TruTrak Digiflight Install Manual - Manual (Page 12)

DigiFlight Autopilot Installation Manual TruTrak Flight Systems
March 2002 Printing 10
The next step in the check-out procedure is to verify that the servos run, and in the correct direction. At this point, the display
differs depending on autopilot model.
DigiFlight 200 DigiFlight 200 VS
The screen will show that
the altitude portion of the
autopilot is still disengaged.
Press ENTER to engage the
altitude hold function.
MAG 005
SEL 005 AP ON
$
MAG 005 ALT HOLD
SEL 005 AP ON
The lower-right of the
screen will show the present
value of selected vertical
speed, (SVS) which will be
approximately zero. Press
ENTER to move the cursor
to the SVS field, then use
the knob to set the value to
0. The display will change to
show altitude hold mode.
MAG 005
SEL 005 SVS 100
$
MAG 005 ALT HOLD
SEL 005 SVS 0
In both cases, the selected heading will be underlined on the bottom left of the display, and the autopilot will be in the altitude
hold mode. Both the pitch and roll servos should stop, or move only very slowly.
DigiFlight 200 DigiFlight 200 VS
The autopilot programmer unit needs to be out of the panel, so
that it can be gently tipped fore-and aft to simulate nose-up
and nose-down flight. If the autopilot is tipped in a nose-down
maneuver, the control should move in such a way as to
attempt to move the control yoke or stick back, in an effort to
raise the nose of the aircraft. Similarly, a nose-up tipping of
the autopilot should push the yoke or stick forward in an
effort to lower the nose of the aircraft.
Using ENTER will toggle the altitude hold on and off. When
the altitude hold is off, the pitch servo is electrically
disconnected and will not move in response to disturbances.
With the cursor in the SVS field, rotate the knob clockwise
until several hundred feet per minute is showing in the field.
At this point, the pitch servo should be moving the control
yoke or stick back, in an effort to raise the nose of the aircraft.
Similarly, rotating the knob counter-clockwise to select a
negative vertical speed (descent) the pitch servo should be
moving the controls in such a way as to lower the nose of the
aircraft.
Using ENTER will toggle the cursor back and forth between
the SVS field and the SEL (selected heading) field. The
cursor will revert back to the selected heading field after a few
seconds of inactivity.
If the direction of movement of the pitch servo is incorrect, install or remove the jumper between pins 1 and 2 of the autopilot
connector and repeat the setup to verify correct results up to this point.
The roll servo should also be responding at this time, moving the controls in such a way as to turn the aircraft from the current
heading (shown as a 3-digit number after the word MAG in the upper-left of the display) to the selected heading (shown as a 3-
digit number after the word SEL in the lower left of the display). The initial value of the selected heading is the current heading
of the aircraft at the moment of engagement, but the knob can be used to modify the selected heading. When the heading
shown as SEL agrees with the heading of the aircraft shown in the top line as MAG, the roll servo should stop or run only very
slowly. If the knob is rotated clockwise, to a selected heading right of the current heading, the control yoke or stick should
move in such a way as to roll the aircraft to the right. Conversely, a selected heading to the left of the current heading will
move the controls in the opposite direction to attempt a roll towards the left. If servo direction is not correct, the wires going to
pins 4 and 5 of the roll servo (pins 32 and 33 on the main connector) must be reversed to achieve the correct response. If a
servo does not move at all, double-check the LAT TORQUE or VRT TORQUE setting as appropriate. If a servo jitters but
does not actually rotate, check the wiring on the four servo drive lines to that servo for continuity and correctness. If the servo
does not seem to have any torque, check the relevant torque control line for continuity and correctness.
At this time, check that each servo arm or capstan is properly operating the controls. For servo installations using an arm, check
that as the controls go from limit to limit the arm of the servo remains in the operating range of the servo (a maximum of 100
degrees total rotation) and that when the controls are centered, the connecting pushrod is approximately perpendicular to the
arm of the servo. For capstan systems, insure that the cabling remains at proper tension and is properly secured as the servo
moves the controls from stop to stop. Insure that each servo remains secure in its mounting and does not flex its mounting
bracket as it drives the control to its stops. For installations using an arm, insure that as the servo moves the control towards the
end of control travel it does not cause the main control’s torque tube or push-pull tube to flex in any way that could cause