TM 1-1510-224-10
15. RUDDER
BOOST/YAW
CONTROL
TEST switch -
RUDDER
BOOST.
Check RUDDER BOOST annunciator
extinguished.
16. Electric elevator trim - Check.
a.
ELEV TRIM switch - On.
b.
Pilot and copilot trim switches -
Check operation.
WARNING
Operation of the electric trim system should
occur
only
by
movement
of
pairs
of
switches. Any movement of the elevator trim
wheel while depressing only one switch
element indicates a trim system malfunction.
The electric elevator trim control switch must
then be turned OFF and flight conducted by
operating the elevator trim wheel manually.
Do not use autopilot.
c.
Pilot and copilot trim switches -
Check individual element for no
movement of trim, then check
proper operation of both elements.
d.
Pilot trim switches - Check that pilot
switches override copilot switches
while
trimming
in
opposite
directions,
and
trim
moves
in
direction commanded by pilot.
e.
Pilot or copilot trim switches - Check
trim disconnects while activating
pilot or copilot trim disconnect
switches.
f.
ELEV TRIM switch - OFF then on
(ELEC
TRIM
OFF
annunciator
extinguishes).
p.
Digital Flight Control System Modes of
Operation.
(1) Heading hold mode (wings level). The
basic lateral mode of the autopilot is heading hold.
Heading hold mode is defined as:
Autopilot engaged
No lateral flight director mode selected
Bank angle less than 6 degrees
If the above conditions are satisfied, the
autopilot will roll the aircraft to a wings level attitude.
When the aircraft's bank angle is less than 3 degrees for
10 seconds, the heading hold mode is automatically
engaged. The heading hold mode is not annunciated on
the EADI as it is the default lateral mode when no other
lateral steering mode is selected. Autopilot engagement
is annunciated on the EADI.
(2) Roll hold mode. The autopilot will
recognize the roll hold mode as being operational when:
No lateral flight director mode has been selected
The aircraft's bank angle is greater than 6
degrees, but less than 35 degrees '
The autopilot is engaged
When the above conditions have been satisfied,
the autopilot will maintain the desired bank angle. With
the autopilot engaged, bank angles up to 35 degrees
can be established using the turn knob. If touch control
steering (TCS) was used to initiate the roll, bank angles
up to 35 degrees can be maintained and TCS ENG will
be annunciated on the EADI.
(3) Heading select mode. The heading
select mode is used to intercept and maintain a
magnetic heading. The mode is selected with the HDG
switch-indicator on the flight director mode selector
panel (fig. 3-22). Heading mode selection is
annunciated by a green HDG annunciator on the EADI.
The heading marker is set on the heading dial of the
EHSI by means of the instrument remote controller
(pedestal extension, fig. 2-14). When operating in the
heading mode the flight control computer provides inputs
to the pitch and roll command cue on the EADI to
command a turn to the heading selected by the heading
marker located on the EHSI. Heading mode signal gain
is a function of airspeed. Bank angle limit is 25 degrees
in the heading select mode.
Heading select mode is cancelled by:
Capture of any other lateral steering mode
Selecting go-around mode
Selecting standby mode
EFIS 1/2 reversionary selection
NAV, ATT, or HDG reversionary selections
(4) VOR (NAV) mode. The VOR mode
provides for automatic intercept, capture, and tracking of
a selected VOR radial, using the selected navigation
source displayed on the EHSI. The navigation source
displayed on the EHSI is a function of the VOR/localizer
(V/L) pushbutton selector switch located on the display
controller (fig. 3-8). Prior to engaging the VOR (NAV )
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