TM 55-1510-220-10
(6)
Altitude hold mode. Pressing the ALT switch
(autopilot mode selector control panel, fig. 3-20) when
desired altitude has been reached (with autopilot engaged)
will (1) cause the autopilot to fly the aircraft to maintain the
pressure altitude at which the aircraft was flying when ALT
switch was pressed, (2) illuminate the ALT annunciator light
(autopilot/flight director annunciator panel, fig. 3-22).
(7)
Indicated airspeed hold mode. Pressing the
IAS switch (autopilot mode selector control panel, fig. 3-22)
when desired airspeed has been reached (with autopilot
engaged) will (1) cause the autopilot to fly the aircraft to
maintain the indicated airspeed at which the aircraft was
flying when IAS switch was pressed, (2) illuminate the IAS
annunciator light (autopilot/flight director annunciator panel,
fig. 3-22).
i.
Autopilot Operation
(1)
Engaging autopilot:
1.
Autopilot engage switch (autopilot
mode selector control panel, fig. 320)
ENG.
NOTE
When the autopilot is engaged, the
yaw damper is also automatically
engaged.
The autopilot and flight director are coupled when both
units are engaged. When coupled, the autopilot accepts
guidance commands from the flight director. When the flight
director is not engaged, the autopilot accepts pitch and roll
commands from the pitch-turn control knobs as selected by
the pilot.
The autopilot may be engaged in any reasonable attitude
and in either the coupled or uncoupled mode. The autopilot
will smoothly acquire the command attitude. When
uncoupled, the autopilot will maintain the bank and pitch
attitude at the time of engagement.
(2)
Disengaging the autopilot. The autopilot may
be disengaged by the following:
(a)
Actuating compass INCREASE-
DECREASE switch.
(b)
Pressing TEST button on autopilot
mode selector control panel.
(c)
Pressing GO AROUND switch on left
power lever.
(d)
Pressing control wheel DISC switch to
APYD position.
(e)
The following functions will cause the
autopilot to automatically disengage:
1. Vertical gyro failure.
2. Directional gyro failure.
3. Autopilot power or circuit
failure.
4. Autopilot servo torque-
limiting circuit failure.
5. Autopilot trim failure.
(3)
Maneuvering.
(a)
To change flight functions, press the
desired mode button on the autopilot mode selector control
panel (fig. 3-20). The button will illuminate along its edges
and the autopilot annunciator lights on the instrument panel
will illuminate, indicating the respective modes in operation.
(b)
In
any
function
except
"after
h
glideslope capture", use the autopilot pitch control for
climbing or descending. Movement of the pitch control
establishes a pitch rate that is proportional to knob
displacement. If any vertical mode button has been selected,
it will automatically release when the pitch control knob is
rotated.
(c)
When HDG mode is selected, the
autopilot will command the aircraft to execute it turn, then
maintain the heading set by t111( heading marker.
(d)
Use the autopilot turn control to
command a roll rate when the autopilot is engaged. At the
time control is returned to detent, the autopilot maintains the
bank angle (up to approximately 30 degrees). Rotating the
turn control when the autopilot is engaged and a lateral mode
is selected (except APPR and GA modes) will cause the
selected lateral modes to release.
(4)
Control wheel synchronization. The PITCH
SYNC & CWS button on the pilot's control wheel (fig. 2-17)
can be used instead of the pitch/ turn control to establish the
aircraft in a desired attitude. Depressing this button causes
autopilot servos to disengage from the control surfaces. The
pilot then flies the aircraft manually to a desired
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