INSTRUMENT LANDING SYSTEM (ILS)

INSTRUMENT LANDING SYSTEM (ILS)

 

Purpose

The instrument landing system (ILS) provides lateral and vertical position data neccessary to put the airplane on the runway for approach. The… The glideslope ground station transmits signals to give the airplane a descent… The localizer ground station transmits signals to give the

Abbreviations and Acronyms

· ACP - audio control panel · alt - alternate · altn - alternate

General

The instrument landing system (ILS) has two multi-mode

receivers (MMRs) that contain the ILS function. The ILS

function in the MMRs receive inputs from these antennas:

 

· VOR/LOC antenna

· Localizer antenna

· Glideslope antenna.

 

Description

The VOR/LOC antenna and the localizer antenna send localizer signals through the localizer antenna switches to the MMRs. The localizer antenna… The multi-mode receivers send ILS deviation data to these LRUs: · DEUs

COMPONENT LOCATION

Electronic Equipment Compartment

The multi-mode receivers (MMRs) are in the electronic equipment compartment. MMR 1 is on the E1-2 shelf. MMR 2 is on the E1-4 shelf. The LOC antenna switches are on the side of the E1 rack.

Nose Radome

The glideslope and localizer antennas are in the nose radome.

The glideslope antenna is above the weather radar antenna.

The localizer antenna is below the weather radar antenna.

 

 

POWER INTERFACES

Power Inputs

The P18-1 circuit breaker panel also contains the NAV SENSOR DC 1 and NAV SENSOR DC 2 circuit breakers. The circuit breakers receive 28v dc from the… The P6-1 circuit breaker panel contains the NAV CONT PNL 2 and the MMR 2… When you tune an ILS frequency on the NAV control panels, 28v dc goes to the on-side FCC and LOC antenna switch. The…

ILS - DIGITAL INTERFACE

General

These are the components that have a digital interface with the multi-mode receivers:

· Captain and first officer NAV control panels

· Flight data acquisition unit (FDAU)

· Standby attitude indicator

· Ground proximity warning computer (GPWC)

· Flight management computer (FMC) 1 and 2

· Display electronics units (DEU)

· FCC A and FCC B.

 

Digital Inputs

The NAV control panels supply frequency tune inputs to the multi-mode receivers. The NAV control panels also send tune inputs to the VOR and DME systems on a separate data bus.

Digital Outputs

The FDAU processes the data for the flight data recorder. The standby attitude indicator uses localizer and glideslope deviations for… The GPWC receives glideslope data from both ILS receivers for mode 5 (below glideslope) warnings.

ILS - FREQUENCY TRANSFER AND INSTRUMENT SWITCHING

General

The frequency transfer switch on the NAV control panel and the VHF NAV transfer switch on the navigation/displays source select panel have interface with the FCCs and DEUs.

Frequency Transfer Switch

 

The frequency transfer switch on the NAV control panel permits the crew to transfer the frequency from the standby display window on the NAV control panel, to the active display window. The transfer switch is a momentary action switch. When you push the switch, it changes the discrete level to the FCCs. The discrete tells the FCC when there is an ILS frequency change.

Navigation/Displays Source Select Panel

The VHF NAV switch on the navigation/displays source select panel is a three position switch. The positions are; BOTH ON 1, NORMAL, and BOTH ON 2.… In the NORMAL position, MMR 1 supplies data for the captain displays and MMR 2… When you select BOTH ON 2, MMR 2 is the source for the captains displays and first officers displays.

ILS - ANTENNA INTERFACE

General

The multi-mode receivers (MMRs) get RF inputs from these antennas: · VOR/LOC antenna on the vertical stabilizer · Localizer antenna in the nose radome

ILS - ANALOG INTERFACES

General

The FCCs send an ILS tune inhibit to the ILS function of the MMRs during the approach (APP) mode of operation. The ILS receiver will not accept… The PSEU sends air/ground discrete signals to the MMRs to set the flight leg… The MMRs send ILS ground station audio to the REU. The REU sends the audio to the flight compartment.

ILS - RECEIVER

Purpose

The multi-mode receiver contains an ILS receiver and a global positioning system (GPS) sensor unit. The ILS receiver function supplies localizer and glideslope deviation to different airplane systems. The GPS sensor unit supplies position data and time to the flight management computer system (FMCS).

