190-02207-A2
GPS 175/GNX 375/GNC 355 Part 23 AML STC Maintenance Manual
Rev. 3
Page 4-3
4.2 Servicing Information
The GPS 175, GNX 375, and GNC 355 do not require servicing. In the event of system failure,
troubleshoot the GPS 175/GNX 375 in accordance with Section 5.
4.2.1 Periodic Maintenance
The GPS 175/GNX 375/GNC 355 are designed to detect internal failures. A thorough self-test is executed
automatically upon application of power to the units. The built-in tests (BIT) are continuously executed.
Detected errors are indicated as failure annunciations, system messages, or a combination of the two.
Antenna installations are not covered under this STC. Inspect and maintain all antennas in accordance with
the data provided for that specific antenna installation.
4.2.2 Special Tools
A milliohm meter with an accuracy of ±0.1 mΩ (or better) is required to measure the electrical bonding
between the GPS 175/GNX 375/GNC 355 system components and aircraft ground.