TM 1-1510-262-10
b. Operation.
To ensure adequate bleed air pressure to the deice boots, do not simultaneously actuate surface
and antenna deice systems in the manual mode.
(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.
Never cycle the system rapidly, this may cause the ice to accumulate outside the contour of the
inlated 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 inlate the wing boots. After
an inlation period of approximately 6 seconds, an electronic timer switches the distributor to delate the wing boots
and 4-second inlation begins in the horizontal stabilizer, stabilons and taillet boots. When these boots have inlated
and delated, the cycle is complete.
(3) If the switch is held in the MANUAL position, the boots will inlate simultaneously and remain inlated
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 actuated by the switch.
(4) Either engine is capable of providing suficient bleed air for all requirements of the surface deice
system. Check valves in the bleed air and vacuum lines prevent backlow through the system during single engine
operation. Regulated pressure is indicated on the gauge, placarded PNEUMATIC PRESSURE , and located on the
center subpanel.
2-56. ANTENNA DEICE/ANTI-ICE SYSTEM.
a. Description. The antenna deice/anti-ice system removes or prevents ice accumulation on the mission an-
tennas. Pressure regulated bleed air from both engines supply pressure to inlate or heat 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. Distributor valves control
inlation and delation phases.
To ensure adequate bleed air pressure to the deice boots, do not simultaneously actuate surface
and antenna deice systems in the manual mode.
Never cycle the system rapidly, this may cause the ice to accumulate outside the contour of the
inlated boots and prevent ice removal.
NOTE
Under conditions where one bleed air source is inoperative, suficient bleed air pressure for deice
inlation may not be available. Prior to deice boot inlation, check the regulated air pressure gauge
for a minimum of 16 PSI. If insuficient pressure exists, increasing engine N 1 and/or decreasing
altitude will increase bleed air pressure.
b. Antenna Deice System Switch. The antenna deice system is controlled by a switch placarded ANTENNA
SINGLE CYCLE AUTO - MANUAL 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
2-55
