190-02081-03
GFC 600H HFCS Part 27 STC Maintenance Manual
Rev. 3
Page 2-13
The following functions are dependent upon this sensor input:
• IAS Hold
• FD availability
• VS Hold
• Altitude Hold
• AHRS Aiding
• Limit Cue / Speed Protection Modes
• VNE Calculation
• In-air / On-ground logic
2.2.6.3 OAT Probe
The GTP 59 is an outside air temperature probe that interfaces to the ADC. The OAT data is sent to the
ADC for use in true airspeed computations. The GTP 59 is mounted externally on the rotorcraft.
Figure 2-8 GTP 59 OAT Probe
2.2.6.4 AHRS/ADAHRS Interfaces
GRS 79H and GSU 75H support various digital system I/O. The system supports ARINC 429, RS-232,
RS-485, and CAN communications interfaces. The following list summarizes the available I/O for these
LRUs.
GMU 44( )
• GMU 44( ) to GRS 79H or GSU 75H Interface: Power, RS-232, RS-485
• GMU 44( ) interface to GMC 605H is only RS-485
GRS 79H
• Six ARINC 429 AHRS (Attitude and Heading Reference System) Inputs (individually selectable
high or low speed)
• Six ARINC 429 AHRS (Attitude and Heading Reference System) Outputs (High Speed; three
Independent, Redundant)
• RS-232 AHRS Inputs/Outputs from Garmin GPS source
• One CAN Bus
• PPS Inputs
• Discrete Inputs
• Two System ID Program pins
• Two Aircraft Power Inputs
