GRT Avionics, Inc.
May 2019
Sport EX/Horizon EX Install. Manual
26
Rev. A
5-12: Fine Magnetometer Calibration Procedure
The magnetometer must be calibrated before the first flight of the aircraft. Magnetometer
calibration is required to achieve accurate magnetic heading readings. This calibration
corrects for errors induced by magnetic disturbances local to the sensor, such as ferrous
metal objects.
*NOTE:
The AHRS will not allow magnetometer calibration to be initiated if the airspeed
is greater than 50 mph to prevent inadvertent selection while in-flight. If calibration is
successful, the existing calibration data (if any) will be replaced with the new corrections.
The Magnetometer Calibration page will help guide you through this procedure with its
on-screen menus and prompts.
*NOTE:
Before performing this procedure, be sure that the AHRS orientation and
magnetometer orientation have been set. If these are not performed, the magnetometer
calibration will produce inaccurate magnetic heading readings.
1. Point the aircraft to magnetic north in an area without magnetic disturbances, such
as a compass rose.
A simple means of pointing the airplane toward magnetic north is to taxi the
airplane slowly and use the GPS ground track to determine when you are taxiing
in a magnetic north direction (the GPS cannot determine your track unless you are
moving). Note the precise indication on the backup whiskey compass. Stop the
airplane and adjust its heading to the reading observed on the whiskey compass.
2. After the aircraft is positioned correctly, turn ON the GRT Sport EX/Horizon EX (If
it was already on, then turn it OFF, and then back ON again).
3. Allow at least 1 minute for the AHRS to fully stabilize.
4. Press any button on the EFIS display to bring up the soft key labels. Press the SET
MENU soft key, and then scroll to and select AHRS Maintenance. Scroll to and
select the
“Magnetometer Calibration” field on this screen.
5. Press Start soft key.
6.
The first question is “Are you sure?” Press YES if you are sure.
7. Verify that
the airplane is still pointed to magnetic north. Answer the question “Are
the aircraft, AHRS, and magnetometer pointing to m
agnetic north?” with YES. A
message will appear at the bottom of the screen indicating that the system is
waiting for the gyros to stabilize.