Description

 

The MMR is a standard ARINC 600 3 MCU unit with dimensions 3.75 x 7.75 x 14.6 inches. The receiver weighs 10 pounds and uses 115v ac 400 Hz power for operation.

Test and Indication

 

There are status LED indicators and a test switch on the front of the multi mode receiver. The test switch starts a functional test of the receiver. The LED status indicators show test results.

 

 

ILS - ANTENNAS

Localizer Antenna

The localizer antenna has two elements. One element supplies RF inputs to ILS receiver 1 and one element supplies RF inputs to ILS receiver 2. The localizer antenna receives frequencies from 108.1 Mhz to 111.95 Mhz at odd tenth intervals.

Glideslope Antenna

The glideslope antenna also has two elements. One element supplies RF signal inputs to MMR 1 and one element supplies RF signal inputs to MMR 2. The glideslope antenna receives frequencies from 328.6 Mhz to 335.4 Mhz.

 

 

 

ILS - NAVIGATION CONTROL PANEL

General

 

The navigation (NAV) control panels supply frequency control and test signals to the DME, the MMR, and the VOR navigation radios.

Operation

The frequency transfer switch is a momentary action switch. It transfers the frequency in the standby frequency indicator to the active frequency… The frequency selectors are continuous rotary selectors. There is an inner… The NAV control panel continuous BITE function monitors the operation. The NAV control panel shows FAIL in the active…

Test

When you push the NAV control panel test switch, a test command goes out on the data bus. If a VOR frequency is active, the VOR receiver starts a self test. If an ILS frequency is active, the MMR receiver starts a self test. If a DME frequency is paired with the VOR or ILS frequency, the DME interrogator starts a self test at the same time.

When you do a test of the master dim and test system, the NAV control panel shows 188.88. The display shows for two seconds on, then one second off until the test is complete.

 

 

 

Power Interface

The NAV control panel uses 115v ac power for operation. It also uses 28v dc for an internal monitor. The NAV control panel uses 5v ac from the master dim and test for panel lights.

ARINC 429 Interfaces

Frequency tune inputs and test commands from the NAV control panel go to the MMR on an ARINC 429 bus.

When you tune an ILS frequency, the frequency tune circuits operate switches in the NAV control panel that send these discrete signals:

· Open discrete to the REU

· Ground discrete to the DEUs

· 28v dc to the FCCs

· 28v dc to the LOC antenna switches.

 

Discrete Interfaces

The REU uses the open discrete to select ILS audio. The DEUs use the ground discrete to set the ILS displays. The NAV control panel sends the 28v dc… The on-side FCC supplies a discrete during an AFDS approach mode. The discrete…

RF Interfaces

 

RF signals from the VOR/LOC antenna or localizer antenna in the nose radome, go to the localizer receiver circuits in the MMR. RF signals from the glideslope antenna in the nose radome go to the glideslope receiver circuits in the MMR.

ILS - FUNCTIONAL DESCRIPTION

Receiver Functional Description

All inputs to the receiver go through a high intensity radiated frequency (HIRF) filter. This filter provides protection to internal circuits. Tune inputs from the NAV control panel go to the main processor. The processor… The receiver circuits send the RF signal inputs from the

Test

To start an ILS test, push the NAV control panel test switch when there is an ILS frequency active or push the front panel test switch. When the processor receives a test signal, it does a test of operation and receiver condition. Test results show on the front panel LED status indicators. The LRU status LED shows red for test faults or green if there are no faults. The control fail LED comes on red if there is no tuning input data from the control panel. The control fail LED will show green for valid tune inputs.

 

 

ILS - CONTROLS

EFIS Controls

To show ILS data on the captain’s and F/O’s displays, set the mode selector on the EFIS control panel to the APP position.

DFCS Controls

The DEU uses the course input and ILS deviation to calculate the airplane’s deviation from the runway centerline. The DEUs compare the course input…

Audio Control Panel Controls

You use the ACP receiver switches to select the ILS audio you want to listen to. The NAV 1 receiver switch selects the MMR 1 audio and the NAV 2…    

ILS - STANDBY ATTITUDE INDICATOR DISPLAYS

General

The standby attitude indicator gives the crew an alternate attitude indication source. The indicator also provides ILS data. You use the approach selector on the indicator to show ILS data. The approach selector has these positions:

· Off - no ILS data on indicator

· APP - ILS localizer and glideslope data shows

· B/CRS - back course ILS localizer data shows.

