DOC AIRBUS | AMM A320FSTANDBY DATA : INTEGRATED STANDBY INSTRUMENT SYSTEM (ISIS) - DESCRIPTION AND OPERATION
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
** ON A/C NOT FOR ALL
1. General
A. ISIS Indicator
The Integrated Standby Instrument System (ISIS) indicator replaces the three conventional standby instruments:
The Integrated Standby Instrument System (ISIS) indicator replaces the three conventional standby instruments:
- the standby altimeter
- the standby horizon indicator
- the standby airspeed indicator.
B. Standby Compass
The standby heading is given by a magnetic compass that is an independent instrument which provides the flight crew with the A/C magnetic heading.
It is installed on the top of the windshield center post and allows a check of the heading provided by the main sources of the heading system. It acts in standby when these systems are inoperative.
The standby heading is given by a magnetic compass that is an independent instrument which provides the flight crew with the A/C magnetic heading.
It is installed on the top of the windshield center post and allows a check of the heading provided by the main sources of the heading system. It acts in standby when these systems are inoperative.
2. Component Location
** ON A/C NOT FOR ALL 
ISIS - Component Location| FIN | FUNCTIONAL DESIGNATION | PANEL | ZONE | ACCESS DOOR | ATA REF |
|---|---|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||||
| 2FN | COMPASS-STANDBY | 210 | 34-22-23 | ||
| 22FN | IND-ISIS | 401VU | 211 | 34-22-25 | |
3. System Description
A. ISIS Indicator - Initialization function
This function corresponds to the initialization phase of the ISIS indicator.
As soon as the ISIS indicator is energized, the display shows these four yellow digital boxes for approximately 90 s:
This function corresponds to the initialization phase of the ISIS indicator.
As soon as the ISIS indicator is energized, the display shows these four yellow digital boxes for approximately 90 s:
- ATT for the standby horizon function
- SPD for the airspeed indicator function, ALT for the altimeter function the standby horizon
- INIT 90 S for the initialization function.
ISIS performs an excessive motion test during the whole initialization phase.
If aircraft motion is detected, the attitude information is flagged and a yellow "ATT:RST" flag with a red ATT flag are displayed at the end of the initialization phase
Pressing the RST pushbutton switch more than 2 seconds then restarts the initialization phase.
The display also shows the baro reference. Baro reference can be set during the initialization phase.
B. ISIS Indicator - Standby airspeed indicator function
The standby airspeed indicator function measures the pitot/static pressure differential from the standby air data system and provides airspeed indication in knots.
The airspeed indication is displayed by means of a white tape positioned vertically in the left part of the display area.
The airspeed scale is linear with five-knot graduations from 5 to 250 kts, ten-knot graduations from 250 to 520 kts and digital values every 20 kts.
This tape moves up and down to indicate the A/C actual speed value in front of a fixed yellow reference line.
When the airspeed data is not valid, a red SPD flag is displayed in place of the airspeed scale.
The standby airspeed indicator function measures the pitot/static pressure differential from the standby air data system and provides airspeed indication in knots.
The airspeed indication is displayed by means of a white tape positioned vertically in the left part of the display area.
The airspeed scale is linear with five-knot graduations from 5 to 250 kts, ten-knot graduations from 250 to 520 kts and digital values every 20 kts.
This tape moves up and down to indicate the A/C actual speed value in front of a fixed yellow reference line.
When the airspeed data is not valid, a red SPD flag is displayed in place of the airspeed scale.
(1) Mach number
The Mach number is always computed.
When the Mach number is above .5 (increasing sense) it is displayed in green in the left bottom part of the display area, just below the speed scale in green color. The display range is .50 to .99 (increasing sense) and .99 to .45 (decreasing sense).
In case of failure, a red M flag is displayed in place of the Mach number.
The Mach number is always computed.
When the Mach number is above .5 (increasing sense) it is displayed in green in the left bottom part of the display area, just below the speed scale in green color. The display range is .50 to .99 (increasing sense) and .99 to .45 (decreasing sense).
In case of failure, a red M flag is displayed in place of the Mach number.
C. ISIS Indicator - Standby altimeter function
The standby altimeter indication is supplied with static pressure by the standby air data system to indicate the barometric altitude of the aircraft in feet.
