190-01115-01 G3X/G3X Touch Installation Manual - MaintenanceRev. AC Page 36-136 MAINTENANCE36.1 Inspections/Continued Airworthiness/MaintenancePeriodic maintenance of most G3X LRUs is not required and is “on condition” only. Instructions forContinued Airworthiness (ICA) are not required per 14 CFR Part 21 for these products as they havereceived no FAA approval or endorsement. Garmin recommends that the G3X LRUs be inspected forproper operation, secure attachment, integrity of connectors and wiring, cleanliness, leakage of hoses andtubes, and any evidence of damage as part of the required annual or periodic aircraft inspection. For moregeneral inspection guidance, please refer to the applicable sections of CFR Part 43 Appendix D andChapter 12 of AC 43.13-1B. For ADAHRS Static Pressure Calibration, refer to Section 33.4.3 forGDU 37X or Section 34.4.5 for GDU 4XX.LRUs that require periodic maintenance are listed in the following subsections.36.1.1 GAP 26Garmin recommends that a leak test (Section 5.5.5) be performed following any maintenance action inwhich the pitot or AOA pneumatic lines are opened up (i.e. whenever the GAP 26 is removed or replaced).36.1.2 GSU 25Per Part 43 Appendix E, paragraph (b)(2), Garmin recommends a test procedure equivalent to part 43Appendix E, paragraph (b)(1) with two exceptions. The tests of sub-paragraph (iv) (Friction) and (vi)(Barometric Scale Error) are not applicable because the digital outputs of the GSU 25 are not susceptible tothese types of errors. This procedure is recommended when the static system is opened up (i.e. wheneverthe GSU 25 is removed or replaced). Garmin also recommends that a leak test be performed following anymaintenance action in which the pitot or AOA pneumatic lines are opened up (i.e. whenever the GSU 25 isremoved or replaced).The GSU 25 utilizes an Earth magnetic field model which is updated once every five years. This IGRF(International Geomagnetic Reference Field) update is expected to be available from Garmin in July of2020 and every five years thereafter, so long as the GSU 25 remains a Garmin –supported product. TheIGRF model is automatically updated with a GDU software update. Otherwise maintenance of theGSU 25 is ‘on condition’ only.NOTEIf the GSU 25 is moved or replaced, the Post Installation Calibration Procedures(Section for GDU 37X systems and Section for GDU 4XX systems) must be repeated.
