Required Distance From Magnetic Disturbances - Garmin G3X Installation Manual

Table 8-4 Required Distance from Magnetic Disturbances
Electric motors and relays, including servo motors
Ferromagnetic structure greater than 1 kg total (iron, steel, or cobalt materials,
especially landing gear structure)
Ferromagnetic materials less than 1 kg total, such as control cables
Any electrical device drawing more than 100 mA current
Electrical conductors passing more than 100 mA current [(must be twisted
shielded pair if within 10 feet (3.0 meters)]
Electrical devices drawing less than 100 mA current
Magnetic measuring device (e.g. installed flux gates, even if unpowered)
Electrical conductors passing less than 100 mA current [(must be twisted
shielded pair if within 10 feet (3.0 meters)]
Ensure that any electrical conductor that comes within 10 feet (3.0 meters) of the GMU 22 is installed as a
twisted shielded pair, not a single-wire conductor. (If possible, the shield should be grounded at both
ends.)
Use nonmagnetic materials to mount the GMU 22, and replace any magnetic fasteners within 0.5 meter
with nonmagnetic equivalents (e.g. replace zinc-plated steel screws used to mount wing covers or wing tips
with nonmagnetic stainless steel screws).
In general, wing mounting of the GMU 22 magnetometer is preferred (unless as noted in
Fuselage mounting is less desirable because of numerous potential disturbances that interfere with accurate
operation.
Mechanical mounting fixtures for the GMU 22 must be rigidly connected to the aircraft structure. Use of
typical aircraft-grade materials and methods for rigid mounting of components is acceptable, so long as
adequate measures are taken to ensure a stiffened mounting structure.
Level the GMU 22 mounting rack to within 3.0° of the in-flight level cruise attitude.
Align the GMU 22 mounting rack's forward direction to within 0.5° of the longitudinal axis of the aircraft.
In a system with more than one ADAHRS (GSU 25/73), ADAHRS 1 must be connected to a GMU22, but
installing additional GMU 22 units for other GSU 25 ADAHRS units is optional. An ADAHRS without a
GMU 22connected will use magnetometer data supplied by other ADAHRS as long as they are both
communicating via CAN.
190-01115-01
Rev. L
Disturbance Source
G3X Installation Manual - GMU 22 Installation
Minimum Distance
from GMU 22
10 feet (3.0 meters)
8.2 feet (2.5 meters)
3 feet (1.0 meter)
3 feet (1.0 meter)
3 feet (1.0 meter)
2 feet (0.6 meter)
2 feet (0.6 meter)
1.3 feet (0.4 meter)
Appendix A).
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