The barometric altitude indication is displayed by means of a black tape with white indications, positioned vertically in the right part of the display area.
The altitude scale is linear from - 2000 to + 50,000 ft with 100 ft graduations, with digital indications every 500 ft.
This tape moves up and down with respect to a window surrounded in yellow within which the A/C actual altitude value is displayed in green digits.
The window is surrounded in cyan when an altitude bug is hidden by this read-out.
In this window, the hundreds of feet are written in a large size whereas the tens and units are displayed by a drum operating as a conventional mechanical altimeter.
When the altitude data is not valid, a red ALT flag is displayed in place of the altitude tape, but the selected pressure is always displayed.
The standby altimeter indication is supplied with static pressure by the standby air data system to indicate the barometric altitude of the aircraft in feet.
The barometric altitude indication is displayed by means of a black tape with white indications, positioned vertically in the right part of the display area.
The altitude scale is linear from - 2000 to + 50,000 ft with 100 ft graduations, with digital indications every 500 ft.
This tape moves up and down with respect to a window surrounded in yellow within which the A/C actual altitude value is displayed in green digits.
The window is surrounded in cyan when an altitude bug is hidden by this read-out.
In this window, the hundreds of feet are written in a large size whereas the tens and units are displayed by a drum operating as a conventional mechanical altimeter.
When the altitude data is not valid, a red ALT flag is displayed in place of the altitude tape, but the selected pressure is always displayed.
(1) Negative altitude
If the altitude is negative, the NEG indication is displayed in white close to the digital read-out. The range is - 2000 to 0 ft.
If the altitude is negative, the NEG indication is displayed in white close to the digital read-out. The range is - 2000 to 0 ft.
(2) Optional metric altimeter function
The metric altitude can be displayed in the right top part of the display in addition to the altitude in feet.
The metric altitude indication is displayed in green by means of a digital read-out surrounded in yellow. The cyan letter M is written just after the altitude value. The altitude in meters is rounded to the closest 10th of meters.
In case of negative altitude, the NEG indication is displayed in white just before the metric altitude value.
The metric altitude can be displayed in the right top part of the display in addition to the altitude in feet.
The metric altitude indication is displayed in green by means of a digital read-out surrounded in yellow. The cyan letter M is written just after the altitude value. The altitude in meters is rounded to the closest 10th of meters.
In case of negative altitude, the NEG indication is displayed in white just before the metric altitude value.
D. ISIS Indicator - Reference barometric pressure indication
By pushing the barometric reference (BARO) selector knob located in the right bottom corner of the indicator, the pilot can select the standard barometric pressure 1013.25 hPa (29.9212 in.Hg) or the barometric correction whose value (without units) can be adjusted by turning the knob (first press: STD, second press: baro correction).
The barometric correction is displayed in cyan, in the center bottom part of the display, in the range from 745 to 1100 hPa, with a variation of 10 hPa per rotation of the knob.
In case of standard barometric pressure selection, a cyan STD flag is displayed in place of the barometric correction value.
By pushing the barometric reference (BARO) selector knob located in the right bottom corner of the indicator, the pilot can select the standard barometric pressure 1013.25 hPa (29.9212 in.Hg) or the barometric correction whose value (without units) can be adjusted by turning the knob (first press: STD, second press: baro correction).
The barometric correction is displayed in cyan, in the center bottom part of the display, in the range from 745 to 1100 hPa, with a variation of 10 hPa per rotation of the knob.
In case of standard barometric pressure selection, a cyan STD flag is displayed in place of the barometric correction value.
(1) Optional barometric correction indication in inches of mercury (in.Hg)
The barometric correction value in in.Hg can be displayed (without the "in.Hg" mention), in cyan color, in the center bottom part of the display area, in addition to the barometric correction value in hPa.
In this case, the BARO selector knob enables the display of the reference barometric correction in the range from 22 to 32.48 in.Hg, with a variation of 0.01 in.Hg per rotation of the knob.
The barometric correction value in in.Hg can be displayed (without the "in.Hg" mention), in cyan color, in the center bottom part of the display area, in addition to the barometric correction value in hPa.
In this case, the BARO selector knob enables the display of the reference barometric correction in the range from 22 to 32.48 in.Hg, with a variation of 0.01 in.Hg per rotation of the knob.
