DOC AIRBUS | AMM A320FAIR DATA, INERTIAL REFERENCE SYSTEM (ADIRU & CDU OR MSU) - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
The Air Data/Inertial Reference System (ADIRS) provides the main air data and heading/attitude/navigation data to the aircraft systems.
The main computers of the ADIRS are the three Air Data/Inertial Reference Units (ADIRU) which are controlled by the ADIRS Mode Selector Unit (MSU).
The ADIRS is a three channel system. Each channel is isolated from the others and provides independent information as defined in ARINC 738.
Each ADIRU contains:
** ON A/C NOT FOR ALL The Air Data/Inertial Reference System (ADIRS) provides the main air data and heading/attitude/navigation data to the aircraft systems.
The main computers of the ADIRS are the three Air Data/Inertial Reference Units (ADIRU) which are controlled by the ADIRS Mode Selector Unit (MSU).
The ADIRS is a three channel system. Each channel is isolated from the others and provides independent information as defined in ARINC 738.
Each ADIRU contains:
- An Air Data Reference (ADR) portion. Its operation is described in 34-13.
- An Inertial Reference (IR) portion. Its operation is described in 34-14.
The power supply is common for the ADR and IR portions and described in 34-11.
2. Component Location
The three ADIRUs are installed in the avionics compartment.
The ADIRS MSU is installed in the cockpit.
** ON A/C NOT FOR ALL The three ADIRUs are installed in the avionics compartment.
ADIRS - Component LocationThe ADIRS MSU is installed in the cockpit.
| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 1FP1 | ADIRU-1 | 127 | 34-12-34 | ||
| 1FP2 | ADIRU-2 | 128 | 34-12-34 | ||
| 1FP3 | ADIRU-3 | 120 | 34-12-34 | ||
3. Interface
A. Mechanical Interface
The ADIRUs are installed and aligned on a specific mounting tray in the avionics compartment in accordance with the installation design defined in ARINC 738. The ADIRU is to 4 MCU size. In order to ensure attitude and azimuth accuracy, the mounting tray orientation complies with the following tolerances:
The ADIRUs are installed and aligned on a specific mounting tray in the avionics compartment in accordance with the installation design defined in ARINC 738. The ADIRU is to 4 MCU size. In order to ensure attitude and azimuth accuracy, the mounting tray orientation complies with the following tolerances:
- pitch and roll: plus or minus 12 minutes
- azimuth: plus or minus 12 minutes.
B. Electrical Interface
(1) ADIRS MSU - General
The ADIRS MSU contains three identical connectors. Each connector is linked to one ADIRU by means of an insert position keying.
The four annunciator discretes ADR OFF, ADR FAULT, IR OFF and IR FAULT are linked to the ADIRS MSU from the ADIRU, through the annunciator light test and interface boards.
The ADIRS MSU contains three identical connectors. Each connector is linked to one ADIRU by means of an insert position keying.
The four annunciator discretes ADR OFF, ADR FAULT, IR OFF and IR FAULT are linked to the ADIRS MSU from the ADIRU, through the annunciator light test and interface boards.
(2) ADIRU - General
The ADIRU receives data and computes outputs in accordance with ARINC 738. It uses an ARINC 600 type 2 floating-connector.
The ADIRU receives data and computes outputs in accordance with ARINC 738. It uses an ARINC 600 type 2 floating-connector.
(3) ADIRU - Digital inputs
- Air Data Module (ADM) inputs
The ADR provides up to five ADM input buses. Only three of them are used to receive air mass data from remotely mounted ADM (Ref. 34-11), two linked to the static probe and one linked to the pitot probe.
NOTE: For the ADIRU 3, only two ADM input buses are used: one for the total pressure data and the other for the averaged static pressure data.
- digital baro-correction inputs
The ADR provides two baro-correction digital data input ports. The incoming data from the Flight Control Unit (FCU) is in ARINC 429 low-speed format.
The ADR receives data from baro-correction bus A.
