TruTrak Pictorial Pilot - Manual (Page 16)

Magnetic Calibration
The Pictorial Pilot autopilot contains a built-in magnetometer which is used to maintain gyro centering and slaving for the
built-in Electronic DG of the autopilot in case of GPS loss. This magnetometer is calibrated at the factory in a disturbance-free
environment, but once installed in the aircraft it may be necessary to account for any fixed magnetic disturbances in the aircraft
itself.
For best results, this operation should be done on a day when the winds are relatively calm, so that air is still and heading and
ground track are approximately the same in all directions. The operation should be deferred until such flight conditions exist.
For this operation the autopilot will fly four legs of approximately half a minute each, first north, then east, then south, then
west. Prior to the calibration sequence, fly the aircraft to an area where this can suitably be done. Verify that the autopilot is
receiving GPS properly (note that the digital DG appears in the display when the autopilot is off, and the selected ground track
appears when the autopilot is on). Choose and hold an appropriate altitude and engage the autopilot using the knob or the
control stick switch. During the calibration sequence, it is important that aircraft pitch attitude remain as constant as possible.
Once the autopilot is engaged, press and hold the knob for approximately 4 seconds until the first setup screen appears. Click
the knob four times, to cycle through the activity, torque, micro activity, and baud rate setup screens until the fifth setup screen
shows on the display. This will be a flashing digit “4” followed by the digit “0”. Rotate the knob to select 1 (for “yes”) and
then click the knob. The autopilot screen will announce the beginning of the calibration sequence with the digits “000” flashing
as it turns the aircraft towards North. It will fly the aircraft to a ground track of 000 degrees, and once established on course the
digits will cease flashing as the autopilot gathers and averages magnetometer readings for this direction. This process requires
approximately ten to twenty seconds of steady flight on a ground track of 000 degrees. Having gathered the required data, the
autopilot will announce its turn towards East with a flashing “090” display. Again, the autopilot rolls out and gathers data. This
process is continued through South, and finally West. Having completed this operation, the display will change to “– C –”
indicating that calibration has been successful. (A display of “– F –” at any time during the magnetic calibration sequence
means that the GPS signal has been lost and the calibration cannot be completed. Repeat the calibration once reliable GPS
reception is again present.) Confirm the calibration sequence by clicking the knob. At this point, the autopilot will revert back
to its normal flight mode with a direction selector, but it now has a magnetic backup mode sufficient to fly the aircraft drift-free
in the event of GPS loss.
TruTrak Flight Systems Pictorial Pilot Installation & User Guide
December 2009 14 8300-011 Rev B