E. ISIS Indicator - Standby horizon function
(1) Aircraft symbol
The fixed symbol is in yellow color, it comprises three parts: two simplified wing/landing gear parts plus a center part.
It provides the pilot with a quick glance attitude information, both in pitch and roll with respect to the attitude sphere.
The fixed symbol is in yellow color, it comprises three parts: two simplified wing/landing gear parts plus a center part.
It provides the pilot with a quick glance attitude information, both in pitch and roll with respect to the attitude sphere.
(2) Pitch angle information
The A/C present pitch angle is given by the vertical displacements of the pitch attitude scale with respect to the center of the A/C symbol. The scale moves behind the cut-sphere shaped window, limited by the lines of an upper (blue) and a lower (brown) sector. The scale rotates around the center of the A/C symbol in accordance with the A/C present roll angle.
The pitch scale comprises white reference lines and associated pitch angle values. The lines are given every 2.5 degrees from - 30 to + 30 degrees. Beyond 30 degrees, red large arrow heads (V-shaped) indicate an excessive attitude and the direction to follow in order to reduce it.
The A/C present pitch angle is given by the vertical displacements of the pitch attitude scale with respect to the center of the A/C symbol. The scale moves behind the cut-sphere shaped window, limited by the lines of an upper (blue) and a lower (brown) sector. The scale rotates around the center of the A/C symbol in accordance with the A/C present roll angle.
The pitch scale comprises white reference lines and associated pitch angle values. The lines are given every 2.5 degrees from - 30 to + 30 degrees. Beyond 30 degrees, red large arrow heads (V-shaped) indicate an excessive attitude and the direction to follow in order to reduce it.
(3) Roll angle information
A yellow triangle which remains on the line going through the center of the A/C symbol and which is perpendicular to the horizon line, moves against the fixed roll scale on the upper contour of the attitude sphere.
This fixed roll scale comprises white marks for the 10 degrees, 20 degrees, 30 degrees, 45 degrees and 60 degrees significant values, on either side of the zero position (horizontal wings) which is indicated by a small fixed black triangle surrounded in white.
A yellow triangle which remains on the line going through the center of the A/C symbol and which is perpendicular to the horizon line, moves against the fixed roll scale on the upper contour of the attitude sphere.
This fixed roll scale comprises white marks for the 10 degrees, 20 degrees, 30 degrees, 45 degrees and 60 degrees significant values, on either side of the zero position (horizontal wings) which is indicated by a small fixed black triangle surrounded in white.
(4) Attitude failure presentation
In case of detected failure of the pitch and/or roll angle information, the whole attitude and guidance display is replaced by the ATT red flag.
In case of detected failure of the pitch and/or roll angle information, the whole attitude and guidance display is replaced by the ATT red flag.
(5) Lateral acceleration
A black surrounded white trapezoidal index below the roll reference triangle represents the A/C lateral acceleration. Lateral acceleration is displayed in the range from -0,2 to +0,2g. If the lateral acceleration exceeds this range, it is not displayed any more. When the lateral acceleration is null, the centre of the symbol is in a neutral zone, the width of which corresponds to the middle of the base of the reference triangle. This can result on ISIS in a shifting up to one millimeter between this triangle and the symbol of lateral acceleration. This behaviour comes from a compromise between the resolution of the sensors, the precision of the display and the mounting of the equipment on the instrument panel.
A black surrounded white trapezoidal index below the roll reference triangle represents the A/C lateral acceleration. Lateral acceleration is displayed in the range from -0,2 to +0,2g. If the lateral acceleration exceeds this range, it is not displayed any more. When the lateral acceleration is null, the centre of the symbol is in a neutral zone, the width of which corresponds to the middle of the base of the reference triangle. This can result on ISIS in a shifting up to one millimeter between this triangle and the symbol of lateral acceleration. This behaviour comes from a compromise between the resolution of the sensors, the precision of the display and the mounting of the equipment on the instrument panel.
F. ISIS Indicator - LS function
When the LS pushbutton switch located on the right top part of the indicator is pushed, the Glide Slope (G/S) and Localizer (LOC) scales come into view.
