BendixKing KFC 500 - Manual (Page 20)

Normal Operation
30 June 15, 1999 006-08769-0000
Normal Operation
31 006-08769-0000 June 15, 1999
Altitude Hold (ALT)
The light above the ALT push-button
illuminates and “ALT” is displayed on
the EADI in green when the Altitude
Hold mode is activated by depress-
ing the ALT push-button on the
mode select panel or by automati-
cally sequencing through Altitude
Arm and Altitude Capture via the
KAV 485. In the Altitude Hold mode,
the flight director commands pitch
attitudes for tracking of the helicopter
altitude at the moment of mode
selection. The system normally uses
barometrically corrected altitude, but
can use pressure altitude in the
event barometric altitude is not avail-
able. Altitude Hold mode also
requires valid vertical acceleration
from the KRG 333. Altitude Hold can
be entered directly or in conjunction
with the Altitude Select mode.
Engaging Altitude Hold directly dur-
ing a climb or descent will cause the
aircraft to fly through the desired alti-
tude and then return to the desired
altitude from the other side. For this
reason, the vertical speed should be
limited to 500 fpm when this method
of Altitude Hold engagement is used.
Selecting Altitude Hold after the
Altitude Select mode has been
engaged does not cancel Altitude
Arm indication (white “ALT” on
EADI). The flight director will com-
mand the aircraft to hold the altitude
present at the moment of mode
selection.
The commanded altitude hold refer-
ence value is displayed on the EADI.
This value may be modified by mov-
ing the CBT switch forward
(decrease reference altitude) or rear-
ward (increase reference altitude).
The pilot may also press the FTR
switch and manually fly the aircraft to
a new altitude. The AFCS will hold
the new altitude reference existing at
the time of release of the FTR
switch.
Continuous flashing of the annunci-
ator lamp above the push-button and
the flashing of and changing color
from green to yellow of the ALT
annunciation on the EADI indicates
loss of a valid altitude signal from the
air data computer or loss of valid ver-
tical acceleration. The flashing con-
tinues until the pilot pushes and
releases the ALT push-button on the
mode select panel (acknowledges
loss of the mode) or selects another
pitch mode. The ALT push-button on
the mode select panel may be used
to cancel the Altitude Hold mode at
any time. Upon manual deactivation,
the annunciator lamp above the ALT
push-button and the green ALT
annunciation on the EADI will flash
for five seconds. This flash
sequence will terminate upon reacti-
vation of ALT or another pitch mode.
receiver, invalid selected course from
EHSI). The flashing annunciation
may be extinguished by pressing and
releasing the APR push-button (pilot
acknowledgment) on the mode
select panel. If glideslope invalid
occurs for approximately 30 seconds
during glideslope arm the system will
revert back to the previously
engaged pitch mode. If glideslope
invalid occurs for approximately 5
seconds during the capture or track
phase the system will revert to pitch
attitude hold.
Autolevel Mode
The KFC 500 incorporates a sub-
mode called autolevel anytime the
autopilot/flight director system is APR
coupled on an ILS and the Radar
Altimeter is valid. At approximately
100 feet AGL the system will initiate
autolevel. The autopilot will discon-
tinue GS (glideslope) track and auto-
matically intercept and track approxi-
mately 50 feet AGL from the radar
altimeter. The system will hold this
radar altitude until disconnected.
Note: The Autolevel Mode is
approved for VFR operation only.
If the runway is not in sight at the
decision height use of the
Autolevel Mode is not approved.
KAV 485 Altitude Select
Altitude Select (ALT SEL)
The Altitude Select mode provides a
method for selecting, capturing, and
tracking another altitude. Altitude
Select will automatically Arm after a
change in the altitude select value.
“ALT” is annunciated in white on the
EADI when the Altitude Select mode
is armed. The selected altitude is dis-
played in the KAV 485’s selected alti-
tude window. ALT SEL requires use
of PIT, VS, or IAS modes to be used
to transition to the selected altitude.
Upon reaching the altitude capture
point, the selected vertical mode will
cancel, the flight director will engage
Altitude Capture and then Altitude
Hold. Altitude Select must be deacti-
vated to inhibit capture and tracking
of the pre-selected altitude. If the
value of selected altitude is changed
while in altitude capture, the system
reverts to pitch attitude hold mode. In
the event of sustained invalid alti-
tude, ALT SEL mode will deactivate.
To disengage Altitude Select, press
the SEL mode push-button on the
KAV 485. Detailed operation of the
KAV 485 is provided at the end of
this section.
ALT
☛
0
2
3
4
5
6
7
8
9
ALT
1,160
30.08 1,700
1
ı
ALT
ALERT
ALT
SEL
SEL
U P LL
V S
Selected
Altitude
Display