Maintenance Manual 190-02472-02G3X Touch EFIS Part 23 AML STC Revision 2Page 415.4.4 Magnetometer Interference TestNOTEThe Magnetic Interference Test is only required for initial installation verification. This test should also berepeated to verify all subsequent electrical changes associated with devices within 10 feet of the GMUmagnetometer. Such changes include, but are not limited to, wiring, shielding, or grounding changes toany light, strobe, beacon, or other electrical device located in the vicinity of the GMU magnetometer unit.Likewise, this test should also be repeated to verify all subsequent changes to materials within 10 feet ofthe GMU magnetometer. Such changes include but are not limited to addition, removal, or modificationof ferrous or electrically conductive materials located in the same wing as a GMU magnetometer unit.This procedure validates that no electronic device is interfering with the operation of the GMUmagnetometer which directly impacts the determination of attitude and heading by the GSU 25D. TheADAHRS Unit Orientation and Pitch/Roll Offset Compensation are not required prior to this execution ofthis procedure. A sequence of activities to be performed during a magnetometer interference test isshown in Table 5-7 below. This is an example to help guide a technician through an aircraft’s functionsthat may create interference with an installed GMU 11 magnetometer.CAUTIONThe real time readout displayed during the interference test is only valid for the location of the GMUwhen the test was initiated. If using this procedure to evaluate multiple mounting locations, the test mustbe started over for each location, failure to do so could provide incorrect test results.1. Power on PFD in configuration mode (Section 3.2.2).2. Select the Magnetometer Calibration Page.3. Select Magnetic Interference Test.4. Ensure that the aircraft has been properly prepared per the on-screen instructions. See Table 5-7 fora sample test sequence. Press the Start button to begin the test.Figure 5-6 – Magnetometer Interference Test On-screen Instructions5. The actions must be carried out as called for in the prepared test sequence. During calibration, areal-time value is displayed that represents the current magnetic field strength as a percentage ofthe maximum limit.
