Avidyne DFC90 - Comparators

System Overview 1-15
COMPARATORS
The DFC90 autopilot is always running comparators in the
background. There are several types of comparators running
during operation of the autopilot as noted in the chart below. If
conflicting information is provided, the comparator identifying the
conflict with the accompanying pilot indication and autopilot
behavior is noted in the table below:
Type of
Comparator
Indication to Pilot
Autopilot behavior
Internal kinematic
comparator within
the AHRS
(compares AHRS
state data with
itself, eg. turn rate
without
accompanying
heading change,
etc)
“CROSSCHECK
ATTITUDE”
annunciation on
PFD for minor
issues and indicator
removal and
replacement by
“Red-X” for major
issues
No change for
“Crosscheck
Attitude” conditions
and potential
disconnect for Red-
X conditions
AHRS-to-Turn
Coordinator (TC)
Comparator [only
applicable for Cirrus
SR2x or Piper PA46
aircraft in which the
DFC90 is replacing
a STec 55X,]
Miscompare Alert
message(s)
presented to the
pilot on the PFD
(“AHRS
MISCOMP”) and in
the headset
(“GYRO
MISCOMPARE”)
Autopilot will not
disconnect if the
condition is
experienced in
flight. If the AHRS-
TC miscompare
condition was
present after initial
ground power-up,
the autopilot will be
prevented from
engaging in any
modes.
Change 3