The baro-correction is used to compensate baro-corrected altitude output. - initialization data inputs
The IR portion of the ADIRU receives data from either ARINC 702 Flight Management and Guidance Computer (FMGC). The data is in ARINC 429 low-speed format. The initialization parameters are latitude and longitude or magnetic heading. - CFDIU input
The ADIRU provides one Centralized Fault Display Interface Unit (CFDIU) input bus. The data is in ARINC 429 low-speed format.
The CFDIU continuously transmits data to all systems. The ADIRU uses this data to accept commands from the CFDIU. - Air Data Reference inputs
The IR portion of the ADIRU provides two digital data input ports for receiving data from the other ADIRUs.
The incoming data is in ARINC 429 low-speed format and includes altitude and true airspeed. - the ADIRU provides provision for digital input buses (two buses are reserved for the Global Positioning System (GPS)).
(4) ADIRU - Analog inputs
- analog AOA input
The ADR portion of the ADIRU accepts two resolver inputs of indicated angle of attack.
The characteristics of the resolvers, as seen by the ADR, are as follows:. scale factor: 1°/Degree of AOA . index reference: 0° resolver input = 25° AOA - Total Air Temperature (TAT) sensor
The ADR portion of the ADIRU accepts a standard 500 ohm platinum sensing element input from the TAT sensor.
The ADR derives the measured temperature from the TAT sensor input using the Callender-Van Dusen equation from ARINC 738. - GPS Time Mark inputs
This allows the ADIRU to be synchronized with the GPS portion of the MMRs. - 115 VAC
The ADIRU operates from the 115 VAC/400 Hz primary power. - 28 VDC back-up
The ADIRU can operate from the 28 VDC back-up power. - 26 VAC reference
The ADIRU accepts up to three 26 VAC resolver reference inputs. Only one is used for the AOA resolver.
(5) ADIRU - Discrete inputs
These inputs are generally pin programs except for:
These inputs are generally pin programs except for:
- Static Source Error Correction (SSEC) and AOA correction and selection discretes which come from the Slat and Flap Control Computers (SFCC) and are linked to flap position,
- heat discretes which come from the associated Probe Heat Computer (PHC),
- VMO/MMO discrete provided by the position of the L/G DOWN VMO/MMO SELECTION switch (22FP).
- ADR selection:
It indicates, to the IR, the air data source to be used. - ADR OFF, IR OFF:
It indicates, to the ADIRU, that the crew has pushed the ADR pushbutton switch on the ADIRS MSU. This commands the ADIRU to stop the transmission of the ADR output buses. - IR MODE SELECT:
It indicates, to the ADIRU, the position of the associated selector switch on the MSU. Three positions can be coded: OFF, NAV, ATT. This gives the computer operating mode.
(6) ADIRU - Pin program discrete functions
The functions of the pin program discretes are:
The functions of the pin program discretes are:
- aircraft identification:
seven discretes provide the ADIRU with the identification of the aircraft.
They are used by the ADR to select the appropriate SSEC and AOA correction laws and by the IR to select the appropriate filtering (bandwidth) of the output labels. - baro-correction source selection:
This discrete provides the ADIRU with the following:. the form (digital or analog) in which the baro-correction transmission is made.
. the number of sources (2 or 3). the type of transmission used by the digital sources (single bus or various buses).
On the A/C, the FCU transmits the CAPT and F/O baro-correction in digital form on separate buses. - AOA average/unique:
The ADIRU receives the AOA on two resolvers.
This discrete indicates whether the computation must use an average value from the two resolvers, or the value of resolver 1 in priority with the second as a back-up in case of failure. This last solution is chosen on the A/C. - ADR ARINC filter select:
This permits to choose between two sets of filter characteristics for the ADR outputs. - mounting position:
This indicates the orientation of the unit to the IR portion. It is used to know where are the longitudinal and lateral axes of the aircraft and the sign of motion measured. - SDI:
This indicates on which side (CAPT, F/O, Standby) the ADIRU is installed. - CFDS message select:
The ADIRU selects a table of maintenance messages. - GPS sensor present:
This indicates, to the ADIRU, the presence on-board the aircraft of one or two MMRs (GPS portion). - GPS priority select:
This indicates, to the ADIRU, the priority for using the MMRs (GPS portion). - IR Remote Test:
This input starts the IR functional test mode. - Enhanced Alignment:
The ADIRU uses this input to make a selection of a basic fixed time alignment or an enhanced variable time alignment. This discrete also lets the ADIRU use automatic GPS initialization. - Data Loader enable:
This discrete is used to establish the data loading status.
