The integrated-avionics processor system (IAPS) helps connect the different avionics systems on the aircraft. The IAPS holds avionics line replaceable units (LRUs). The IAPS is divided to independently transmit signals more than once, and each part has independent power. The IAPS also reads some avionics busses and sends data words to the LRUs that use that data. The IAPS performs ARINC data processing and distribution for avionics LRUs.

The IAPS is a housing that holds some units. The input/output concentrator units (IOCs) get data words and transmit them to the correct LRU. The IAPS power supplies (PWRs) energize the IOCs. The IAPS environmental controller (IEC) monitors the housing temperature and controls its heaters and fans. The control strapping units (CSUs) and the options control modules (OCMs) set the IAPS strap settings.

The maintenance diagnostic computer (MDC), the flight management computers (FMCs), and the flight guidance computers (FGCs) are in the IAPS card cage (ICC), but they are not part of the IAPS itself.

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The ICC is the housing that contains all of the other components of the IAPS. The ICC is in the RH equipment rack. The connections to/from the IAPS with the external systems are on the outboard side of the ICC. There is a circuit card that connects all LRUs in the IAPS. There are two temperature transducers on the circuit card that give IAPS temperature to the IEC. The ICC has two internal sides. The 1A half (left side) is the section from the IEC to the first IOC. The 2A half (right side) is the section from the MDC to the second IOC. The ICC is lightning/high intensity radiated field (HIRF) protected.

The LRUs installed in the ICC are locked into position with tabs at the top and the bottom of the LRUs. The ICC cover has rubber bumper strips on the inside. When the cover is attached, the rubber bumper strips hold the module tabs in the closed position. The cover of the ICC housing attaches to the ICC with captive fasteners.

Aircraft Power

The left side of the IAPS card cage gets power from the L ESS BUS. The L IAPS CB1-B6 circuit breaker on the left circuit breaker panel (LCBP) provides circuit protection.

The IEC gets power from the L MAIN BUS. The IAPS FAN CB3-E1 circuit breaker on the left secondary power center (LSPC) provides circuit protect.

The right side of the IAPS card cage gets power from the R ESS BUS. The R IAPS CB2-B6 circuit breaker on the right circuit breaker panel (RCBP) provides circuit protection.

 

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IAPS data comes from and goes to many external systems. External system data is transmitted through the ICC circuit card.

The two IOC transmit data, to other LRUs, that is related to their operation. The IOCs collect and transmit diagnostic words to the MDC. The IOCs transmit concentrator data to the FGCs. The IOCs transmit all the display data from other LRUs to the displays.

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The IAPS receives 28 VDC electrical power from the L ESS BUS and R ESS BUS. The voltage is filtered, then it is applied to the PWRs. The two PWRs independently supply the applicable voltages to the necessary units in the IAPS. The No. 1 PWR energizes the No. 1 FGC, FMC, and IOC No. 1. The No. 2 PWR energizes the No. 2 FGC, FMC, MDC, and IOC unit No. 2.

The 28 VDC supplied to the No. 1 PWR is electromagnetic interference (EMI) filtered. This voltage is not related to the 28 VDC levels applied to the No. 2 PWR. The PWRs supply the voltages that follow:

• 5 VDC
• 28 VDC
• 12 VDC
• -12 VDC

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The IEC controls the temperature for the ICC. The IEC monitors a pair of ICC temperature sensors. It operates an internal heater and a two speed fan to keep a correct temperature in each half of the IAPS.

The IEC has a power supply, two thermostats, two transducer monitor circuits, a two speed fan, and a heat exchanger. The IEC receives 28 VDC electrical power from the L MAIN BUS.

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The two CSUs set the system configuration discretes for the aircraft. Each CSU supplies configuration strapping for one half of the IAPS. Also, the CSUs supply strapping for the IOC. The CSU provides a large number of switches (ground/open) which are read by the IOCs. Some straps do not exist on the CSU and are part of the individual LRU.

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The two OCMs are installed on the CSUs. The OCMs give protected strapping for the configuration word zero. The OCMs protected strapping can not be changed. Each OCM has 16 digital words (label 360) that set the configuration strapping for the configuration word zero, based on the aircraft part number status.

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Inputs and Outputs

The IOCs receive data words from the LRUs. All data inputs from external systems go through a protection circuit to give filtered data. The two IOCs receive data inputs from the units and systems that follow:

• Adaptive Flight Display Unit (MFD, PFD)
• Air Data Computer (ADC)
• Automatic Flight Control System (AFCS)
• Control Display Unit (CDU)
• Data Concentration Unit (DCU)
• Flight Guidance Computer (FGC)
• Flight Management Computer (FMC)
• File Server Unit (FSU)
• Global Positioning System (GPS)
• Horizontal Stabilizer Trim Control Unit (HSTECU)
• Inertial Reference Unit (IRU)
• Maintenance Diagnostic Computer (MDC)
• Proximity Sensor Electronic Unit (PSEU)
• Radio Altimeter Transceiver
• Radio Interface Unit (RIU)
• Stall Protection Computer
• Synthetic Vision Computer (SVC)
• Terrain Avoidance Warning System (TAWS)
• Traffic Surveillance System (TSS) and Transponder Unit
• Air Traffic Control (ATC) Transponder Unit
• Weather Radar Transceiver
• Autothrottle Computer Autothrottle (A/C 20875 to 20936 post SB350-22-002, and A/C 20937 and Subs)

The LRUs transmit data through the IOC that is related to a different LRU:

