Additional Ground Tests - Garmin GNC 420A Installation Manual

5.3

ADDITIONAL GROUND TESTS

5.3.1 Connector Engagement Test
1. Turn on the 400 Series unit, and turn on the avionics master switch (if applicable).
2. Place the 400 Series unit in the rack and engage the pawl mechanism.
3. Turn the Allen screw of the locking pawl slowly clockwise until the 400 Series unit just comes on. A
"T" handle makes the turns easy to count, but do not over-tighten.
4. Count the number of complete revolutions you can turn the Allen screw until it can not turn any more
(but take care not to over-tighten). Three turns is the minimum for proper installation. If fewer than
three turns are possible, the mounting rack should be moved aft such that the aircraft panel does not
obstruct the unit from engaging in the rack.
5.3.2 Verification of Self-Test Data
Following normal power-up, the Self-Test Page is displayed followed by the Data Base Page. Pressing the
ENT key once then displays the Instrument Panel Self-Test page (refer to Figure 5-5 on page 5-5). During
this time, many of the electrical outputs are activated so the installation, configuration, and wiring may be
verified. Before approving the Data Base Page, verify that the following parameters are displayed on
equipment in the aircraft as listed below:
Electronic displays which monitor the 400 Series unit's ARINC 429 output may vary in how and where
annunciations are displayed. Generally, it is not required to verify every data field with an ARINC 429
interface. Correct display of a subset of the data without noting any discrepancies is typically adequate
evidence of correct ARINC 429 operation.
Parameter
Course Deviation
Glideslope/Vert. Deviation
Bearing to Waypoint
Desired Track
Selected Course
Distance to Go
Time to Go
Active Waypoint
Groundspeed
Present Position
Waypoint Alert
Phase of Flight
Message Alert
Leg/OBS Mode
GPS Integrity
5.3.3 Signal Acquisition Test
Upon approval of the Data Base Page, the Satellite Status Page is displayed. If the unit is unable to acquire
satellites, relocate the aircraft away from obstructions which might be interfering with GPS reception. If
the situation does not improve, check the GPS antenna installation.
Once GPS position information is available, use the DIRECT-TO key to activate the navigation function to
a nearby airport, NAVAID, or intersection. Ensure that any connected equipment is transmitting and
or/receiving data from the 400 Series unit and is functioning properly (see the Pilot's Guide for more
information on the direct-to function).
Page 5-16
Page Rev L
NOTE
Self-test Value
Half-scale left deviation, TO indication, flag pulled
Half-scale up deviation, flag pulled
135º
149.5º
149.5º
10.0 nautical miles
4 minutes
"GARMN"
150 knots
N 39º04.05', W 94º53.86'
Active
En Route
Active
Leg Mode
Reflects actual GPS integrity
400 SERIES INSTALLATION MANUAL
P/N 190-00140-02