Ap Disconnect Switch Function To Reset A Failure; Autopilot/Yaw Damper Disconnects With No Event Codes Logged - Honeywell PRIMUS 1000 Pilot's Manual

R
PRIMUS 1000 Integrated Avionics System

AP Disconnect Switch Function to Reset a Failure

The AP disconnect switch, mounted on the control wheel, disconnects
the autopilot and resets monitor–induced autopilot disconnects. If the
autopilot disconnects because a monitor in the pitch, roll, or yaw axis
senses control pressure (for example, a pilot's feet on the rudder when
the yaw damper tries to execute a yaw damper function), the
message is displayed on the PFD. To reactivate the autopilot, push the
AP disconnect switch for 2 seconds to reset the monitors. The autopilot
can then be re–engaged.
Autopilot/Yaw Damper Disconnects with No Event
Codes Logged
If an unintentional autopilot and/or yaw damper disconnect occurs
without an event code stored in the IAC, the disconnect may be
attributed to a normal event. A normal event is one in which the autopilot
computer function in the IAC received a normal request to disconnect,
such as the following:
D
Control wheel AP disconnect switch – faulty switches, splices, or
wiring may cause this signal to open.
D
Pitch trim switch input – faulty trim switches, connectors, or wiring
may result in the IAC receiving a trim request that, by design,
disconnects the autopilot. Also, an inadvertent activation of the trim
switch results in an AP disconnect.
D
AP or YD engage buttons on the autopilot controller are
inadvertently being pushed or are intermittent in operation.
Other conditions that cause disconnect without a stored event code are:
D
Low power sensed by the IAC, due to faulty wiring or circuit breaker.
D
Poor grounds to the IAC.
D
Shorts to ground of the 28V clutch engage lines from the IAC to the
servos.
If crew reports of disconnects cannot be substantiated with an event
code, the items listed above need to be checked.
NOTE: AP/YD disconnects caused by the above situations do not
result in an AP FAIL message posted above the attitude
sphere on the PFD.
Troubleshooting
7-30
AP FAIL
A28–1146–134
REV 1 Jan/03