Grs 77 Attitude Heading Reference System And Gmu 44 Magnetometer; Gdc 74A Air Data Computer; Gea 71 Engine Monitor; Gtx 33 Transponder - Cessna 172S NAV III Pilot Operating Handbook

SECTION 7
AIRPLANE AND SYSTEMS DESCRIPTION
STANDARD AVIONICS
(Continued)
CESSNA
MODEL 172S NAV III
GRS 77 ATTITUDE HEADING REFERENCE SYSTEM (AHRS)
AND GMU 44 MAGNETOMETER
The GRS 77 AHRS provides airplane attitude and flight
characteristics information to the G 1 000 displays and to the G lA 63
units. It is located in the tailcone of the airplane. The unit contains
accelerometers, tilt sensors and rate sensors that replace spinning
mass gyros used in other airplanes. The GMU 44 Magnetometer is
located inside the left wing panel. It interfaces with the AHRS to
provide heading information.
GDC 74A AIR DATA COMPUTER
The GDC 74A Air Data Computer (ADC) compiles information from
the aircraft's pitoVstatic system. The unit is mounted behind the
instrument panel, just forward of the MFD. An outside air
temperature probe, mounted on top of the cabin, is connected to the
Air Data Computer. The ADC calculates pressure altitude, airspeed,
true airspeed, vertical speed and outside air temperature.
GEA 71 ENGINE MONITOR
The GEA 71 Engine Monitor is responsible for receiving and
processing the Signals from all of the engine and airframe sensors.
It is connected to all of the cylinder head temperature measuring
sensors, exhaust gas temperature sensors, RPM, fuel flow and to
the fuel gauging system. This unit transmits this information to the
GIA 63 computers.
GTX
33
TRANSPONDER
The GTX 33 is a full-featured Mode S transponder which provides
Mode A, C and S functions. Control and operation of the '-'
transponder is accomplished using the PFD. The GTX 33 unit is
mounted in the tailcone avionics racks.
Additional standard avionics supplied for use with the G 1 000
Integrated Cockpit System include:
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U.S. 172SPHAUS-03