Mounting Requirements - Garmin GSU 75 Series Installation Manual

2.11 Mounting Requirements

2.11.1 GSU 75 Mounting
The GSU 75 includes an extremely sensitive strap-down inertial measurement unit. It must be mounted
rigidly to the aircraft primary structure. Do not use shock mounting. Shock mounts used for other types of
inertial systems are not acceptable for the GSU 75 ADAHRS. The mounting system must have no
resonance with the unit installed that would cause DO–160F vibration levels to be exceeded. (See the
GSU 75 Environmental Qualification Form). Vibration outside of these limits may result in degraded
accuracy.
The supporting plate must be rigidly connected to the aircraft primary structure through strong structural
members capable of supporting substantial loads. Avoid areas that are prone to severe vibration (e.g.,
areas close to engine mounts and landing gear).
The GSU 75 should be mounted within 13 feet longitudinally and 6.5 feet laterally of the aircraft center of
gravity. The mounting location for the GSU 75 should be protected from rapid thermal transients, in
particular, large heat loads from nearby high-power equipment.
The GSU 75 mounting rack should be leveled to within 8° in aircraft longitudinal direction (pitch), and 4 °
in aircraft lateral direction (roll) with the unit oriented such that the rack is on the bottom, and an aircraft
leveling and offset setting procedure carried out prior to flight. (This procedure is described in Section 5)
Alternatively, if the mounting rack can be guaranteed level to within 0.25° of the aircraft level reference,
the aircraft leveling and offset setting procedure is not required.
In regards to heading, the GSU 75 supports mounting in the four azimuth orientations orthogonal to the
direction of flight (i.e., connector forward, aft, left, or right) and must be aligned within ±1.0° of the
applicable axis to avoid heading errors. The mounting orientation will be stored in the aircraft specific
configuration module.
Refer to Appendix A Outline and Installation Drawing for details.
190-01639-00 GSU 75 ADAHRS Installation Manual
Rev. 6 Page 2-6
340095
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