TruTrak DFC Operating Manual - Manual (Page 10)

9
Additional Operating Instructions
Initializing the
Autopilot
The autopilot master switch
should be in the off position
when the engine is started.
Aircraft electrical systems can
generate voltage transients
during an engine start, and like
other avionics systems, the
autopilot should not be
subjected unnecessarily to these
conditions. After start up, turn
on the autopilot master switch
and
hold the aircraft
stationary as the internal gyros
are initialized. This takes
approximately ten seconds
during which time the display
will show the words
PWR UP
in
the lower right.
When initializing is
complete
PWR UP
will change
to
AP OFF
.
GPS Acquisition
Between the word MAG and
the three digit numeric display,
a flashing period
MAG•155
will
appear each time the GPS sends
a message to the autopilot (once
per second). This indicates the
GPS is working but has not yet
obtained a position fix. As long
as the period is shown, the
heading display cannot
transition to the
TRK
mode.
When the GPS does obtain a
fix, the period will be replaced
by an asterisk
MAG*155
. This
means that when a certain
velocity is attained
MAG
will be
replaced by
TRK
. This happens
at approximately 10 Knots
groundspeed as detected by
GPS and will even occur at
rapid taxi speeds.
Altitude Select With
AP Off
If a target or assigned
altitude is known prior to take-
off, this altitude can be set while
on the ground. As with the AP
on, pressing [ALT] twice will
display the
ALT SEL setup screen.
The procedure is to select the
desired altitude and then press
enter.
MAG 160 ALT 1350
PWR UP
The display will show the
selected altitude even though the
autopilot is still off. This will
serve as a reminder that the
autopilot will climb to the
selected altitude when engaged.
MAG 160 ALT 1350
AP OFF
Gyro Set
When the initializing has
been done correctly, the gyros
should already be centered at the
time of take off. If confirmation
of this is desired, with the
aircraft stationary on the
runway, pressing and holding the
encoder knob will put the gyros
in the fast centering mode. The
knob should be depressed for
approximately 10 seconds during