BendixKing KFC 500 - Manual (Page 21)

Normal Operation Normal Operation
32 33 June 15, 1999 006-18081-0000 006-18081-0000 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.
tion 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.
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, GA or IAS modes to be
used to transition to the selected alti-
tude. Upon reaching the altitude cap-
ture point, the selected vertical mode
will cancel, the flight director will
engage Altitude Capture and then
Altitude Hold. Altitude Select must be
deactivated 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 altitude, 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.
KAV 485 Altitude Select
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