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5-6
Abnormal Procedures
LOSS OF TURN COORDINATOR
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:
A failure of the aircraft turn coordinator is indicated by an alert
message (“TC FAIL”) displayed in the autopilot mode annunciator
area of the PFD displays. The autopilot will not disconnect under
these conditions if experienced in-flight.
Functionality Lost:
One of the two attitude comparators (see Comparators segment
in Section 1 of this manual) that is running in the background will
be inoperative in this case.
If the turn coordinator is failed upon initial power-up, the autopilot
will be prevented from engaging in any mode. This special case
is indicated by a yellow “
AUTOPILOT INOP TURN
COORDINATOR FAIL
” message in the center of the PFD
autopilot mode annunciator area.
Recommended Pilot Action:
Apply extra attention to the normal instrument cross check and if
the PFD display(s) are assessed to be accurate, manually re-
engage the autopilot in the desired mode.
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