The autopilot and yaw damper have a contin-
uous monitor that, in the event of a malfunc-
tion, causes a system disconnect in the AP, YD,
RB or in all three. In the event of a monitor dis-
connect, the “AP” caption turns red, flashes for
5 seconds, then goes steady. The disconnect
aural alert (cavalry charge) sounds, and will
continue to sound until acknowledged by ei-
ther pilot depressing the MSW (Figure 16-
47) for at least 2 seconds (until the “WHEEL
MSTR” message is displayed on CAS).
An AP self-monitored disconnect is not always
accompanied by a YD or RB system fail-
ure/disconnect. The yaw damper may not dis-
connect with an autopilot monitor disconnect,
but after a crewmember depresses the MSW
to silence the AP disconnect aural alert, the
yaw damper will disengage also. In this case,
the amber “YD” will flash for 5 seconds and
then disappear if the malfunction was not in
the yaw damper. If the AP monitor discon-
nect was due to a YD malfunction, the amber
“YD” turns steady and remains displayed.
After either crewmember depresses the MSW
following an AP monitor disconnect, the red
“AP” may extinguish if the malfunction is
cleared, or it will turn to a steady amber “AP”
if the problem still exists and, in this case the
autopilot will not reengage.
A steady amber “AP,” “YD,” or “RB” will not
allow the autopilot to be reengaged. With only
a steady amber “AP” displayed, the yaw
damper and the rudder boost should still be op-
erational. If a steady “YD” is displayed, nei-
ther the yaw damper or rudder boost are
operational.
The crew may be able to clear a steady amber
“AP,” “YD,” or “RB” by cycling the IC/SG 2
circuit breaker on the copilot’s CB panel.
Mistrim Annunciation
When the autopilot is engaged and the roll or
pitch servo remain energized for a longer than
normal period (mistrim), the condition will be
annunciated with a CAS message.
A white “AP ELEV MISTRIM” message will
be displayed by the CAS when there is a
mistrim in the pitch axis (Table 16-5). If the
mistrim continues (more than 10 seconds),
or current drawn by the pitch servo is exces-
sive the message will turn amber and it will
be necessary for the crew to correct the
mistrim condition. Further servo loading will
result in a AP monitor disconnect.
The autopilot does not have a capability to trim
in the roll axis; therefore, if there is a mistrim
in the roll axis, an amber “AP AIL MISTRIM”
message will be displayed by the CAS and
there will be no white advisory message (Table
16-5). Further servo loading will result in a
AP monitor disconnect.
L E A R J E T 4 5
P I L O T T R A I N I N G M A N U A L
16-80
FOR TRAINING PURPOSES ONLY
FlightSafety
international
CAS Message
Logic Summary
W = Warning
C = Caution
A = Advisory
Type
Msg
C
AP AIL MISTRIM
C
A
AP ELEV MISTRIM
AP ELEV MISTRIM
Autopilot elevator servo holding torque
Autopilot elevator servo holding excessive torque
C
AP FAIL
Autopilot/yaw damper inoperative
Autopilot aileron servo torque excessive
Table 16-5. AUTOMATIC FLIGHT CONTROL SYSTEM CAS MESSAGES