TM 55-1510-222-10
ducts to the heating system. One outlet is just below the
pilot's windshield and the other is below the copilot's
windshield. A push-pull control, placarded DEFROST
AIR, on the pilot's subpanel, manually controls airflow to
the windshield. When pulled out, defrosting air is
ducted to the windshield. As the control is pushed in,
there is a corresponding decrease in airflow.
b.
Automatic Operation.
1.
Vent blower switches As required.
2.
Cabin temperature mode selector switch
AUTO.
3.
Cabin temperature control rheostat As
required.
4.
Cabin air, copilot air, pilot air, and defrost
air controls as required.
c.
Manual Operation.
1.
Pilot and copilot air controls In.
2.
Cabin air and defrost air controls Out
3.
Cabin air mode select switch MAN HEAT.
4.
Cold air outlets As required.
5.
Manual temperature switch as required.
d.
Manual Operation. If the automatic temperature
control should fail to operate, the temperature of defrost
air and cabin air can be controlled manually by setting
the CABIN AIR MODE SELECT switch to the MANUAL
COOL position, then using the CABIN AIR TEMP
CONTROL switch to set the desired temperature. This
control is located in the overhead control panel (fig. 2-
13).
2-52. SURFACE DEICING SYSTEM.
a. Description. Ice accumulation is removed from
each inboard and outboard wing leading edge, both
horizontal stabilizers, stabilons and tailets by the flexing
of deice boots which are pneumatically actuated.
Engine bleed air from the engine compressor is used to
supply air pressure to inflate the deice boots, and to
supply vacuum through the ejector system. A pressure
regulator protects the system from over inflation. When
the system is not in operation, a distributor valve keeps
the boots held down by vacuum supplied through the
ejector system.
CAUTION
Operation of the surface deice system
in ambient temperatures below -40" C
can cause permanent damage to the
deice boots.
b.
Operation.
(1)
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 1/2
inch of ice to form on the boots before attempting ice
removal. Very thin ice may crack and cling to the boots
instead of shedding.
NOTE
Never cycle the system rapidly, this
may cause the ice to accumulate
outside the contour of the inflated
boots and prevent ice removal.
(2)
A two position deice switch on the
overhead control panel placarded SURFACE controls
the deicing operation. The switch is spring loaded to
return to the off position from SINGLE CYCLE AUTO or
MANUAL. When the SINGLE CYCLE AUTO position is
selected, the distributor valve opens to inflate the wing
boots. After an inflation period of approximately 6
seconds, an electronic timer switches the distributor to
deflate the wing boots and a 4 second inflation begins in
the horizontal stabilizer, stabilon and tailet 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
indicated
on
the
gage,
placarded
PNEUMATIC
PRESSURE, located in the center subpanel.
2-53. ANTENNA DEICE/ANTI-ICE SYSTEM.
a.
Description. The antenna deice/anti-ice system
removes or prevents ice accumulation on the
2-46
