System Maintenance Manual

Page 2-6 G1000 / GFC 700 System Maintenance Manual - 200/B200 Series King Air
Revision 6 190-00915-01
2.1.8 GDC 74B Digital Air Data Computer (2)
The Garmin GDC 74B computers compile information from the pitot/static system and various outside air
temperature (OAT) and awareness sensors and provide digital air data computations to the G1000 system.
The GDC 74B communicates with the GIA 63W, GDU 1040A, and GRS 77 using ARINC 429 digital
interface. The unit is mounted behind the instrument panel. GDC 1 receives primary electrical power from
the Essential Bus and a secondary power supply from Dual Fed Bus No. 1. GDC 2 receives power from
Dual Fed Bus No. 2. GDC 1 and GDC 2 connect to existing pitot/static ports. Refer to Figure 2-20 for a
schematic of the aircraft’s pitot/static system and its connections to the G1000 STC installed equipment.
IMPORTANT!
Aircraft modified by this STC are eligible to be approved for RVSM operation. RVSM
critical maintenance instructions contained in this document must be followed in order
to guarantee performance within RVSM specifications.
Figure 2-8, Air Data Computer
2.1.9 OAT Probe (2)
The Garmin GTP 59 OAT Probes provide the GDC 74B with air temperature data. The OAT probes are
mounted to the bottom of the fuselage at F.S. 113.5.
Figure 2-9, OAT probe