Technical data

13773-001
34-50
Page 1
DEPENDENT POSITION DETERMINING
1. DESCRIPTION
This section covers that portion of the system which provides information to determine position from
sources which are mainly dependent on ground installations. This includes the Garmin GNS 430 GPS/
COM/NAV, Garmin GTX 327 Transponder system, and VOR/LOC Antenna.
The Garmin GTX 327 Transponder, located mid-avionics panel, receives interrogations from a ground-
based secondary radar transmitter and transmits the airplane’s identification to the Air Traffic Control Cen-
ter via Mode A transmissions and altitude information via Mode C. Refer to GTX 327 Installation Manual
indexed in the front of this manual for additional maintenance information on the GTX 327
2. MAINTENANCE PRACTICES
A. Garmin GNS 430 GPS/COM/NAV
The GNS 430 is an IFR certified VHF communications transceiver and Navigation Management Sys-
tem (NMS). The NMS includes GPS sensor, VOR/Localizer and Glideslope receivers. The GNS 430
includes two removable data cards, one with a Jeppesen data base, and second being a custom data
card. GPS signals are received by an internally mounted antennas. NAV/LOC/GS signals are received
by the VOR/LOC antenna. For installation and removal procedures refer to Independent Position
Determining. (Refer to 34-40)
B. Garmin GTX 327 Transponder (See Figure 34-501)
(1) Removal - Garmin GTX 327 Transponder
(a) Ensure BAT 1, BAT 2, and AVIONICS master switches are in off position.
(b) Pull ENCODER/TRANSPONDER circuit breaker.
(c) Insert hex wrench into front panel bolt hole and engage hex bolt.
(d) Turn locking screw counterclockwise to loosen locking cam. Locking cam will move the
transponder unit out 1/4” and disengage from the electrical connectors.
(e) Pull transponder from mounting tray and remove from airplane.
(2) Installation - Garmin GTX 327 Transponder
(a) With light to medium pressure, push transponder into mounting tray to engage electrical
connectors.
(b) Insert hex wrench into front panel bolt hole and engage hex bolt.
(c) Turn bolt clockwise to tighten locking cam.
(d) Reset ENCODER/TRANSPONDER circuit breaker.
C. Transponder Antenna (See Figure 34-501)
(1) Removal - Transponder Antenna
(a) Remove access panel CF8. (Refer to 6-00)
(b) Disconnect antenna cable from antenna.
(c) Ensure transponder antenna is supported and remove nut and washer securing antenna
to fuselage belly.
(d) Remove antenna from airplane.
(2) Installation - Transponder Antenna
(a) Ensure transponder antenna is inserted and supported in antenna mounting hole in fuse-
lage belly.
(b) Install washer and nut securing antenna to fuselage belly.
(c) Connect antenna cable to antenna.
(d) Install access cover CF8. (Refer to 6-00)
31 July 2001