If the LOC and/or G/S signals are in Failure Warning condition or No Refresh, the relative scale disappears and the relative red flag LOC and/or G/S appears respectively in the left bottom corner and/or in the right top corner of the display area. If the LOC and/or G/S signals are in NCD condition, only the scales without diamond are displayed.
When the LS pushbutton switch located on the right top part of the indicator is pushed, the Glide Slope (G/S) and Localizer (LOC) scales come into view.
If the LOC and/or G/S signals are in Failure Warning condition or No Refresh, the relative scale disappears and the relative red flag LOC and/or G/S appears respectively in the left bottom corner and/or in the right top corner of the display area. If the LOC and/or G/S signals are in NCD condition, only the scales without diamond are displayed.
G. Standby Compass
The standby compass consists of a magnetic element rotating inside a compass bowl, immersed in a damping liquid. The magnetic element (1) is linked to a graduated compass card which moves against a lubber line (2) and gives the magnetic heading.
Above the viewing window are two apertures (4) marked B (E.W) and C (N.S), allowing to achieve compensation by positioning the two small magnetized bars (compensator).
Below the viewing window is a non-magnetic lamp (3) assembly which provides illumination of the compass card.
The standby compass consists of a magnetic element rotating inside a compass bowl, immersed in a damping liquid. The magnetic element (1) is linked to a graduated compass card which moves against a lubber line (2) and gives the magnetic heading.
Above the viewing window are two apertures (4) marked B (E.W) and C (N.S), allowing to achieve compensation by positioning the two small magnetized bars (compensator).
Below the viewing window is a non-magnetic lamp (3) assembly which provides illumination of the compass card.
A. ISIS Indicator
The ISIS indicator is supplied with 28VDC from the essential busbar 401PP. In case of loss of this busbar, the supply of the ISIS indicator is automatically switched over to the battery busbar 703PP by means of the relay 7XB.
Consumption of the indicator is 20 W maximum in steady state.
Transparency time for the ISIS indicator is not less than 50 ms (memorizing of current configuration on power supply transients comprised between 50 and 200 ms).
The display is lost during power supply cut off comprised between 50 and 200 ms.
The system is supplied through these circuit breakers:
The ISIS indicator is supplied with 28VDC from the essential busbar 401PP. In case of loss of this busbar, the supply of the ISIS indicator is automatically switched over to the battery busbar 703PP by means of the relay 7XB.
Consumption of the indicator is 20 W maximum in steady state.
Transparency time for the ISIS indicator is not less than 50 ms (memorizing of current configuration on power supply transients comprised between 50 and 200 ms).
The display is lost during power supply cut off comprised between 50 and 200 ms.
The system is supplied through these circuit breakers:
| PANEL | DESIGNATION | FIN | LOCATION |
|---|---|---|---|
| ** ON A/C NOT FOR ALL | |||
| 49VU | NAV/STBY/INST | 5FN | F12 |
| 105VU | NAV/STBY/INST/BAT | 23FN | J01 |
5. Interface
A. Mechanical Interface
The ISIS indicator is to 3 ATI size in accordance with ARINC 408A.
The ISIS indicator is to 3 ATI size in accordance with ARINC 408A.
(1) Digital data inputs
The ISIS indicator receives digital data inputs from the following components:
The ISIS indicator receives digital data inputs from the following components:
(a) Inertial Reference
Two ARINC 429 high-speed buses provide the ISIS indicator with the optional magnetic heading indication (label 320).
In normal configuration, the parameters displayed on the ISIS indicator come from the ADIRU 1.
When a failure is detected, switching on the ADIRU 3 has to be performed manually through the ATT/HDG selector switch on the SWITCHING panel.
Two ARINC 429 high-speed buses provide the ISIS indicator with the optional magnetic heading indication (label 320).
In normal configuration, the parameters displayed on the ISIS indicator come from the ADIRU 1.
When a failure is detected, switching on the ADIRU 3 has to be performed manually through the ATT/HDG selector switch on the SWITCHING panel.
(b) ILS 1 (or MMR 1)
One ARINC 429 low-speed bus provides the ISIS indicator with the LS function (label 173 for LOC and label 174 for G/S).
One ARINC 429 low-speed bus provides the ISIS indicator with the LS function (label 173 for LOC and label 174 for G/S).
(c) A fourth ARINC 429 input (low or high speed) is reserved as system provision.
