TruTrak EFIS AP (8300-057C) - Manual (Page 21)

TruTrak Flight Systems 19 EFIS Autopilot Installation Manual
in most aircraft will be left at zero (0). Micro activity is used only in aircraft in which a
return to the setup screen.
ake
ailable torque. This setting should be left at
en LOW, MED, or HIGH to suit a
vel
nd
be
t
ystem requires adjustment of the yaw damper parameters. With the autopilot
h a
and comfort. Once the ACTVTY has been set, click
MICRO setting
slow pitch rock has been observed in very still air. Sometimes there will be a small amount of lost motion
in an aircrafts control system, and the micro activity setting is a way to compensate for the lost motion.
Once the desired MICROACTIVITY has been selected, click the right knob to
The HALF-STEP setting in most cases will not need to be changed. If the half step setting is set to ON,
then the roll servo will now have higher resolution, and take smaller steps. While this setting will m
the servo take smaller steps, it will decrease the amount of av
OFF, unless it is observe that the wing moves up and down very slightly while in straight and level flight
in very still air. Click the right knob if the setting was not changed, to return to the setup screen.
STATIC LAG setting it is set to LOW at the factory but can vary betwe
particular static system. LOW value assumes a static system with very little “lag”; the HIGH value
assumes a fairly large amount of lag. To diagnose the lag of a particular system, it is necessary to be in
the altitude hold mode of the autopilot, prior to setting the STATIC LAG.
Once the autopilot is in altitude hold mode, re-enter the vertical setup mode. In still air, straight and le
flight, in altitude hold mode, observe whether the altitude appears to oscillate, or “hunt” slowly up a
down. If this is the case, it may be caused by several factors, one of which is the amount of lag in the
static system. Increasing the STATIC LAG value to MED or HIGH may cure the problem; however this
should be set to the smallest value that satisfactorily flies the aircraft in the pitch axis, as the larger the
value the less responsive the autopilot will be to vertical commands or altitude error. Other possible
causes of hunting in altitude hold are “lost motion” in the aircraft controls or too low a level of vertical
activity setting. Excessive lag in the static system itself can be caused by undersized static ports,
improperly placed ports, long static lines, or especially by attached equipment with large static reservoirs.
The autopilot can be adapted to cover a wide range of static systems, but in truly extreme cases it may
necessary to provide a separate static line for the autopilot so that other equipment attached to the por
does not degrade the autopilot’s performance. Click the right knob twice to return to the MAIN screen.
Yaw Damper First Flight
The Yaw Damper s
disengaged, level the aircraft and hand-fly the aircraft in still air. Press YD to engage the yaw damper.
Then enter the setup screen for the YD. Select CENTR, Centering is adjustable from -8 to 8 and has
enough authority to move the ball approximately one and one half times the width of the ball in either
direction. (Coarse adjustment was made using the potentiometer in the yaw damper module during the
earlier Initial Checkout Procedure.) Adjust the centering so that the ball is centered. Once the YD
LEVELING has been set, click to return to the setup screen. The next field, ACTVTY, determines how
aggressively the yaw damper responds to yaw disturbances. Yaw damper activity can range from 0 (off)
to 12 (extremely aggressive). For this purpose it is best to find light to moderate turbulence so the effects
can be properly observed. Having found suitable conditions, use the knob to gradually increase the value
of YD ACTIVITY in order to obtain an appropriate level of response to yaw disturbances. Too hig
value will result in rapid oscillation, while too low a value will essentially disable the quick response of
the yaw damper to turbulence. Within the acceptable range of operation, there is still room to account for
personal preferences. So long as the yaw damper’s ACTVTY value is not so high as to cause oscillation,
the response is simply set according to preference
the right knob twice to exit the setup mode.
The normal operation of the autopilot will turn the yaw damper on any time the autopilot is engaged and
the yaw damper will stay on after the autopilot is disengaged. During final approach and the diminishing
of the airspeed below the MIN AIRSPD setting, the yaw damper will automatically disengage. To
disengage the yaw damper prior to that point, simply use the YD button to toggle the yaw damper off.
April 2009 8300-057 Rev D