(7) ADIRU - Digital outputs
- The ADR portion of the ADIRU provides eight identical ARINC 429 Low-Speed buses. Two of these buses are dedicated to the interface with the Electronic Control Units (ECU).
The number of these buses is 5 and 6.
The system users are described in the table below:---------------------------------------------------------------------------- ! USERS ! ADR 1 BUS ! ADR 2 BUS ! ADR 3 BUS ! ! !-----------------!-----------------!-----------------! ! !1 !2 !3 !4 !5 !6 !1 !2 !3 !4 !5 !6 !1 !2 !3 !4 !5 !6 ! !--------------------------------------------------------------------------! !ADIRU 1 ! ! ! ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ADIRU 2 ! !* ! ! ! ! ! ! ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ADIRU 3 ! ! !* ! ! ! ! ! ! !* ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !FMGC 1 ! ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !FMGC 2 ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !DMC 1 !* ! ! ! ! ! ! !* ! ! ! ! ! ! !* ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !DMC 2 ! !* ! ! ! ! !* ! ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !DMC 3 ! ! !* ! ! ! ! ! !* ! ! ! !* ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ATC 1 ! ! ! !* ! ! ! ! ! ! ! ! ! ! ! !* ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ATC 2 ! ! ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !FWC 1 ! ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !FWC 2 ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !CFDIU ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ECU or EEC ENG 1 ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !PVIS (1) ! ! ! ! ! ! ! ! ! !* ! ! ! ! ! ! ! ! ! !Passenger Visual ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !Information ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !Landscape Camera (1)! ! ! ! ! ! ! ! ! !* ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !AINS (1)! ! ! ! ! ! ! ! ! !* ! ! ! ! ! ! ! ! ! !Aircraft Information! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !Network System ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ECU or EEC ENG 2 ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !SFCC 1 ! ! !* ! ! ! ! ! !* ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !SFCC 2 ! !* ! ! ! ! ! !* ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !FAC 1 ! ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !FAC 2 ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ELAC 1 ! ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ELAC 2 ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !SEC 1 ! ! !* ! ! ! ! ! ! ! ! ! ! ! !* ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !SEC 2 ! !* ! ! ! ! ! !* ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !SEC 3 ! ! ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !WR 1 (option PWS) ! ! !* ! ! ! ! ! ! ! ! ! ! ! !* ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !WR 2 (option PWS) ! ! ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !DMU (option) ! !* ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !AOA CAPT INDICATOR ! ! ! !* ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !(option) ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !AOA F/O INDICATOR ! ! ! ! ! ! ! ! ! !* ! ! ! ! ! ! ! ! ! !(option) ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !GPWC (option) ! ! ! !* ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !DMU (option) ! !* ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !CABIN PRESSURE ! ! !* ! ! ! ! ! ! !* ! ! ! ! !* ! ! ! ! !CONTROLLER1 ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !CABIN PRESSURE ! ! ! !* ! ! ! !* ! ! ! ! ! ! ! !* ! ! ! !CONTROLLER2 ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !ZONE TEMPERATURE ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !* ! ! ! !CONTROLLER ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !--------------------!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--!--! !TEST 1 CONNECTORS ! ! ! !* ! ! ! ! ! !* ! ! ! ! ! !* ! ! ! ---------------------------------------------------------------------------- Table 11: ADR Data Users
