TruTrak ADI Pilot II - Manual (Page 11)

TruTrak Flight Systems ADI Pilot I & II Autopilot Installation Manual
December 2009 9 8300-012 Rev B
speed is sufficient, the display will switch to the digital DG and show the current gyroscopically smoothened ground track. If
this does not occur, it is best to diagnose and fix the problem prior to first flight of the autopilot.
The activity adjustment (setup screen 1) determines how briskly the autopilot responds to roll disturbances. The setting can be
adjusted, in flight, over a wide range; thus the autopilot can be tailored to adapt to any aircraft installation.
The activity adjustment covers a numeric range of 0 to 24. Unless the value for a particular aircraft is provided by TruTrak, it is
advisable to start with a setting of zero and work up from there. Most installations would ultimately require somewhat higher
settings.
On the first flight, manually fly the aircraft to a suitable area for testing. Engage the roll and pitch axis by pressing and
releasing the lower right knob followed by the lower left knob. Observe that the display now shows the captured GPS ground
track as the selected direction of flight. The “AP” light and the “ALT” lights should both light up.
Press and hold the lower right knob for approximately 4 seconds until the first setup screen is shown on the display. The digit
“1” will be flashing, followed by the lateral activity value that was set earlier during pre-flight setup. Use the knob to select the
value zero (0), and observe the resulting control movement. Using the knob, increase the value one setting at a time, taking
time to observe an increasing level of control response. At some point, if too high a setting is chosen, the autopilot will be
jittery and over-active. Back the setting down using the knob until the autopilot is responsive but not over-active. It is best if
these adjustments are made in conditions of light to moderate turbulence (the TruTrak loves turbulence) so as to make it easy
to observe the response of the autopilot to disturbances. It will be noted that a fairly limited range of activity setting will be
acceptable; too low a value will result in sluggish response, while too high a value will result in nervous, inappropriate
response. Within this acceptable range there is room for individual preference; some people prefer a more aggressive autopilot
than others. It should be noted that any builder can accomplish this adjustment procedure and no professional is required.
Once the desired lateral activity level is established, press and release the lower right knob to store the value and move to the
second setup screen.
In the second setup screen, the digit “2” will be flashing, followed by the lateral torque value that was set earlier during pre-
flight setup. Again, it is best that this be done in light to moderate turbulence. The reason is that more torque is required of the
autopilot in turbulence than is the case in still air, because the velocity of the servo is greater as turbulence requires more rapid
servo movement. This means that the higher the activity setting, the higher the required torque setting.
The reason for setting the torque to a setting less than its maximum (12) is to reduce the current draw of the servo and to make
it easier to override the autopilot should the need arise. Manual override is not normally required, as using the control-wheel
switch or the knob will disengage the autopilot, but it is best to have a setting of torque which can be comfortably overridden if
necessary. Starting with the maximum torque setting (12), gradually decrease the value using the knob, until it is observed that
the autopilot no longer has the necessary torque to respond to disturbances; then increase the setting somewhat from that level
using the knob until no more slippage of the servo is observed. The clearest evidence of servo slippage is that the autopilot is
no longer able to roll the aircraft back to a level attitude after a roll disturbance occurs. Once the desired torque level is
established, press and release the lower right knob to store the value. Press and release the lower right knob two more times to
skip over setup screens 3 and 4.
Now the digit “5” will be flashing, followed by the vertical activity value that was set earlier during pre-flight setup. Use the
lower right knob to select the value zero (0), and observe the resulting control movement. Using the knob, increase the value
one setting at a time, taking time to observe an increasing level of control response. At some point, if too high a setting is
chosen, the autopilot will be jittery and over-active. Back the setting down using the knob until the autopilot is responsive but
not over-active. It is best if these adjustments are made in conditions of light to moderate turbulence (the TruTrak loves
turbulence) so as to make it easy to observe the response of the autopilot to disturbances. It will be noted that a fairly limited
range of activity setting will be acceptable; too low a value will result in sluggish response, while too high a value will result in
nervous, inappropriate response. Within this acceptable range there is room for individual preference; some people prefer a
more aggressive autopilot than others. It should be noted that any builder can accomplish this adjustment procedure and no
professional is required. Once the desired vertical activity level is established, press and release the lower right knob to store
the value and move to the sixth setup screen.
In the sixth setup screen, the digit “6” will be flashing, followed by the vertical torque value that was set earlier during pre-
flight setup. Again, it is best that this be done in light to moderate turbulence. The reason is that more torque is required of the
autopilot in turbulence than is the case in still air, because the velocity of the servo is greater as turbulence requires more rapid
servo movement. This means that the higher the activity setting, the higher the required torque setting.
The reason for setting the torque to a setting less than its maximum (12) is to reduce the current draw of the servo and to make
it easier to override the autopilot should the need arise. Manual override is not normally required, as using the control-wheel
switch or the knob will disengage the autopilot, but it is best to have a setting of torque which can be comfortably overridden if