Ground Checks - Performance; Gps Reception (Internal Gps Receiver) - Garmin GTX 335 w GPS Installation Guidance

7.3 Ground Checks - Performance

Certain test procedures require the use of a Mode S transponder ramp tester such as an Aeroflex IFR-6000 or
TIC TR-220. Specific instructions for operating the ramp tester are contained in the applicable operator's
manual.
7.3.1

GPS Reception (Internal GPS Receiver)

NOTE
GPS reception checks are not necessary if an external GPS source is in use.
The GPS reception check is applicable to GTX 335 units with the internal GPS receiver.
1. Verify the LAT/LON on the ADS-B Out page matches a known reference.
2. Select 121.150 MHz on the COM transceiver to be tested.
3. Transmit for a period of 35 seconds.
4. Verify the GPS position remains valid.
5. Repeat steps 3 and 4 for these frequencies:
• 121.15 MHz
• 121.17 MHz
• 121.20 MHz
6. For VHF radios that include 8.33 kHz channel spacing, include the following frequencies in
addition to those in step 5.
• 121.185 MHz
7. Repeat steps 2 through 6 for all remaining COM transceivers in the aircraft.
8. Turn on the TCAS system and make sure the GPS position remains valid if the aircraft is TCAS
equipped.
9. Use the SATCOM system to make sure the GPS position remains valid if the aircraft is SATCOM
equipped.
190-00734-17
Rev. 1
• 121.22 MHz
• 121.25 MHz
• 131.20 MHz
• 121.190 MHz
• 131.22 MHz
• 131.25 MHz
• 131.27 MHz
• 130.285 MHz
GTX 335 w/GPS Installation Guidance
• 131.30 MHz
• 131.32 MHz
• 131.35 MHz
• 131.290 MHz
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