(8) ADIRU - IR portion - System users table
- The IR portion of the ADIRU provides four identical ARINC 429 High-Speed buses. The system users are described in the table below:
------------------------------------------------------------------------- ! USERS ! IR 1 BUS ! IR 2 BUS ! IR 3 BUS ! ! !-------------------!-------------------!-------------------! ! ! 1 ! 2 ! 3 ! 4 ! 1 ! 2 ! 3 ! 4 ! 1 ! 2 ! 3 ! 4 ! !-----------------------------------------------------------------------! !FAC 1 ! ! ! * ! ! ! ! * ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !FAC 2 ! ! * ! ! ! ! * ! ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !ELAC 1 ! ! ! * ! ! ! ! * ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !ELAC 2 ! ! * ! ! ! ! * ! ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !SEC 1 ! ! ! * ! ! ! ! ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !SEC 2 ! ! * ! ! ! ! * ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !SEC 3 ! ! ! ! ! ! * ! ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !DMC 1 ! * ! ! ! ! ! ! * ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !DMC 2 ! ! * ! ! ! ! * ! ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !DMC 3 ! ! ! * ! ! ! ! * ! ! * ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !FMGC 1 ! ! ! * ! ! ! ! * ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !FMGC 2 ! ! * ! ! ! ! * ! ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !FQIC ! ! * ! ! ! ! * ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !BSCU ! ! * ! ! ! ! ! * ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !CFDIU ! ! ! * ! ! ! ! * ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !GPWC (1)! ! ! * ! ! ! ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !WR 1 ! ! ! * ! ! ! ! ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !WR 2 (1)! ! ! ! ! ! * ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !TCAS ! ! ! * ! ! ! ! ! ! ! ! ! ! !/T2CAS(1) ! ! ! ! ! ! ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !DMU (1)! ! * ! ! ! ! ! * ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !GPS 1 (1)! ! * ! ! ! ! ! ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !GPS 2 (1)! ! ! ! ! * ! ! ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !MMR 1 (1)! ! * ! ! ! ! ! * ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !MMR 2 (1)! ! ! * ! ! ! * ! ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !RMI-VOR/DME! ! * ! ! ! ! ! ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !RMI-ADF (1)! ! ! * ! ! ! ! ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !TEST PLUG ! ! ! * ! ! ! * ! ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !ISIS ! ! * ! ! ! ! ! ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !MCDU 1 ! ! ! * ! ! ! ! ! ! ! ! * ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !MCDU 2 ! ! ! ! ! ! * ! ! ! ! * ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !ATC 1 ! ! * ! ! ! ! ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !ATC 2 ! ! ! ! ! ! * ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !PVIS (1)! ! ! ! ! ! ! * ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !SATCOM (1)! ! * ! ! ! ! * ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !HFDR 1 (1)! ! ! * ! ! ! ! ! ! ! ! ! ! !-----------!----!----!----!----!----!----!----!----!----!----!----!----! !HFDR 2 (1)! ! ! ! ! ! * ! ! ! ! ! ! ! ------------------------------------------------------------------------- (1) Optional system Table 12 : IR Data Users - Basic version
(9) ADIRU - Analog outputs
The ADIRUs, through analog outputs, supply the ADMs with +13.5/-13.5 VDC.
The ADIRUs, through analog outputs, supply the ADMs with +13.5/-13.5 VDC.
(10) ADIRU - Discrete outputs
The discrete outputs are either open/ground or open/28 VDC discretes (for ON BAT, IR FAILURE WARNING and ALIGN NOT READY discretes). The LOW SPEED WARNING discretes are set according to a speed threshold (with a hysteresis of 4 knots). These thresholds are respectively:
The LOW SPEED WARNING 1 discrete is used in the Ram Air Turbine extension logic and in the power generation logic. The LOW SPEED WARNING 2 discrete is used in the power generation logic.
