Pilot's Guide

190-00663-03 Rev. A
Garmin G1000 Pilot’s Guide for the Beechcraft C90A/GT/GTi
3
SYSTEM OVERVIEW
• GDC 74B (2) – Processes data from the pitot/static system as well as the OAT probe. This unit provides pressure
altitude, airspeed, vertical speed and OAT information to the G1000 system, and it communicates with the on-
side GIA 63W, on-side GDU 1040A, GDU 1040A MFD, and on-side GRS 77/7800, using an ARINC 429 digital
interface (it also interfaces directly with the on-side GTP 59). The GDC 74B is designed to operate in Reduced
Vertical Separation Minimum (RVSM) airspace.
• GEA 71 (2) – Receives and processes signals from the engine and airframe sensors. This unit communicates
with both GIA 63Ws using an RS-485 digital interface.
• GRS 77/7800 (2) – Provides aircraft attitude and heading information via ARINC 429 to both the on-side
GDU 1040A, the GDU 1040A MFD, and the on-side GIA 63W. The GRS 77/7800 contains advanced sensors
(including accelerometers and rate sensors) and interfaces with the on-side GMU 44 to obtain magnetic field
information, with the GDC 74B to obtain air data, and with both GIA 63Ws to obtain GPS information. AHRS
modes of operation are discussed later in this document.
• GMU 44 (2) – Measures local magnetic field. Data is sent to the GRS 77/7800 for processing to determine
aircraft magnetic heading. This unit receives power directly from the GRS 77/7800 and communicates with the
GRS 77/7800, using an RS-485 digital interface.