(8) Vertical speed hold mode button-indicator. Depressing the vertical speed hold mode button-indica-
tor, placarded VS , will command the system to maintain the current vertical speed or to allow a new vertical speed
to be selected with either the autopilot pitch wheel or by using the touch control steering switch on the control
wheel. When operating in the VS mode the ON indicator located on the face of the switch will be illuminated and
the target vertical speed will be displayed on the PFD VSI box.
(9) Altitude preselect mode button-indicator. Depressing the altitude preselect mode button-indicator,
placarded ALT SEL , will command the light control computer to arm and capture and maintain the altitude dis-
played on the altitude preselector (Fig. 3-9). When operating in the ALT SEL mode the ARM or CAP indicators
located on the switch face will be illuminated as appropriate.
(10) Altitude hold mode button-indicator. Depressing the altitude hold mode button-indicator, placarded
ALT , commands the light control computer to hold the current altitude, and will illuminate the ON indicator located
on the face of the switch. Capturing the altitude displayed on the altitude preselector will also cause the system to
maintain that altitude.
i. Control-Wheel Mounted Autopilot Disconnect Switches. A bi-level autopilot/electric trim/yaw damper dis-
connect switch, placarded DISC -AP & YD - TRIM , is mounted on each control wheel (Fig. 2-29). Depressing the
switch to the irst level will disconnect the autopilot and the yaw damper. Depressing the switch to the second level
will also disconnect the electric elevator trim.
j. Touch Control Steering (TCS). A control-wheel mounted touch control steering switch (Fig. 2-29), placarded
TCS , allows the pilot to manually change aircraft attitude, altitude, vertical speed, or airspeed without disengaging
the autopilot. The TCS switch is held depressed while the aircraft is maneuvered to the new attitude, altitude, vertical
speed, or airspeed. When the switch is released, the autopilot will automatically synchronize to the vertical mode. If
an air data mode (IAS or VS) has been selected, the selected value will be synchronized to the current value when
the switch is released.
k. Go-Around Switch. A pushbutton switch located on the left power lever (Fig. 2-19), placarded GO AROUND
, activates the light control system go-around mode when depressed. Go-around mode will disengage the autopilot,
command a wings-level 7-degree nose-up attitude, and engage the yaw damper.
l. Rudder Boost/Yaw Control Test Switch. A three-position toggle switch located on the pedestal extension
(Fig. 2-19), placarded RUDDER OFF - YAW CONTROL TEST , arms the rudder boost system and is used to test
for correct operation of the stability augmentation computer.
m. Autopilot LEFT or Autopilot RIGHT Select Switch. A pushbutton button-indicator located on the pedestal
extension, placarded A/P LEFT or A/P RIGHT , selects which side s FMS computer will provide inputs to the light
n. PFD symbology and Operating modes. Refer to the vendor s operator manual and the AIRPLANE FLIGHT
MANUAL SUPPLEMENT for description and operating instructions regarding the EFI-890R display.
o. 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 deined as:
No lateral light director mode selected
Bank angle less than 6 degrees
If the above conditions are satisied, 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 PFD, as it is the default lateral mode when no other lateral steering mode is
selected. Autopilot engagement is annunciated on the PFD.
Roll hold mode. The autopilot will recognize the roll hold mode as being operational when:
No lateral light director mode has been selected
The aircraft s bank angle is greater than 6 degrees, but less than 35 degrees
The autopilot is engaged