190-01115-01
G3X/G3X Touch Installation Manual - GSU 25/25B Installation
Rev. AC
Page 18-5
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The GSU 25 must be mounted rigidly to the aircraft primary structure through strong structural
members capable of supporting substantial loads, see torque specification listed on
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The supporting plate must be rigidly connected.
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The GSU 25 should be mounted within 13 feet (4.0 meters) longitudinally and 6.5 feet (2.0 meters)
laterally of the aircraft CG (center of gravity). In cases where the longitudinal distance from the
CG is planned to be greater than 6.5 feet (2.0 meters), it is preferable to mount the GSU 25 forward
of the aircraft CG if possible, to enable better acceleration outputs for autopilot use.
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Avoid placing the GSU 25 near sources of vibration or audible noise. Examples locations to be
avoided include the engine firewall, near large motors or fans, and audible buzzers and speakers.
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Do not mount the GSU 25 in an enclosed area, it should be mounted in a location that provides
adequate airflow.
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Avoid areas that are prone to severe vibration. Excessive vibration may result in degraded
accuracy.
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Do not use shock mounting to mount the GSU 25. Shock mounts used for other types of inertial
systems are not acceptable for the GSU 25 AHRS. The mounting system must have no resonance
with the unit installed. The unit and mounting structure must not have any resonance with respect
to the aircraft primary structure.
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The wing is not an optimal location to mount the unit as (in addition to being away from the center
of gravity) any amount of wing flex will directly translate into attitude error.
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The GSU 25 must be leveled to within 30.0° of the in-flight level cruise attitude and an aircraft
leveling and offset calibration procedure carried out prior to flight. (This procedure is described in
for GDU 37X systems and
for GDU 4XX systems.)
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The mounting location for the GSU 25 should be protected from rapid thermal transients, in
particular, large heat loads from nearby high-power equipment.
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Avoid placing the GSU 25 within 1 inch of magnetically mounted antennas, speaker magnets, or
other strongly magnetic items.
NOTE
Select the “Tubes Forward/Connectors Down” orientation when the GSU 25 is mounted
to the back of the GDU 4XX unit.
Figure 18-2 AHRS Orientation Selection
