190-02207-A2
GPS 175/GNX 375/GNC 355 Part 23 AML STC Maintenance Manual
Rev. 3
Page 6-6
6.3 GNC 355
6.3.1 GNC 355 Removal
1. Locate and open the GNC 355 circuit breaker.
2. Locate the unit retention mechanism access hole at the top-right corner of the unit face.
3. Insert a 3/32” hex tool into the access hole and turn the fastener counterclockwise until the unit is
forced out about 3/8” and the hex drive tool stops completely.
4. Slide the GNC 355 out of the rack.
6.3.2 GNC 355 Re-installation
NOTE
It may be necessary to insert the hex drive tool into the access hole and turn the cam
mechanism 90° counterclockwise to ensure correct position prior to placing the unit in the
rack.
CAUTION
Be sure not to overtighten the unit into the rack. The application of hex drive tool torque
exceeding 15 in-lbf can damage the locking mechanism.
1. Ensure that the GNC 355 circuit breaker is open.
2. Slide the GNC 355 straight back into the rack until it stops about 1/8” short of the fully seated
position.
3. Insert a 3/32” hex drive into the unit retention mechanism access hole at the top right of the unit.
4. Turn the tool clockwise while pressing on the left side of the bezel until the unit is firmly seated in
the rack.
5. Once the GNC 355 is re-installed, verify that the unit power-up self-test sequence is successfully
complete and no failure messages or configuration error messages are annunciated. Section 6.4
outlines the power-up self-test sequence.