The following discretes are used to control the MSU annunciators:
The discrete outputs are either open/ground or open/28 VDC discretes (for ON BAT, IR FAILURE WARNING and ALIGN NOT READY discretes). The LOW SPEED WARNING discretes are set according to a speed threshold (with a hysteresis of 4 knots). These thresholds are respectively:
| --------------------------------- |
| !Lower threshold!Upper threshold! |
| ! value ! value ! |
| --------------------------!---------------!---------------! |
| ! LOW SPEED WARNING 1 ! 100 ! 104 ! |
| ! LOW SPEED WARNING 2 ! 50 ! 54 ! |
| ! LOW SPEED WARNING 3 ! 155 ! 159 ! |
| ! LOW SPEED WARNING 4 ! 260 ! 264 ! |
| ----------------------------------------------------------- |
The LOW SPEED WARNING 1 discrete is used in the Ram Air Turbine extension logic and in the power generation logic. The LOW SPEED WARNING 2 discrete is used in the power generation logic.
The following discretes are used to control the MSU annunciators:
- ON BAT
- ADR OFF
- ADR FAILURE WARNING
- IR OFF
- IR FAILURE WARNING.
4. Component Description
A. ADIRS FIN: 2-FP
The MSU contains three identical connectors referenced J1, J2 and J3.
- ADIRS MSU
The MSU is a three-channel unit. Each MSU channel is dedicated to one separate ADIRU and includes the following features: - a three-position mode selector switch. The modes are:
. power off (OFF)
. navigation (NAV)
. reversionary attitude (ATT)
NOTE: The NAV position has a detent which requires a pull force to change from NAV to ATT or from NAV to OFF.
- a pushbutton switch to disable IR output buses. It is a momentary action pushbutton switch
- an indicator announcing when the IR output buses are turned off (OFF legend of the IR pushbutton switch)
- an IR fault indicator (FAULT legend of the IR annunciator)
- a pushbutton switch to disable ADR output buses. It is a momentary action pushbutton switch
- an indicator announcing when the ADR output buses are turned off (OFF legend of the ADR pushbutton switch)
- an ADR fault indicator (FAULT legend of the ADR pushbutton switch).
The MSU contains three identical connectors referenced J1, J2 and J3.
(1) General
The ADIRU is contained in a 4 MCU case as defined in ARINC 600. The ADIRU has to be aligned on a special shelf in the avionics compartment in accordance with the installation design described in ARINC 738. This installation involves modification of the ARINC 600 standard to include three alignment pins and a floating connector.
Pins 12 and 13 of the bottom plug have been modified with a reducer to accept power input instead of coax input as defined in ARINC 738.
All input discretes are electrically isolated by an in-line diode or an equivalent device. The discrete outputs are protected by means of diodes to permit a wired OR circuit with other outputs.
The ADIRU is designed to reach a high level of protection for lightning and Electromagnetic Interference (EMI). The lightning protection circuitry is made up of discrete components which consist of high-powered Zener diode type semiconductors called Transzorbs. Varistors are used on the power supply input lines. Varistors are voltage-controlled resistors that go to a low impedance state when a voltage above their clamp voltage is applied, thus shunting the lightning current.
The ADIRU Power Dissipation is less than 50W and the device is passively cooled. Device cooling is accomplished through conduction of heat from internal components and natural convection on the external surfaces. Additionally, a high-emissivity coating may be used on selective chassis surfaces to enhance the ability for heat to be transferred out of the device. In addition, low voltage logic is used to reduce internal power dissipation.
As each ADIRU is a common point to all engines installed on the aircraft, special care is taken to make impossible any electrical disturbance to propagate through the ADIRU/engine interface to other inputs/outputs dedicated to engines.
The ADIRU is supplied by power 115VAC and 28VDC. The ADIRU processes and outputs Global Positioning, Air Data and Inertial Reference data in a single unit built around an MPC8245 processor.
Five resolvers can be used for the analog baro-correction and the AOA inputs.The ADR part provides 8 ARINC A429 low speed output buses. A bus isolation is provided using in-line fuses in all ADR buses 5-8 reserved to the engine control. Each bus can drive 20 ARINC bus loads.
The IR part provides 4 ARINC 429 high speed output buses. Each bus can drive 20 loads.
The gyros/accel sensors block contains three accelerometers and three gyros mounted along each axis.