(2) Discrete Inputs
The ISIS indicator receives the following discrete inputs:
The ISIS indicator receives the following discrete inputs:
(a) Ground/open signal from the ATT/HDG selector switch for selection of active ADIRU 1 or 3.
(b) Ref baro pressure in in.Hg and hPa pin-program
- this discrete input permits the display of the reference barometric pressure in in.Hg in addition to the reference barometric pressure in hPa.
(c) Altitude in meter pin-program
- this discrete permits the display of the altitude value in meters in addition to the altitude value in feet.
(d) V-bars optional function pin-program
- this discrete permits to change the basic A/C symbol by the V-bars symbol.
(e) Test discrete input
- this discrete input allows the ISIS indicator to manage the BITE failures sent to the CFDIU.
(f) Four input discretes are used for indicator face tilting
The face of the ISIS indicator can be set at 0 deg. and tilted from 10 to 24 deg. by steps of 1 deg.
The face of the ISIS indicator can be set at 0 deg. and tilted from 10 to 24 deg. by steps of 1 deg.
(g) One discrete input is used as parity.
The parity control includes the monitoring of the optional function pin-programs and the ISIS indicator face tilt discretes. The parity discrete is activated only if the sum of the wired discretes is an even result.
The parity discrete is monitored during power-up tests and continuous built-in test. If the parity is valid, it is memorized into non volatile memory. If the parity is not valid, the last memorized configuration is used and the white MAINT flag is displayed in the left top part of the display area (when CAS < 50 kts) until the configuration is valid.
If the ATT 10s message appears when the MAINT flag is shown, the message has priority. The flag is displayed again as soon as the message disappears.
The parity control includes the monitoring of the optional function pin-programs and the ISIS indicator face tilt discretes. The parity discrete is activated only if the sum of the wired discretes is an even result.
The parity discrete is monitored during power-up tests and continuous built-in test. If the parity is valid, it is memorized into non volatile memory. If the parity is not valid, the last memorized configuration is used and the white MAINT flag is displayed in the left top part of the display area (when CAS < 50 kts) until the configuration is valid.
If the ATT 10s message appears when the MAINT flag is shown, the message has priority. The flag is displayed again as soon as the message disappears.
(3) Digital data output
The ISIS indicator provides the following outputs:
The ISIS indicator provides the following outputs:
(a) Centralised Fault Display Interface Unit (CFDIU)
The ISIS indicator is connected to the CFDIU to transmit the following words:
The ISIS indicator is connected to the CFDIU to transmit the following words:
- LRU identification, Part Number (P/N) and Serial Number (S/N) (label 354),
- Built-In Test (BITE) status (label 356),
- Unit code (label 377).
(b) ARINC 429 output bus (low speed) for the following air data:
- barometric corrected altitude in feet (label 204) and in meters if corresponding option is activated (label 214),
- standard altitude in feet (label 203) and in meters if corresponding option is activated (label 216),
- altitude rate (label 212),
- computed airspeed in knots (label 206),
- total pressure in hPa (label 242),
- uncorrected average static pressure in hPa (label 245),
- Mach number (label 205),
- barometric reference setting in hPa (label 234) and in in.Hg if corresponding option is activated (label 235).
(c) ARINC 429 output bus (high speed) for the following inertial data:
- body roll rate in degrees per second (label 327),
- roll angle in degrees (label 325),
- body pitch rate in degrees per second (label 326),
- pitch angle in degrees (label 324),
- body yaw rate in degrees (label 330),
- body longitudinal acceleration (label 331),
- body lateral acceleration (label 332).
(4) Discrete output
One discrete output is used for fault/healthy indication. This discrete is grounded when the indicator is out of order and when the OUT OF ORDER message is displayed.
One discrete output is used for fault/healthy indication. This discrete is grounded when the indicator is out of order and when the OUT OF ORDER message is displayed.
6. Component Description
A. External Description FIN: 22-FN
The face of the ISIS indicator has:
The face of the ISIS indicator has:
- an ATT/RST pushbutton switch to reset the horizon (attitude) function to the true value,
- two ( + and - ) brightness adjustment pushbutton switches,
- a BUGS pushbutton switch for the display/inhibition of the BUGS function,
- a LS pushbutton switch for the engagement/disengagement of the ILS function,
- a light sensor,
- a BARO rotary knob/pushbutton switch. The pushbutton switch is used to change the barometric pressure (which can be adjusted by the rotary knob) to the standard pressure and back again.
