05/10/16
Overview
The purpose of the standby instrument system is to provide the flight crew with an independent source of heading, attitude, altitude and airspeed required to meet the safety requirements. These stand-alone instruments provide the necessary minimum flight environment information in the event of a serious system failure.
The standby airspeed/altimeter system supplies the flight crew with backup display of barometric altitude and airspeed indications.
05/10/16
Standby Altimeter/Airspeed Indicator
The standby ALT/ASI is installed in pre-9158 aircraft and is mounted on the center instrument panel. The standby altimeter/airspeed indicator contains two independent, barometric-driven mechanisms.
Altitude is displayed over the range of –1,000 to +50,000 ft in 100 ft increments. The altitude pointer and counter operate through a mechanical linkage to a pressure capsule. Static pressure variations cause the capsule to contract or expand which causes the altitude indication to change. The counter has two drums for the indications. One drum shows the tens of thousands feet indication, and one drum has a fixed 000 display and shows the thousand feet indication. Each complete turn of the pointer shows a 1,000 foot increase or decrease in altitude on the counter. The warning flag comes into view when the altitude falls below 10,000 feet. The altitude display is corrected for changes in prevailing pressure setting, rotating the baro selector knob on the bezel. The baro selection is displayed in both inches of mercury (inHg) and millibars/ hectopascals (mb/hPa). The static source to the altimeter is from the standby pitot-static and P1 probes.
Airspeed is displayed in knots on a drum rotating against a fixed index on the dial. Drum markings are open at the lower end of the scale where readability is more important and is gradually compressed towards the high range. Airspeed is displayed over the range of 60 to 450 knots.
05/10/16
Integrated Electronic Standby Instrument
On aircraft serial numbers 9158 and subsequent numbers, the system consists of a standby compass and an integrated electronic standby instrument (IESI).
The IESI is a self-contained unit installed on the instrument panel between the EICAS monitors. The IESI displays artificial horizon, altimeter and airspeed information on a liquid crystal display screen.
The IESI is a display instrument and it comprises the following:
- An active matrix liquid crystal flat panel screen
- Four push-buttons providing for:
- Caging the virtual platform "CAGE"
- Resetting the baro pressure to the standard value (1,013.25 hPa or 29.92 in Hg) "STD"
- Adjusting the brightness of the display "+"
- Adjusting the brightness of the display "−"
- A rotary knob (to adjust barometric correction)
- Inertial sensors and pressure sensors
The equipment is intended to provide "standby" display for the following parameters:
- Attitude
- Metric altitude digital readout
- Standard or baro-corrected altitude and the associated barometric pressure
- Airspeed
Optional Functions Pin Programming allows for the display of the following parameters:
- Heading (not selected)
- Barometric pressure in hPa and / or in Hg (selected for both hPa and in Hg)
- ILS localizer and Glideslope deviation (selected)
Aircraft Configuration Pin Programming allows for the adaptation of the following functions:
- Static Source Error Correction (SSEC) laws
- VMO laws
- Panel Tilt Angle required compensation (18 degrees)
INTEGRATED ELECTRONIC STANDBY INSTRUMENT
STANDBY ARTIFICAL HORIZON CB/RELAY PANEL (FOR IESI)
05/10/16
System Operation
Standby Airspeed/Altimeter Indicator
The ALT/ASI uses a conventional 3 ATI case with a circular window on the front of the unit. The standby ALT/ASI is connected to the standby pitot/static port of the aircraft.
Airspeed is displayed, in knots, on a drum rotating against a fixed index on the dial. Drum markings are open at the lower end of the scale where readability is more important and gradually compressed towards the top of the range. Airspeed is displayed over the range of 60 to 450 knots.
The standby ALT/ASI consists of two independent barometric-driven mechanisms, one for altitude and the other for airspeed, housed in a single sealed case. Altitude information is presented by means of an altitude pointer reading against a circular graduated dial and a height counter.
Barometric pressure is displayed by two counters to either side of the altimeter pointer. One display is in millibars/hectopascals (mb/hPa), and the other is displayed in inches of mercury (Hg).
