is held in the MANUAL position,
the boots will inflate simultaneously and remain inflated
until the switch is released. The switch will return to the
OFF position when released. After the cycle, the boots
will remain in the vacuum hold down condition until
again actuated by the switch.
(4) Either engine is capable of providing
sufficient bleed air for all requirements of the surface
deice system. Check valves in the bleed air and
vacuum lines prevent backflow through the system
during single engine operation. Regulated pressure is
PRESSURE, located on the center subpanel.
(5) Under conditions where one bleed air
source is inoperative, sufficient bleed air pressure for
deice boot inflation may not be available. Prior to deice
boot inflation, check the regulated bleed air pressure
gage for a minimum of 16 PSL If insufficient pressure
exists, increasing engine N1 and/or decreasing aircraft
altitude will increase bleed air pressure.
ANTENNA DEICING SYSTEM.
Description. The antenna deicing system
removes or prevents ice accumulation on the mission
antennas. Pressure regulated bleed air from both
engines supply pressure to inflate the boots. To assure
operation of the system, in the event of failure of one
engine, a check valve is incorporated in the bleed air
line from each engine to prevent loss of pressure
through the compressor of the inoperative engine.
Inflation and deflation phases are controlled by
To ensure adequate bleed air pressure to
the deice boots, do not simultaneously
actuate surface and antenna deice systems
in the manual mode.
Under conditions where one bleed air
source is inoperative, sufficient bleed air
pressure for deice boot inflation may not be
available. Prior to deice boot inflation,
check the regulated bleed air pressure gage
for a minimum of 16 PSI. If insufficient
pressure exists, increasing engine N, and/or
decreasing aircraft altitude will increase
bleed air pressure.
Antenna Deice System Switch. The antenna
deice system is controlled by a switch placarded
ANTENNA, MANUAL SINGLE CYCLE AUTO located on
the overhead control panel (fig. 2-13). The switch is
spring loaded to return to the off position from the
SINGLE CYCLE AUTO or MANUAL position When the
switch is set to the SINGLE CYCLE AUTO position, the
system will run through one timed inflation-deflation
cycle. When the switch is held in the MANUAL position
the boots will inflate and remain inflated until the switch
Operation. Deice boots are intended to remove
ice after it has formed rather than prevent its formation.
For the most effective deicing operation, allow at least
1/8 to 1/4 inch of ice to form on the boots before
attempting removal. Very thin ice may crack and cling
to the boots instead of shedding.
Never cycle the system rapidly, this may
cause the ice to accumulate outside the
contour of the inflated boots and prevent ice
FORWARD INTEROPERABLE DATA LINK
ANTENNA RADOME ANTI-ICE.
The forward interoperable data link antenna radome
anti-ice system utilizes engine bleed air to prevent the
formation of ice on the radome. The system is
controlled by a switch placarded RADOME ON, located
on the overhead control panel (fig. 2-13). The circuit is
protected by a 7.5ampere circuit breaker placarded
RADOME ANTI-ICE, located on the overhead circuit
breaker panel (fig. 2-7).
PROPELLER ELECTRIC DEICE SYSTEM.
Description. The propeller electric deice system
includes electrically heated deice boots, slip rings and
brush block assemblies, a timer for automatic operation,
ammeter, circuit breakers for left and right propeller and
control circuit protection, and two switches located on
the overhead control panel (fig. 2-13), for automatic or
manual control of the system.
Automatic Operation. The two position switch
located on the overhead control panel, placarded PROP
AUTO ON, is provided to activate the automatic system.
Upon placing the switch to the ON position, the timer
diverts power through the brush block and slip ring to all
heating elements on one propeller. Subsequently, the