B. Internal Description FIN: 22-FN
The ISIS indicator contains the following subassemblies:
The ISIS indicator contains the following subassemblies:
- a Filtering Board (FIB)
- a Power Supply Unit (PSU)
- an Interface Board (INB)
- a Pressure Sensor Module (PSM)
- an Inertial Measurement Unit (IMU)
- a Control Processor and Graphic Display Module (CPGDM)
- an Optical Module (OPM).
(1) Filtering board
This board includes the rear plate with the two pressure unions for the static and the total pressures and the 41-pin external connector.
It ensures protection against electromagnetic interference and lightning strikes.
This board includes the rear plate with the two pressure unions for the static and the total pressures and the 41-pin external connector.
It ensures protection against electromagnetic interference and lightning strikes.
(2) Power supply unit
From the 28VDC, this unit supplies the voltages necessary for the operation of the indicator.
From the 28VDC, this unit supplies the voltages necessary for the operation of the indicator.
(3) Interface board
This board makes the interface between part of the indicator inputs/outputs, the pressure sensors, the inertial sensors, the face, the light box and the CPGDM.
It also supplies a clock signal at 20MHz.
This board makes the interface between part of the indicator inputs/outputs, the pressure sensors, the inertial sensors, the face, the light box and the CPGDM.
It also supplies a clock signal at 20MHz.
(4) Pressure sensor module
This module contains for each system (static pressure and total pressure):
This module contains for each system (static pressure and total pressure):
- a pressure sensor with a cell (silicon detector),
- a sensor memory with an electronic board that shapes the signals and stores the characterization parameters of the sensor.
(5) Inertial measurement unit
This unit includes three single-axis rate sensors (with analog outputs) and their temperature probes, two acceleration sensors and their temperature probes, and an electronic board.
Its functions are as follows:
This unit includes three single-axis rate sensors (with analog outputs) and their temperature probes, two acceleration sensors and their temperature probes, and an electronic board.
Its functions are as follows:
- angular rate measurement,
- temperature measurement,
- absolute acceleration measurement,
- storing of the IMU parameters (sensors, misalignment, identification),
- generation of configuration data (IMU presence, two or three accelerometers),
- generation of sensor healthy-operation discretes,
- digitization of the sensor data (analog-to-digital converter).
(6) Control processor and graphic display module
This module performs the computing and graphics generation functions.
The Control Processing Unit (CPU) part of the CPGDM processes the data received through the INB and directly from the IMU to calculate the operational parameters (altitude, attitude and airspeed).
The graphics part converts the data supplied by the CPU into smoothed symbology and drives the Liquid Crystal Display (LCD).
This module performs the computing and graphics generation functions.
The Control Processing Unit (CPU) part of the CPGDM processes the data received through the INB and directly from the IMU to calculate the operational parameters (altitude, attitude and airspeed).
The graphics part converts the data supplied by the CPU into smoothed symbology and drives the Liquid Crystal Display (LCD).
(7) Optical module
This module includes a LCD matrix, backlighting (light box with three tubes) and the control electronics for this lighting.
This module includes a LCD matrix, backlighting (light box with three tubes) and the control electronics for this lighting.
7. Operation
A. System Performance
The parameter computation frequency is sufficient to respect the required performances and to avoid important gap between two consecutive displayed values. The elapsed time between the acquisition of air data and the display of the parameters is less than 200 ms.
The parameter computation frequency is sufficient to respect the required performances and to avoid important gap between two consecutive displayed values. The elapsed time between the acquisition of air data and the display of the parameters is less than 200 ms.
(1) Standby airspeed indicator function
The ISIS indicator can operate from 0 to 600 kts without deterioration.
The ISIS indicator can operate from 0 to 600 kts without deterioration.
(2) Standby altimeter function
The ISIS indicator can operate from -2500 to 55,000 ft and at 40,000 ft/mn speed variation without deterioration.
The ISIS indicator can operate from -2500 to 55,000 ft and at 40,000 ft/mn speed variation without deterioration.