• The ADC transmits pitch and roll attitude, heading, body rate, and linear acceleration parameters
• The CDU transmits radio tune data
• The DCU transmits the engine and aircraft data
• The FGC transmits reference altitude, reference speeds, roll and pitch outputs, flight director mode, steering data, display data, and air data system (ADS) and flight management system (FMS) parameters
• The FMC transmits navigation and tune data
• The MDC transmits display control data, and strapping data. All LRUs that transmit to the IOC transmit diagnostic words through the IOC to the MDC

The IOCs then transmit this data to the applicable LRUs. All data bus outputs from the IOCs are applied through the protection circuit to the applicable units and systems. The IOCs output data busses supply the applicable data words to the units that follow:

• Adaptive Flight Display Unit
• Air Data Computer (ADC)
• APU Electronic Control Unit (ECU)
• Brake Control Unit
• Control Display Unit (CDU)
• Data Concentration Unit (DCU)
• Flap Control Unit (FCU)
• Flight Guidance Computer (FGC)
• Flight Management Computer (FMC)
• Fuel Quantity Computer (FQC)
• Full Authority Digital Engine control (FADEC) System
• Global Positioning System (GPS)
• Horizontal Stabilizer Trim Electronic Control Unit (HST ECU)
• Lightning Detection System
• Maintenance Diagnostic Computer (MDC)
• Proximity Sensor Electronic Unit (PSEU)
• Radio Interface Unit (RIU)
• Spoiler Electronic Control Unit (SECU)
• Stall Protection Computer
• Weather Radar Receiver/Transmitter and Antenna

Power Supply

The PWR transmits PWR VALID and PWR SHUTDOWN WARN signals to the other IAPS LRUs to start and stop PWR operation. The PWR SHUTDOWN WARN shows that the PWR can only make sure there will be controlled voltage for a minimum of approximately 300 sec. The FGC, the FMC, and the IOC use PWR SHUTDOWN WARN. This gives them the time to put data into memory. After the PWR operates correctly again, the PWR lets the FGC, FMC, and IOC start again.

There are five green light emitting diodes (LEDs) that monitor the PWR. They are on during usual PWR operation. The applicable LEDs extinguish when there is a fault with one of the parameters.

The PWR automatically stops to operate in four minutes or less when the IAPS operates above 110 °C. The PWR starts to operate again only when the PWR internal temperature is less than 90 °C, and the primary power source has been stopped and started again.

Temperature Monitoring

The IEC is in the IAPS card cage. It monitors the temperature in the two halves of the ICC. Normal temperature range is -40 to 70 °C (-40 to 158 °F). When the IAPS temperature is between -40 °C and 23 °C, the fan is off. If either temperature transducer reaches 23 °C (73 °F), then the IEC turns on the cooling fan.

 The IEC receives analog temperature signals from transducers mounted in the No. 1 and No. 2 sides of the ICC. External temperature transducers are energized by the IEC. The IEC operates the same for the two temperature transducers.

There are four LEDs that monitor the IEC. Only three LEDs are used to monitor the IEC (HTR OVER TEMP is not used). They are extinguished during usual operation and they come on when there is a fault.

Configuration Strapping

The No. 1 IOC reads system configuration data from the No. 1 CSU. The No. 2 IOC reads system configuration data from the No. 2 CSU. The CSU has switches which can be set to open or to close to set the CSU parameters. There are 16 different strapping words and an 8-bit strapping word for the flight guidance system.

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The IOC monitors for fault conditions of the IAPS components. The fault condition signals are sent to the DCU and will give EICAS messages. The L (R) IAPS FAIL caution message will show when the data sent from the IOC to the DCU is invalid or when the PWR stops to operate.

The IAPS FAN FAULT advisory message will show when the IEC detects the PWR temperature is >110 °C (230 °F).

The EICAS messages that follow are related to the IAPS: 

EICAS MESSAGE(S)	LEVEL (COLOR)
L IAPS FAIL	CAUTION (amber)
R IAPS FAIL	CAUTION (amber)
IAPS FAN FAULT	ADVISORY (cyan)

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Component Location Index
IDENT	DESCRIPTION	LOCATION	IPC REF
A4	INTEGRATED-AVIONICS PROCESSOR SYSTEM (IAPS) CARD CAGE (ICC)	ZONE(S) 222	31-45-01
A4	INPUT/OUTPUT CONCENTRATOR UNIT (IOC) NO. 1	ZONE(S) 222	31-45-05
A4	INPUT/OUTPUT CONCENTRATOR UNIT (IOC) NO. 2	ZONE(S) 222	31-45-05
A4	INTEGRATED-AVIONICS PROCESSOR SYSTEM (IAPS) POWER SUPPLY (PWR) NO. 1	ZONE(S) 222	31-45-09
A4	INTEGRATED-AVIONICS PROCESSOR SYSTEM (IAPS) POWER SUPPLY (PWR) NO. 2	ZONE(S) 222	31-45-09
A4	INTEGRATED-AVIONICS PROCESSOR SYSTEM (IAPS) ENVIRONMENTAL CONTROLLER (IEC)	ZONE(S) 222	31-45-13
A4	CONFIGURATION STRAPPING UNIT (CSU) NO. 1	ZONE(S) 222	31-45-17
A4	CONFIGURATION STRAPPING UNIT (CSU) NO. 2	ZONE(S) 222	31-45-17
-	OPTIONS CONTROL MODULE (OCM) NO. 1	ZONE(S) 222	31-45-21
-	OPTIONS CONTROL MODULE (OCM) NO. 2	ZONE(S) 222	31-45-21

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