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Abnormal Procedures
TC FAIL
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 blind-mounted turn
coordinator has failed
, a yellow “
TC FAIL
” message is displayed
on the PFD. In addition, the autopilot, if it were engaged at the
time, will automatically kick off and the AP disconnect aural tones
will be heard.
Functionality Lost:
If on the ground, the autopilot will not allow engagement in any
mode with this condition.
If the turn coordinator fails at any time after initially working during
any given ground operation or flight, then the only autopilot
functionality that has been lost is the automatic, behind-the-
scenes comparator that is running between the AHRS and the
blind-mounted turn coordinator The autopilot will automatically
disengage but will allow manual re-engagement and will still
function in all modes during this condition.
Recommended Pilot Action:
If on the ground during this condition, cycle power to the turn
coordinator by cycling the avionics master. This also has the
affect of cycling power to the autopilot itself which would clear any
false reports of TC failure.
If the alert is presented at some time after initial autopilot
engagement, consider re-engaging the autopilot and continue
standard autopilot operations but be vigilant knowing that the
AHRS-TC comparator is not running.
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