(3) Standby horizon function
The ISIS indicator can operate from -180 to +180 deg. in pitch and roll without deterioration.
The ISIS indicator can operate from -180 to +180 deg. in pitch and roll without deterioration.
- gyrometers (3): the indicator can follow a 100 deg./s pitch or roll variation, a 10,000 deg./square second angular acceleration. The associated monitoring is triggered when angular speeds becomes higher than 100 deg./s.
- accelerometers (2): the associated monitoring is triggered when the constant acceleration in x and/or y axis becomes greater than 2.5g.
If this monitoring is triggered, the "WAIT ATT" message is displayed
If the conditions become normal againand if the attitude performance remains adequate for 10 seconds, the "WAIT ATT" message disappears and is replaced by the horizon display.
Otherwise, after 10 seconds or if the attitude performance is affected, the attitude function is considered as failed and the "ATT:RST" message is displayed in place of the "WAIT ATT" message
Pressing the RST pushbutton switch more than 2 seconds in steady flight quickly resets the attitude information.
B. Control and Indicating
The face of the ISIS indicator includes the following controls:
The face of the ISIS indicator includes the following controls:
(1) BUGS pushbutton switch
When the BUGS pushbutton switch is pushed, the BUGS page is shown. This page is used to program characteristic speeds and altitudes displayed on speed and altitude scales respectively.
The BUGS page has two columns positioned vertically:
an SPD column made of four boxes and an ALT column made of two boxes.
Initially, the first box of the SPD column (left top) is flashing. The corresponding speed value has to be selected using the BARO selector knob (cyan SET/SELECT indication followed by an arrow in the right bottom part of the display). This value cannot be less than 30 kts and can only be selected or changed when "OFF" function is deselected (true also with altitude bugs). When the correct value is displayed, access to the next box (below) is made by pushing the "-" pushbutton switch. This box is then active and flashes. After the fourth box of the SPD column, access to the last box of the ALT column (right top) is made by using the BARO selector knob. The altitude values selected cannot be negative. The "-" pushbutton switch is also used to select the last ALT box and then the first SPD box again. The "+" pushbutton switch is used to return to the previous box.
The operational page is displayed again and the entered values are memorized by pushing the BUGS pushbutton switch or after 15 s without pilot action. These values are memorized until new values are entered, even in case of ISIS indicator power supply cutoff.
If one memorized bug has not to be displayed on speed or altitude scale, it is possible to hide it by pushing the BARO selector knob. The OFF indication is shown close to the selected box and the value is still displayed. By pushing the BARO selector knob again, the displayed and memorized bug is active. Initially, speed bugs are set to 30 and altitude bugs are set to 0. All the bugs can be hidden using the OFF function.
When the BUGS pushbutton switch is pushed, the BUGS page is shown. This page is used to program characteristic speeds and altitudes displayed on speed and altitude scales respectively.
The BUGS page has two columns positioned vertically:
an SPD column made of four boxes and an ALT column made of two boxes.
Initially, the first box of the SPD column (left top) is flashing. The corresponding speed value has to be selected using the BARO selector knob (cyan SET/SELECT indication followed by an arrow in the right bottom part of the display). This value cannot be less than 30 kts and can only be selected or changed when "OFF" function is deselected (true also with altitude bugs). When the correct value is displayed, access to the next box (below) is made by pushing the "-" pushbutton switch. This box is then active and flashes. After the fourth box of the SPD column, access to the last box of the ALT column (right top) is made by using the BARO selector knob. The altitude values selected cannot be negative. The "-" pushbutton switch is also used to select the last ALT box and then the first SPD box again. The "+" pushbutton switch is used to return to the previous box.
The operational page is displayed again and the entered values are memorized by pushing the BUGS pushbutton switch or after 15 s without pilot action. These values are memorized until new values are entered, even in case of ISIS indicator power supply cutoff.
If one memorized bug has not to be displayed on speed or altitude scale, it is possible to hide it by pushing the BARO selector knob. The OFF indication is shown close to the selected box and the value is still displayed. By pushing the BARO selector knob again, the displayed and memorized bug is active. Initially, speed bugs are set to 30 and altitude bugs are set to 0. All the bugs can be hidden using the OFF function.