 

Indications

When the indicator receives invalid ILS data, the localizer or glideslope deviation bars go out of view and the glideslope flag or localizer flag… When the ILS data is no computed data (NCD) for localizer or glideslope data,…  

General

To show ILS displays on the ADI you must tune a valid ILS frequency on the NAV control panel and select it to the active display window.

Normal Display

The localizer scale can show the standard display or the expanded scale. A two-dot expanded scale can replace the four-dot scale. For the expanded… The expanded scale shows for these conditions: · LOC deviation is less than 5/8 dot

Rising Runway

The rising runway shows when there is a LOC signal capture and the radio altitude is below 2500 feet. The symbol goes out of view above 2500 feet.… The rising runway symbol represents the radio altitude above the runway. It…

NCD Display

 

When the ILS data goes to an NCD condition, the CDS shows the localizer and glideslope scales and removes the pointers.

Fail Display

 

The amber LOC flag replaces the localizer deviation pointer

and scale when the localizer receiver function has a failure. The

amber G/S flag replaces the glideslope deviation pointer and

scale when the glideslope receiver function has a failure.

 

 

ILS - EXPANDED ILS DISPLAY

General

To show ILS displays on the CDS, set the EFIS control panel mode selector to the APP position. You must also tune a valid ILS frequency on the NAV control panel.

Normal Display

The glideslope scale is the standard four dot scale where each dot equals 0.35 degrees of deviation. The glideslope deviation pointer gives fly-to… The localizer deviation indicator and scale shows at the bottom of the NAV… The deviation scale is the standard four dot scale. One dot is equal to 1 degree of deviation. The localizer deviation…

NCD Display

When the ILS data goes to an NCD condition, the CDS shows the localizer and glideslope scales and removes the pointers.

Fail Display

For invalid ILS data, the CDS replaces the localizer deviation

scale and indicator with the amber LOC flag when the localizer

receiver fails. The amber G/S flag replaces the glideslope

deviation scale and pointer when the glideslope receiver fails.

ILS - CENTERED ILS DISPLAY

General

To show the centered ILS NAV display, push the CTR switch on the EFIS control panel mode selector switch.

Normal Displays

The glideslope scale is the standard four dot scale. Each dot equals 0.35 degrees of deviation. The pointer gives fly-to commands to intercept the… The course pointer points to the number that you set on the DFCS MCP. For ILS,… The localizer deviation indicator and scale show in the center of the HSI compass card. The localizer deviation…

NCD Display

For an ILS NCD condition, the CDS displays the localizer and glideslope scales and removes the deviation bar and glideslope pointer.

Fail Display

For invalid ILS data, the CDS replaces the localizer scale and deviation indicator with the amber LOC flag when the localizer receiver fails. The amber G/S flag replaces the glideslope scale and pointer when the glideslope receiver fails.

 

 

 

 

Test

When you push the test switch, the MMR does a check of the internal operation and its interface with other airplane systems. The test takes approximately 36 seconds. This is the test sequence that shows on the LED status indicators during the test:

· 0 to 2 seconds - the LRU STATUS, the CONTROL FAIL, and the ANT FAIL LEDs come on red

· 2 to 4 seconds - the LRU STATUS LED is green and theCONTROL FAIL LED is red

· 4 to 6 seconds - all LEDs go off

· 6 to 36 seconds - test status shows.

 

The LRU STATUS segment shows red when there is an internal failure in the MMR. Green shows that the MMR is operating normally.

The CONTROL FAIL segment shows red when an interface to the MMR has a failure. Green shows that all the interfaces to the MMR are normal.

NOTE: The ANT FAIL LED is not used at this time.

 

 

ILS - SELF-TEST

Test

You use the NAV control panels to do an ILS test from the flight compartment. The captain NAV control panel does a test of MMR 1 and the first officer NAV control panel does a test of MMR 2.

You need to set these controls to do an ILS test:

· Enter a valid ILS frequency into the active frequency display window on the NAV control panel

· Set a course on the DFCS mode control panel that is within

Degrees of the airplane heading

To see the ILS test on the NAV display, you must select the approach (APP) mode on the EFIS control panel mode selector. This is the display… · For the first 3 seconds, one dot left of localizer deviation and one dot up… · For the next 3 seconds, one dot right of localizer deviation and one dot down of glideslope deviation