Gsu 25D Earth Magnetic Field Updates; Special Inspection Requirements; Figure 2-5 - Gtp 59; Table 4-2 - Electrical Bonding Procedure - Garmin G3X Touch Maintenance Manual

Unit
GDU 4X0 (PFD)
GDU 4X0 (MFD) (if
installed)
GSU 25D (1)
GMU 11
GAD 29B
GAD 27
GEA 24
GDL 5XR
Notes:
(1) For remote mounted – it is bonded via the chassis mounting to aircraft ground.
For GDU-mounted – it is bonded via bonding strap to a ground stud
(2) This is the ground stud that the LRU bonding strap is connected to.
(3) For remote LRUs bonded to the back of the instrument panel via an installed aluminum foil ground plane,
the bonding measurement must be taken between the remote LRU and the instrument panel.

4.6 GSU 25D Earth Magnetic Field Updates

The GSU 25D utilizes an Earth magnetic field model which is updated once every five years. The IGRF
(International Geomagnetic Reference Field) update is expected to be available from Garmin in July 2020
and every five years thereafter, as long as the GSU 25D remains a Garmin-supported product.
The IGRF model is automatically updated with a GDU software update. The G3X system alerts the
operator the magnetic field database is out of date by issuing the message "AHRS SERVICE – AHRS
Magnetic-field model needs update". Garmin will distribute update instructions when updates are
available.

4.7 Special Inspection Requirements

After a suspected lighting strike, the following actions must be performed for the specific LRU.
GTP 59 Temperature Probe
Inspect the GTP 59 temperature probe for signs of lightning damage. Check the self-sealing washer (P/N
212-00026-00) used on the probe tip outside of the aircraft for any evidence of melting or lack of seal.
Replace the washer if damaged. If there is evidence of lightning strike to the GTP 59 temperature probe
or any lightning damage, replace the probe.
Tube-and-fabric aircraft must replace the GTP 59 bond strap (if installed) in accordance with Section 4 of
the G3X Touch EFIS Part 23 AML STC Installation Manual (190-02472-01).
G3X Equipment
All G3X equipment should be checked per Section 7. If equipment is not functioning correctly,
troubleshoot using information in Section 5. Contact Garmin Product Support before replacing G3X LRUs
to verify all troubleshooting options were exhausted.
Maintenance Manual
G3X Touch EFIS Part 23 AML STC
Table 4-2 – Electrical Bonding Procedure
Measurement Location (3)
J4X02 backshell to ground stud (2)
J4X02 backshell to ground stud (2)
Chassis mounting screw to adjacent aircraft ground
P251 backshell to ground stud (2)
P111 backshell to ground stud (2)
Chassis mounting screw to adjacent aircraft ground
Chassis mounting screw to adjacent aircraft ground
Chassis mounting screw to adjacent aircraft ground
P5X1 backshell to ground stud (2)
Page 30
Result
(milliohm)
mΩ
mΩ
mΩ
mΩ
mΩ
mΩ
mΩ
mΩ
190-02472-02
Revision 2