(2) RST pushbutton switch
The RST (reset) pushbutton switch located in the left bottom part of the indicator enables to reset the attitude indication to the true value during stabilized flight (without pitch and roll angles and with stabilized speed).
During the reset, a yellow ATT 10s message is shown in the center of the display area, in place of the horizon line. After a 10-second delay, the operational page is automatically displayed.
The RST (reset) pushbutton switch located in the left bottom part of the indicator enables to reset the attitude indication to the true value during stabilized flight (without pitch and roll angles and with stabilized speed).
During the reset, a yellow ATT 10s message is shown in the center of the display area, in place of the horizon line. After a 10-second delay, the operational page is automatically displayed.
(3) LS pushbutton switch
This pushbutton switch located in the right top part of the indicator enables the display of the LS bars (LOC and G/S) (if the corresponding pin-program is activated) in place of the magnetic heading indications.
This pushbutton switch located in the right top part of the indicator enables the display of the LS bars (LOC and G/S) (if the corresponding pin-program is activated) in place of the magnetic heading indications.
(4) BARO selector knob
This grey barometric selector knob located in the right bottom corner of the indicator, enables to display the standard barometric pressure or the barometric correction whose value can be adjusted by turning the knob.
This knob is used for the selection of the altitude and airspeed bugs.
This grey barometric selector knob located in the right bottom corner of the indicator, enables to display the standard barometric pressure or the barometric correction whose value can be adjusted by turning the knob.
This knob is used for the selection of the altitude and airspeed bugs.
(5) Brightness control
The ISIS indicator has a manual and automatic display brightness control device, located on its face. The brightness ensures the readability in all environmental lighting conditions expected in service.
After a long power supply interrupt on ground (>200 ms), an average brightness value is selected. In other cases, the last memorized brightness value is selected.
The pushbutton switches are lighted for night vision in accordance with the general cockpit selection.
The ISIS indicator has a manual and automatic display brightness control device, located on its face. The brightness ensures the readability in all environmental lighting conditions expected in service.
After a long power supply interrupt on ground (>200 ms), an average brightness value is selected. In other cases, the last memorized brightness value is selected.
The pushbutton switches are lighted for night vision in accordance with the general cockpit selection.
8. Test
A. BITE Description
(1) General
The ISIS indicator is fitted with an internal flight/ground information in order to manage the BITE and to prevent maintenance mode activation in flight.
The test is inhibited when the internal computed airspeed is greater than 60 kts.
The ISIS indicator is fitted with an internal flight/ground information in order to manage the BITE and to prevent maintenance mode activation in flight.
The test is inhibited when the internal computed airspeed is greater than 60 kts.
NOTE: The ISIS indicator complies with ABD0018, ABD0048 and ABD0100 Specification.
The ISIS indicator is able to display maintenance data when the BUGS and the LS pushbutton switches are pushed simultaneously (at least 2 s). In this case, a menu with two items is shown on the Liquid Crystal Display (LCD). (a) OTHER DATA menu
When the key adjacent to the OTHER DATA item (-) is pushed, a specific menu made of two items (LRU IDENT and ENGINEERING DATA) is shown.
When the key adjacent to the OTHER DATA item (-) is pushed, a specific menu made of two items (LRU IDENT and ENGINEERING DATA) is shown.
- LRU IDENT item
Allows to display the P/N and the S/N of the ISIS indicator, the configuration of the equipment (optional functions activated) and the functional time counter. - ENGINEERING DATA item
The engineering data provides correlation parameters and snapshot data concerning the failure displayed.
In addition the engineering data enables to display the functional time counter.
(b) TESTS menu
When the key adjacent to the TESTS item (+) is pushed, a specific menu made of two items (FUNCTIONAL TEST (110s) and DISPLAY TEST) is shown.
When the key adjacent to the TESTS item (+) is pushed, a specific menu made of two items (FUNCTIONAL TEST (110s) and DISPLAY TEST) is shown.
- DISPLAY TEST item
The display test function enables to display white and black screens to check LCD screen state/quality. - FUNCTIONAL TEST (110s) item
When the key adjacent to the FUNCTIONAL TEST (110s) item (+) is pushed, the functional test is started and the message IN PROGRESS 110s is shown in the middle of the display area. At the end of the test, the message TEST OK is shown on the display area. In case of fault detection, the BITE displays a message.