Vhf Nav Checkout (Gtn 650 Only); Vhf Com Checkout (Gtn 635/650 Only); Taws/Htaws System Check (For Units With Taws/Htaws Only) - Garmin GTN 625 Installation Manual

6.11.4

VHF NAV Checkout (GTN 650 Only)

While on the Map Page, touch the CDI key on the display to select VLOC mode, which is indicated by a
green 'VLOC' annunciation on the bottom center of the display. Check the VOR reception with ground
equipment, operating VOT or VOR, and verify audio and Morse code ID functions (if possible). Tune a
Localizer frequency and verify the CDI needle and NAV flag, and VDI needle and GS flag operation.
6.11.5

VHF COM Checkout (GTN 635/650 Only)

6.11.5.1 Antenna Check
If desired, the antenna VSWR can be checked using an inline wattmeter in the antenna coax using
frequencies near both ends of the band. The VSWR should be < 2:1. A VSWR of 2:1 will cause a drop in
output power of approximately 12%.
6.11.5.2 Receiver/Transmitter Operation
Tune the unit to a local VHF frequency and verify the receiver output produces a clear and understandable
audio output. Verify the transmitter functions properly by contacting another station and getting a report of
reliable communications.
6.11.6

TAWS/HTAWS System Check (For Units with TAWS/HTAWS Only)

While on the ground, turn on the GTN following normal power-up procedures. Also turn on the audio
panel.
NOTE
A 3D GPS position fix is required to conduct this check.
NOTE
HTAWS requires a helicopter specific, higher resolution terrain database. Without the
database, HTAWS will indicate a failure.
1. Touch the 'Terrain' key.
2. On the Terrain page, touch the 'Menu' key and select 'Test TAWS/HTAWS'.
3. Wait until the TAWS/HTAWS self-test completes (10-15 seconds) to hear the TAWS system status
aural message.
The aural message "TAWS/HTAWS System Test OK" will be annunciated if the 

TAWS/HTAWS system is functioning properly.
The aural message "TAWS/HTAWS System Failure" will be annunciated if the 

TAWS/HTAWS system is NOT functioning properly.
 If no audio message is heard, then a fault exists within the audio system and the TAWS/
HTAWS capability must be considered non-functional.
GTN 625/635/650 TSO Installation Manual
Page 6-60
190-01004-02
Rev. F