The ADIRU is contained in a 4 MCU case as defined in ARINC 600. The ADIRU has to be aligned on a special shelf in the avionics compartment in accordance with the installation design described in ARINC 738. This installation involves modification of the ARINC 600 standard to include three alignment pins and a floating connector.
Pins 12 and 13 of the bottom plug have been modified with a reducer to accept power input instead of coax input as defined in ARINC 738.
All input discretes are electrically isolated by an in-line diode or an equivalent device. The discrete outputs are protected by means of diodes to permit a wired OR circuit with other outputs.
The ADIRU is designed to reach a high level of protection for lightning and Electromagnetic Interference (EMI). The lightning protection circuitry is made up of discrete components which consist of high-powered Zener diode type semiconductors called Transzorbs. Varistors are used on the power supply input lines. Varistors are voltage-controlled resistors that go to a low impedance state when a voltage above their clamp voltage is applied, thus shunting the lightning current.
The ADIRU Power Dissipation is less than 50W and the device is passively cooled. Device cooling is accomplished through conduction of heat from internal components and natural convection on the external surfaces. Additionally, a high-emissivity coating may be used on selective chassis surfaces to enhance the ability for heat to be transferred out of the device. In addition, low voltage logic is used to reduce internal power dissipation.
As each ADIRU is a common point to all engines installed on the aircraft, special care is taken to make impossible any electrical disturbance to propagate through the ADIRU/engine interface to other inputs/outputs dedicated to engines.
The ADIRU is supplied by power 115VAC and 28VDC. The ADIRU processes and outputs Global Positioning, Air Data and Inertial Reference data in a single unit built around an MPC8245 processor.
Five resolvers can be used for the analog baro-correction and the AOA inputs.The ADR part provides 8 ARINC A429 low speed output buses. A bus isolation is provided using in-line fuses in all ADR buses 5-8 reserved to the engine control. Each bus can drive 20 ARINC bus loads.
The IR part provides 4 ARINC 429 high speed output buses. Each bus can drive 20 loads.
The gyros/accel sensors block contains three accelerometers and three gyros mounted along each axis.
(2) Dataloading Capabilities
The ADIRU provides on-board dataloading capabilities. This capability allows an operator to perform software updates without removing the ADIRU from aircraft. Dataloading operations are accessible through a Portable Data Loader (PDL) plugged on dedicated connectors located at the bottom of the panel 80VU.
The ADIRU software is split into 3 parts:
As the operational software and the 2 Data tables can be dataloaded in the ADIRU, only the hardware P/N is available on the LRU identification plate. The software P/Ns are accessible through aircraft means (BITE interactive mode, Multi-Purpose Control and Display Unit (MCDU)). When the ADIRU is powered, the identification of the complete configuration is available through a Standalone Identification System (SIS) reader connector located on its front face.
The ADIRU provides on-board dataloading capabilities. This capability allows an operator to perform software updates without removing the ADIRU from aircraft. Dataloading operations are accessible through a Portable Data Loader (PDL) plugged on dedicated connectors located at the bottom of the panel 80VU.
The ADIRU software is split into 3 parts:
- The Operational Software (OPS) implements all the ADIRU functions (inertials, air data, GPS, maintenance...).
- One table of operational constants (Data table 1) provides the aircraft dependent data. These data correspond to the different aircraft correction laws (Static Source Error Correction, anemometric and clinometric laws, temperature correction laws) and to the values of several monitoring thresholds. These data are used in the ADR calculations of the ADIRU.
- Another table of operational constants (Data table 2) provides the magnetic deviation coefficients that are used to compute the magnetic-referenced parameters from the true-referenced parameters. These coefficients are based on the National Oceanic and Atmospheric Association (NOAA) publications that are updated every five years. These data are used in the IR calculations of the ADIRU.
As the operational software and the 2 Data tables can be dataloaded in the ADIRU, only the hardware P/N is available on the LRU identification plate. The software P/Ns are accessible through aircraft means (BITE interactive mode, Multi-Purpose Control and Display Unit (MCDU)). When the ADIRU is powered, the identification of the complete configuration is available through a Standalone Identification System (SIS) reader connector located on its front face.