King Air C90GTi, Pilot Training Manual

Page: 231 / 557

ANTI-ICE CONTROLS
The ice vane and bypass doors are extended
or retracted simultaneously through a link-
age system connected to electric actuators.
T h e a c t u a t o r s a r e e n e r g i z e d t h r o u g h
switches in the ICE PROTECTION g roup
located on the pilot’s left subpanel (Figure
10-12). The ICE VANE switches extend the
s e p a r a t o r s i n t h e o n p o s i t i o n a n d r e t r a c t
them in the OFF position, which is used for
all nor mal flight operations.
The ice vanes should be extended whenever
there is visible moisture at +5ºC. When the
ice vanes are extended, the two g reen advi-
sor y annunciators will illuminate, and be-
c a u s e t h e a i r f l ow i n t o t h e e n g i n e w i l l b e
restricted, there will be a drop in torque and
a slight increase in ITT. When the ice vanes
and bypass doors are retracted, the annun-
ciators will extinguish, torque will be re-
stored, and ITT will decrease.
The anti-ice vanes are controlled by switches
located on the left subpanel. The LEFT and
RIGHT ENGINE ANTI-ICE switches have
positions labeled “ON” and “OFF,” while the
ACTUATORS switch has positions labeled
“STANDBY” and “MAIN.”
The actuators have dual motors to provide
a r e d u n d a n t s y s t e m . T h e AC T UATO R S
sw i t c h a l l ow s t h e s e l e c t i o n o f e i t h e r t h e
MAIN or STANDBY actuator motor. The
main and standby actuators have different
circuitry but share the same torque tube drive
system.
The vanes have only two positions; there
are no inter mediate positions. The system
is monitored by L and R ENG ANTI-ICE
(green) and L and R ENG ICE FAIL (yellow)
annunciators (Figure 10-13). Illumination
of the L and R ENG ANTI-ICE annunciators
indicate that the system is actuated.
Illumination of the L or R ENG ICE FAIL an-
nunciator indicates that the system did not
operate to the desired position. Immediate
illumination of the L or R ENG ICE FAIL an-
nunciator indicates loss of electrical power,
whereas delayed illumination indicates an
inoperative actuator.
The yellow ENG ICE FAIL annunciator cir-
cuit compares the ANTI-ICE switch posi-
tion to the microswitches checking ice vane
open or closed. After a 35-second delay, the
annunciator will illuminate if the switch po-
sition and microswitches do not ag ree. In
addition, if the power source for the actua-
tor system selected (MAIN or STANDBY)
is removed, the ICE VANE FAIL light will
illuminate immediately. In either event, the
STANDBY actuator should be selected.
KING AIR C90GTi/C90GTx PILOT TRAINING MANUAL
10-12
FOR TRAINING PURPOSES ONLY
10
ICE
AND
RAIN
PRO
TECTION
Figure 10-12. Anti-Ice Controls
Figure 10-13. Caution and Advisory
Annunciators