The altitude counter consists of a 1,000 feet per revolution pointer and a five-digit counter. The counter has three fixed zeros and is mechanized such that a 1,000 feet per increment drum is indexed by the pointer shaft and therefore executes a complete change of numeral for each 1,000 feet ofaltitude. The 10,000 feet per increment drum is further indexed by the 1,000 feet per increment drum and therefore executes a complete change of numeral for each 10,000 feet of altitude.
The bold horizontal line serves to separate the airspeed and altitude elements of the display. Indicated airspeed (IAS) is displayed by means of a graduated airspeed drum, reading against a fixed lubber line.
An integral oscillator, energized by 28 VDC from the aircraft essential bus, operates a vibrator to reduce the effect of friction in the altitude mechanism. The presentation is integrally lit by 5 VDC incandescent bulbs.
The barometric pressure set knob adjusts the position of the mb/hPa counter and inches of Hg counter and simultaneously corrects the altitude pointer reading. The set knob is located in the lower left-hand corner of the unit face. The datum adjustment screw provides for adjustment of zero reading at sea level when the correct barometric pressure is set.
The standby ALT/ASI is capable of displaying the following ranges:
- Altimeter range −1,000 feet to +50,000 feet
- Airspeed range 60 to 450 knots
- Baroset 22.00 to 30.99 in Hg 745 mb/hPa to 1,049.4 mb/hPa
Integrated Electronic Standby Instrument
The IESI software is programmed with Discrete INPUTS. The pin programmable inputs are for the installation configuration of the IESI, A/C configuration data and formulas. This is related to tilt-angles, misalignments and mathematical equations for SSEC and VMO/MMO laws. Also, the software includes the optional air data. Access to the optional data is not available and it is not necessary for the usual operation of the IESI.
The power-up or the initialization mode is completed after approximately 1.5 minutes. At the start of the power-up the white “ALIGNING” annunciation shows at the center of the IESI display. At the same time, the initialization mode includes a power-up built-in test (P-BIT) sequence.
The P-BIT examines the IESI for faults before the IESI can operate. If there is a fault, an applicable warning message will be shown on the IESI display. When the align sequence is completed the IESI display shows the IAS and altitude tape-scales with the pitch/roll attitude. The IESI attitude must be equal ±1 degree to the PFD attitude. Subsequently, at regular intervals, the IESI receives and calculates the data shown.
The Pressure Measurement Unit (PMU), installed in the IESI, receives the pitot and static pressures to calculate the altitude and the IAS. Two solid-state pressure transducers, installed in the PMU, receive the pitot and static air pressures and change the pressures into frequency identified signals. The signals get measured by installed precision meters. The meters change the signal input into discrete output signals and send the signals to the IESI processor.
The processor calculates the signals as the IAS and the baro-corrected altitude. The altitude data gets sent along two ARINC 429 output data-buses to the IESI display. The IAS data gets sent along two ARINC 429 output LS data-buses to the IESI display.
Static source errors (SSE) get transmitted into the static pressure system. These errors occur when air flow around the static probe inlet is not stable. The SSE change with speed, altitude and angle of attack. To adjust for SSE and to calculate altitude and IAS, the PMU uses a static-source error correction (SSEC) function. This function calculates modelization coefficients, pressure, airspeed, altitude and Mach number data.
Each A/C has a unique SSEC function. Its value is a function of given parameters. If the SSEC function can not calculate, the IESI will show the amber SSEC flag on the display.
The altitude shows on a vertical moving tape-scale. The scale shows 100 ft graduations and 500 ft numerical marks. The IAS value with 20 ft resolutions shows in a center box of the scale. Altitudes of −2,000 to +55,000 feet can show on the IESI display. Altitude in meters shows in a 5 digit box at the top right of the tape-scale. Altitude in meters is enabled or disabled by the selection of METRIC ALT on the MFD MENU.
