Altitude Encoder Or Air Data Computer Check; Ahrs/Iru Interface Check; Figure 6-45. Main Data Inputs Page - Garmin GTN 635 Installation Manual

6.10.10 Altitude Encoder or Air Data Computer Check

The GTN can receive altitude data from an external source. This check verifies that the GTN is receiving
data from these sources. Ensure that the GTN is powered on and in configuration mode. If the following
steps do not perform correctly, check the electrical connections (Appendix D) and configuration setup
(Section 6.6.2) for the interfaced Altitude encoder/ADC.
1. Access the Main Data Inputs page, as shown in
Figure 6-45, by touching the ‗Main Data Inputs' key on
the GTN Diagnostics page.
2. Touch the ‗Down' key to scroll to the Pressure Altitude
data display.
3. If there are multiple altitude sources providing data to the
GTN, remove power from all but one source.
4. Verify that Pressure Altitude is being displayed and
agrees with the active altitude source.
After applying power to an altitude source it may take several minutes to warm up.
During the warm-up period the Pressure Altitude display on the GTN will be dashed out.
5. If there are multiple altitude sources, remove power from the currently active source and
apply power to another source that has not been checked.
6. Repeat steps 2-4 until all available sources have been checked.

6.10.11 AHRS/IRU Interface Check

The GTN can receive heading data from an external source. This check verifies that the GTN is receiving
data from these units. Ensure the GTN is powered on and in configuration mode. If the following steps do
not perform correctly, check the electrical connections and configuration setup for the interfaced
AHRS/IRU.
1. Access the Main Data Inputs page, as shown in Figure 6-45, by touching the ‗Main Data Inputs'
key on the GTN Diagnostics page.
2. Scroll to the Magnetic Heading data display.
If a Sandel EHSI or an ARINC 429 EFIS is also installed, ensure that it is turned off so
that it does not supply heading to the GTN. Verify that the HDG field displays valid
heading data.
3. Remove power from the heading source and verify that the magnetic heading field is dashed out.
Page 6-36
Rev. C
NOTE
NOTE

Figure 6-45. Main Data Inputs Page

GTN 625/635/650 TSO Installation Manual
190-01004-02