A steady illumination of UP TRIM or DN TRIM
annunciator indicates that the automatic
synchronization is not functioning and the
autopilot should not be engaged.
b. Turn knob Center.
c. ELEV TRIM switch On.
d. Control wheel Hold to mid travel.
e. AP button Press. AP ENGAGE and YD
ENGAGE annunciators on autopilot controller
will flash. Servo clutches will engage. FD
flag on ADI should be in view.
f. Control movement Check.
(1) Rudder pedals Overpower slowly. YD
ENGAGE annunciator stops flashing.
(2) Control wheel Overpower slowly in both
pitch and roll axis. AP ENGAGE
annunciator stops flashing. FD flag on
If autopilot or yaw damper disengages
during overpower test or if AP ENGAGE or YD
ENGAGE annunciator continues to flash, the
system is considered non-operative and
should not be used. The elevator trim
system must not be forced beyond the limits
that are indicated on the elevator trim tab
g. Elevator trim follow-up Check.