The IAS shows on a vertical moving tape-scale, against a numerical speed drum, in a 3-digit box that does not move. The box contains a counter that shows the IAS with 1 kt resolutions. The IAS has 20 kt increments between the top and the bottom tape-scale values. The tape-scale has 5 kt graduations between airspeeds of 30 and 250 kts and 10 kt graduations when speeds are more than 250 kts.
When airspeed values are higher than VMO, the values show in red-tape in the top left tape-scale. The VMO value is calculated by the VMO law and the indicated altitude. When the IAS increases and becomes higher than VMO, plus the offset value, the speed drum turns green on a black background. Then if the IAS increases more and is higher than VMO, plus the offset value, the speed drum turns white on a red background. The IAS operates and shows airspeeds between 30 to 520 kts.
The Mach number shows in the lower left of the IESI display, below the airspeed tape-scale. The Mach number shows when the value is ≥ 0.45. The Mach number is calculated by the SSEC law and Ps/Pt is necessary to help the SSEC law calculate. When the IAS increases and becomes higher than VMO, plus the offset value, the Mach number turns green on a black background. If the IAS increases more and is higher than VMO, plus the offset value, the Mach number turns white on a red background.
The Inertial Measurement Unit (IMU), installed in the IESI, calculates the pitch and roll angles (attitude). To calculate attitude, the IMU measures tilt-angles (A/C rotation speed and acceleration) and IMU misalignment inputs. To calculate the inputs, the IMU uses three rate gyro sensors, two accelerometers and their related temperature sensors. The IESI changes the inputs into digital format and sends the format to the IESI processor.
The processor calculates the format and sends it to the IESI display. The display shows the aircraft attitude on a two-color or sky-earth tape (blue and brown). A white horizon line divides the two colors.
Lateral acceleration (Slip/Skid) is calculated from the input of the IMU. Slip/Skid occurs when a left or a right lateral acceleration occurs. A Slip/Skid shows on the IESI display when the trapezoidal indicator, relative to the roll triangle sky-pointer, moves left or right.
05/10/16
Control and Display
Integrated Electronic Standby Instrument
The IESI controls are operated by the flight crew with four push-buttons (CAGE, STD, + and -) and one BARO rotary knob. The controls are integral with the IESI bezel. The CTR BRT/DIM rotary-switch adjusts the LED intensity of the four push-buttons and the BARO rotary knob.
The + and - push-buttons let you adjust the brightness of the LCD display screen.
The CAGE push-button when pushed, starts the gyro-caging operation and the amber CAGE flag shows at the top right in the IESI display. This procedure cancels attitude errors, when the attitude difference of more than 1 degree between the IESI and the PFD display shows. This will cage the IESI attitude display (horizon) to zero. Subsequently, the white horizontal line aligns with the center dot and the slip/skid indicator aligns in the center position. Unusual aircraft maneuvers or aircraft configurations cause attitude errors. The gyro-caging operation works when the aircraft is in a straight and level flight path and the airspeed is stable.
The STD push-button sets the barometric correction to the standard (STD) value of 1,013.25 hPa/29.92 inHg. When the STD push-button is pushed, the white STD annunciation shows at the top center of the IESI display.
The BARO rotary knob lets you adjust the barometric value of the IESI. The value shows at the top of the IESI display. The value will increase when the knob gets turned clockwise and will decrease when the knob gets turned counterclockwise. The barometric correction value of the PFD and the IESI display are not related.
