Beechcraft C-12C Operator And Technical Reference Manual page 319

(8) Altitude Preselect Mode (ALTSEL). The
altitude preselect mode is selected by pressing the
ALTSEL button on the mode selector. The desired
altitude is selected on the altitude preselect controller.
Pitch hold, VS or IAS may be selected as a mode to fly
to the selected altitude.
bracket trip point, the ALTSEL ARM annunciator,
along with the selected pitch mode, are illuminated on
the mode selector.
altitude, the system automatically switches to the
ALTSEL CAP mode and the previously selected pitch
mode is cancelled. When the altitude is reached, the
ALTSEL CAP mode is automatically cancelled and the
flight director switches to the ALT hold mode. If the air
data computer is not valid, the altitude preselect mode
cannot be selected. The ADI command cue will bias
out of view if the VG is not valid.
(9) Altitude Hold Mode (ALT). The altitude-
hold mode is selected by pressing the ALT button on
the mode selector. When ALT mode is selected, it
overrides the APR CAP, GA, IAS, VS, and ALTSEL
CAP modes. In the ALT mode the pitch command is
proportional to the altitude error provided by the air
data computer. The altitude error signal is gain
programmed as a function of airspeed. Pressing and
holding the TCS button allows the pilot to maneuver
the aircraft to a new altitude hold reference without
disengaging the mode. Once engaged in the altitude
hold mode, the mode will be reset if the air data
MODE
Yaw Damper
Basic A/P
Heading Select
VOR
When outside the altitude
When reaching the bracket
Table 3B-3. Autopilot System Limits (Continued)
CONTROL OF SENSOR
Yaw Control
Touch Control
Steering TCS
Turn Knob
Pitch Wheel
Heading Hold
HSI Heading
Select Knob
Course Knob, NAV
Receiver and
DME Receiver
computer is not valid and the ADI command cue will
bias out of view if the VG is not valid.
If the baro setting on the altimeter is
changed, a command is generated to fly
the aircraft back to the original altitude
reference.
(10) Go-Around Mode. The go-around mode
is selected by pressing the remote go-around switch.
When selected, all other modes are reset, and the
remote Go-Around (GA) and Yaw Damp (YD ENG)
annunciators will be illuminated. The ADI command
cue receives a wings level command (zero command
when roll is zero). The command cue also receives
the go-around command, which is a 7° visual pitch up
attitude command.
autopilot, but the yaw damper remains on.
Once go-around is selected, any roll mode can
be selected. The wings level roll command will cancel.
The go-around mode is cancelled by selecting another
pitch mode, or TCS.
f. Autopilot
controller engages the autopilot and yaw damper, as
well as manually controlling the autopilot through the
turn knob and pitch wheel. The autopilot system limits
are listed in Table 3B-3.
PARAMETER
Engage Limit
Roll Control Limit
Pitch Control Limit
Roll Angle Limit
Roll Rate Limit
Pitch Angle Limit
Roll Angle Limit
Roll Angle Limit
Roll Rate Limit
CAPTURE
Beam Angle Intercept
(HDG SEL)
Roll Angle Limit
Course Cut Limit at
Capture
TM 1-1510-218-10
NOTE
Selecting GA disconnects the
Controller. The
VALUE
Unlimited
Up to ± 45° Roll
Up to ± 20° Pitch
± 30°
± 15°/sec
± 15° Pitch
Less than 6° and no roll
mode selected
± 25°
± 3.5°/sec
Up to ± 90°
± 25°
± 45° Course
autopilot
3B-29