General Computers

The general computers system is at the center of the Garmin G1000H Integrated Avionics System (IAS). It links most helicopter systems and Line Replaceable Units (LRUs), and the Primary Flight Display (PFD) and Multi-Function Display (MFD). It consists of the integrated avionics unit (GIA) and the engine and airframe interface unit (GEA).

Integrated avionics unit (GIA)

The integrated avionics unit (GIA) is the central processor, processing data from all the sensors with a direct connection and from other systems through digital data busses for display of flight information. It also generates Crew Alerting System (CAS) messages.

The integrated avionics unit (GIA) provides these subassemblies (listed below) to the communication and navigation systems:

• VHF COM transceiver. For a system discussion and/or description, refer to Communications.

• Wide Area Augmentation System (WAAS) certified Global Positioning System (GPS) receiver. For a system discussion and/or description, refer to Navigation.

• VHF Omnidirectional Range (VOR)/Instrument Landing System (ILS) localizer receiver, and ILS glideslope receiver. For a system discussion and/or description, refer to Navigation.

The integrated avionics unit (GIA) is located on the avionics shelf in the aft center fuselage. It is mounted in a dedicated mounting rack to help replacement of the LRU when required.

Engine and airframe interface unit (GEA)

The engine and airframe interface unit (GEA) is mounted in a dedicated mounting rack to facilitate replacement of the LRU, when required. It monitors various engine and airframe mounted sensors and communicates with the integrated avionics unit (GIA) through a bidirectional digital data bus.

Some signals are duplicated in other systems to provide redundancy and are compared together to verify their proper operation.

The engine and airframe interface unit (GEA) is located on the avionics shelf in the aft center fuselage.

Operation

The integrated avionics unit (GIA) is energized with 28 VDC from the MAIN bus and can be isolated with the GIA SYS circuit breaker.

The engine and airframe interface unit (GEA) is energized with 28 VDC from the MAIN bus and can be isolated with the GEA circuit breaker.

Digital communications

The integrated avionics unit (GIA) (3141CM1) uses digital data busses to communicate with the systems that follow:

• The PFD and the MFD via a High Speed Data Bus (HSDB).

• The Engine Control Unit (ECU) via an ARINC-429 data bus.

• The Air Data/Attitude And Heading Reference System (ADAHRS) (GRS 77H) via an ARINC-429 and an RS-232 data bus.

• The transponder (GTX 33H) via an RS-232 data bus.

• The audio panel (GMA 350H) via an RS-232 data bus.

The integrated avionics unit (GIA) communicates with the engine and airframe interface unit (GEA) through the RS-485 data bus:

• The RS-485 1 A connection of the integrated avionics unit (GIA) is connected to the RS-485 1 A connections of the engine and airframe interface unit (GEA).

• The RS-485 1 B connection of the integrated avionics unit (GIA) is connected to the RS-485 1 B connection of the engine and airframe interface unit (GEA).

Integrated Avionics Unit (GIA) Discrete signals

The integrated avionics unit (GIA) processes the different discrete signals that follow:

• Electrical power

  • Starter on (EPSU)

  • Battery off (EPSU)

  • Generator fail (EPSU)

  • External power on (EPSU)

  • EPSU fail (EPSU)

• Baggage door

• Fire detection

• Fuel Level Sensor

  • Fuel Level Pro

  • Low level sensor

• Engine control

  • ECU fail

  • HMU Enabled

  • Throttle switch

• Main Rotor Drive Indicating

  • XMSN press low

  • XMSN temp high

• Chip detect

  • Free wheel

  • Upper MRD

  • Lower MRD

  • Tail Rotor

• WOG input

Engine and Airframe Interface Unit (GEA) Discrete signals

The engine and airframe interface unit (GEA) processes the different discrete signals that follow:

• Inlet Barrier Filter (IBF)

• Electrical power

  • Battery charging (BATT)

  • Battery fault (BATT)

  • Battery fail (BATT)

• Pitot heat on

• Main Rotor Drive Indicating

  • Upper MR chip Det Inop

  • Free wheel chip Det Inop

Engine and Airframe Interface Unit (GEA) Analog signals

The engine and airframe interface unit (GEA) processes the different analog signals that follow:

• Electrical power

  • Battery Temp (BATT)

  • Aircraft Voltage

  • Aircraft Current

• Engine Chip Detectors

• Fuel Level Sensor

  • Fuel Level Probe

• Rotor Speed

• Main Rotor Drive

  • XMSN Oil Temp

  • XMSN Oil Pressure

The signals are converted to a digital format for use by the processors. They are compared to verify the integrity of the different systems, and the integrated avionics unit (GIA) interfaces with the PFD and the MFD for display of the formatted data to the pilot and copilot.