Eight flags which identify an operation in-progress or a problem can show on the IESI display. An acronym or a symbol identifies each of the flags that follow:
- The amber CAGE flag shows at the right at the top of the display, when the CAGING operation is started. The acronym CAGE identifies this flag. The cause for this condition: CAGE push-button pushed
- The amber SSEC flag shows at the right at the bottom of the display, when the SSEC law correction-formula can not calculate airspeed and altitude. The acronym SSEC identifies this flag. The cause for this problem: total pressure - static pressure (Pt/Ps) value not calibrated, no AOA, slat/flap angle input or an IESI internal fault
- The red ATT flag shows at the center of the display, when the IESI can not calculate attitude. The large symbol X identifies this flag. The cause for this problem: IESI not correctly aligned or an IESI internal fault
- The red IAS flag shows at the left side of the display and replaces the airspeed tape-scale. The flag shows when the IESI can not calculate airspeed and is identified as a large symbol X. The cause for this problem: total and/or static pressure value not calibrated, Pt/Ps value not calibrated or an IESI internal fault
- The red ALT flag shows at the right side of the display and replaces the altitude tape-scale. The flag shows when the IESI can not calculate altitude and is identified as a large symbol X. Because the altitude is not calculated, at the same time the IAS flag shows. The cause for this problem: static pressure value not calibrated or an IESI internal fault
- The amber ILS flag shows at the left corner at the top of the display, when the IESI can not show ILS deviation. The acronym ILS identifies this flag. The cause for this problem: no signal transmitted from the ILS receiver or an IESI internal fault
- The amber G/S flag shows at the right side of the display and replaces the glide slope scale. The flag shows when the IESI can not show glide slope deviation. The small symbol X identifies this flag. The cause for this problem: no signal transmitted from the ILS receiver or an IESI internal fault
- The amber LOC flag shows at the bottom of the display and replaces the localizer scale. The flag shows when the IESI can not show localizer deviation. The small symbol X identifies this flag. The cause for this problem: no signal transmitted from the ILS receiver or an IESI internal faul
05/10/16
System Interface
Standby Airspeed/Altimeter System
The standby airspeed/altimeter system interfaces to the systems that follow:
Secondary Power Distribution Assembly (SPDA) 1
SPDA 1 provides 28 VDC power from the DC ESS bus for the indicator's vibrator. The vibrator reduces the effects of friction and is located inside the altimeter.
Integral Lighting System
The integral lighting system supplies 5 VAC for the integral lights.
Pitot/Static System
The standby pitot/static probe supplies the pitot and static pressures.
Integrated Electronic Standby Instrument
The integrated electronic standby system interfaces with the systems that follow:
Secondary Power Distribution-Assembly (SPDA)
In an emergency condition, when primary aircraft power is not available, the IESI operates with 28 VDC. The SPDA 1 supplies 28 VDC through the AV BATT DIR BUS to the IESI. No pilot effect is necessary to operate the IESI.
Stall Protection System (SPS) (IESI INPUT)
Through the standard ARINC 429 input data-bus, the IESI receives SLAT, FLAP and body AOA discrete-signals from the SPS. The SPC CH B of the stall protection computer (SPC) sends the signals to the data-bus.
Stall Protection System (SPS) (IESI OUTPUT)
The IESI is a secondary air data source for the SPS.
Through two ARINC 429 output data-buses, the IESI sends the data that follows to channel A and channel B of the SPC:
- Calculated Airspeed (CAS)
- Mach
- Velocity Maximum Operating (VMO)
- Attitude Data
- Standard Altitude
- Baro-Corrected Altitude
- Baro Pressure (hPa/inHg)
- Maintenance Word
Integrated Avionics Computer (IAC) System (IESI INPUT)
From IAC 3, through the standard ARINC 429 input data-bus, the IESI receives the data that follows:
- METRIC altitude selection discrete-information
- ILS-LOC deviation data
- ILS-G/S deviation data
Panel Integral Lighting (IESI INPUT)
The IESI lighting power-supply is one of the primary components of the integral lighting system. The power supply changes 28 VDC input into 0–5 VDC output, for the IESI bezel lighting. The CTR BRT/DIM rotary-switch, installed on the COCKPIT LIGHTS (INTEGRAL) control-panel, adjusts the 0–5 VDC output. The COCKPIT LIGHTS (INTEGRAL) control-panel is installed in the center pedestal.
Air-Data Computer System (IESI INPUT)
The IESI uses the pitot and static pressures to help calculate the altitude and the indicated airspeed (IAS). The standby pitot static and the pitot static probe 1 connect at the rear of the IESI. The standby P/S probe gives the Pitot pressure (Pt) input. Static pressure (Ps) input is the average of the forward inlet of the standby P/S probe and the aft inlet of the P/S probe 1.
