King Air C90GTi, Руководство по подготовке пилотов

Страница: 213 / 557

flate the boots. A venturi ejector, operated
by bleed air, creates a vacuum to deflate the
boots and hold them down while not in use.
To assure operation of the system in the event
of failure of one engine, a check valve is in-
corporated in the bleed-air line from each en-
gine to prevent loss of pressure through the
c o m p r e s s o r o f t h e i n o p e r a t i v e e n g i n e .
Inflation and deflation phases are controlled
by a distributor valve.
A t h r e e - p o s i t i o n sw i t c h i n t h e I C E P RO -
T E C T I O N g r o u p o n t h e p i l o t ’s s u b p a n e l ,
placarded SURFACE DEICE–SINGLE–OFF
MANUAL, controls the deicing operation
(Figure 9-6). The switch is spring-loaded to
retur n to the OFF position from SINGLE or
MANUAL. When the SINGLE position is
selected, the distributor valve opens to in-
flate the boots. The wing boots will inflate
for approximately six seconds and then the
tail will inflate for approximately four sec-
onds. When both sets of boots have inflated
and deflated, the single cycle is complete.
When the switch is held in the MANUAL
position, all the boots will inflate simulta-
neously and remain inflated until the switch
is releas ed . Th e switch w ill retu r n to th e
OFF position when released. After the cycle,
the boots will remain in the vacuum hold-
down condition until again actuated by the
switch.
Electrical power to the boot system is re-
quired for the control valve to inflate the
boots in either single-cycle or manual op-
eration. With a loss of this power, the vac-
u u m w i l l h o l d t h e m t i g h t l y a g a i n s t t h e
leading edge.
A single circuit breaker on the copilot’s side
panel, receiving power from the center bus,
supplies the electrical operation of both boot
systems. Should the timer fail in the inflated
position, the surface deice circuit breaker
may be used as a manual control. Pull the cir-
cuit breaker out to deflate the boots, and push
in to inflate them. Treat the circuit breaker
as a manual control.
For most effective deicing operation, allow
at least 1/2 inch of ice to for m before at-
tempting ice removal. Very thin ice may crack
and cling to the boots instead of shedding.
Subsequent cyclings of the boots will then
have a tendency to build up a shell of ice out-
side the contour of the leading edge, thus
making ice removal efforts ineffective.
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
9-6
FOR TRAINING PURPOSES ONLY
9
PNEUMA
TICS
Figure 9-6. Surface Deice Controls