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Abnormal Procedures
If the autopilot does not conduct a successful automatic restart,
consider attempting an autopilot restart by cycling the autopilot
circuit breaker.
AHRS-TC MISCOMPARE DURING GROUND OPERATIONS
In Cirrus SR2X or Piper PA46 installations where the DFC90 is
replacing a STec 55X autopilot, the DFC90 will use the previously
installed turn coordinator as a source of attitude comparison. In
all other cases, there is no connectivity to a turn coordinator and
this scenario does not apply.
Failure Indication:
If the DFC-PFD system recognizes that the AHRS and the Turn
Coordinator are experiencing a miscompare during ground
operations before a successful engagement, a yellow
“
AUTOPILOT INOP AHRS MISCOMPARE
” message is
displayed along middle of the PFD annunciator strip.
Functionality Lost:
This message can only occur after system power application and
if it does, the autopilot will not engage in any modes while this
alert is active. This warning is designed to cover the condition
where, after power up, the system is reading a difference
between a valid TC signal and a valid AHRS signal. In this case,
autopilot engagement is prevented.
Recommended Pilot Action:
Consider cycling power to the PFD and autopilot via the circuit
breakers or using the Avionics Master. If that was not successful,
plan your flight without autopilot.
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