BendixKing KFC 500 - Manual (Page 11)

Normal Operation Normal Operation
12 13 June 15, 1999 006-18081-0000 006-18081-0000 March 27, 1998
is stabilizing the helicopter against
outside disturbances and thereby is
augmenting the pilot effort. The
SCAS mode is designed so that heli-
copter attitude changes caused by
pilot control inputs are not signifi-
cantly counteracted by the stability
augmentation system. Only heli-
copter motions caused by outside
disturbances are counteracted.
Some amount of SCAS counterac-
tion is designed into the system for
better pilot feel in the Bell 430.
AP Mode
The autopilot (AP) push-button
engages the pitch, roll, and yaw axes
of the selected system and provides
trim follow-up for those axes.
Momentarily pressing the AP button
on the Mode Select Panel will acti-
vate this mode. The mode lamp
above the switch on the MSP and
the remote repeater AP ON annunci-
ator will illuminate to verify that the
selected flight computer has recog-
nized the button push. The Force
Trim system power for selected sys-
tem must be on and Force Trim sys-
tem not overpowered (detent
switches not activated on primary
system) for this mode to engage.
Autopilot mode will provide com-
mands to maintain the current pitch
attitude and heading. If the roll atti-
tude is not level upon AP engage-
ment, the autopilot will command a
back to the attitude existing at the
time that the pilot intervened.
Alternatively, attitude hold com-
mands may be modified by moving
the Cyclic mounted Beep Trim (CBT)
switch in the appropriate direction.
The yaw axis augments rotorcraft
stability by opposing uncommanded
yaw motion and providing ball cen-
tering. The yaw axis also provides
turn coordination and yaw trim (using
lateral acceleration). Lateral acceler-
ation is used by the system to pro-
vide the described functionality any-
time that the acceleration sensor is
valid. Loss of #1 hydraulic system
automatically disconnects the flight
control system from the yaw axis. In
case of #1 hydraulic power loss, con-
sult the Bell 430 Rotorcraft Flight
Manual for the procedures specified
for AFCS yaw axis operation.
Lateral Command Control
Activated by the Cyclic Beep Trim
(CBT) switch when the AP mode is
on, Lateral Command Control modi-
fies the autopilot’s reference roll atti-
tude. When Lateral Command
Control is used, the aircraft will be
commanded to follow the pilot’s or
copilot’s input to roll left or roll right. If
within 6° of level flight when the
switch is given a momentary push
the first click will yield 6° of bank in
respective direction. If greater than
6° of bank in either direction a
momentary push will result in 1° per
click. If the switch is pressed continu-
ously the system will command a
constant roll rate until the beep trim
switch is released. Upon release of
the CBT switch, the autopilot will
command the aircraft to maintain the
existing roll attitude. Roll attitudes of
less than six degrees of bank will
cause the autopilot to revert to com-
mands for roll-level with heading
hold. The AFCS is designed with
absolute attitude limits and rate lim-
its. During fly through or other
modes of operation , the aircraft atti-
tude/rate must be less than + or -
45°/15° per second in roll and + or -
15°/10° per second in pitch and 15°
per second in yaw for the AP mode
to remain engaged. If these limits
are exceeded the autopilot will auto-
matically disconnect. level attitude and maintain the head-
ing at the time the aircraft rolls level.
Desired roll and pitch attitudes may
be selected by several methods.
With the autopilot engaged the pilot
can manually adjust the attitude of
the helicopter by pressing and hold-
ing depressed the Force Trim
Release (FTR) switch on the cyclic
while repositioning the helicopter to
the desired attitude. Upon release of
the FTR, the autopilot will provide
commands to maintain the target
pitch and roll attitude if greater than
6°. If the roll attitude is less than 6°
the system will return to roll level atti-
tude and hold the existing heading.
While the Autopilot is engaged the
pilot may press the FTR switch,
manually move the controls to fly the
aircraft to a new attitude and release
the FTR switch and cyclic. The sys-
tem will then hold this new attitude in
pitch and roll if greater than 6
degrees. If less than 6 degrees
bank angle the system will roll wings
level and assume the new heading.
On the primary system the pilot may
momentarily fly the aircraft manually
at any time (via the Fly Through
mode with detent switch activation).
When detents are activated the sys-
tem will temporarily revert to SCAS.
After release of the cyclic (over-
power force is removed and detent
switches not activated) the autopilot
will return to attitude hold (AP
annunciated), and fly the aircraft
AFCS DISC
CYCLIC GRIP SWITCHES
CBT
FTR
AP
AP ON