Q72-34-015 r004 · BOEING 737-300/400/500 Q72-34-015 Page 1 of 98 Q72 - MAINTENANCE INSTRUCTION QANTAS AIRCRAFT MAINTENANCE MANUAL CHAPTER 34 EFFECTIVITY VH-TJE thru VH-TJU, VH-TJW,

BOEING 737-300/400/500

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Q72 - MAINTENANCE INSTRUCTION

QANTAS AIRCRAFT MAINTENANCE MANUAL

CHAPTER 34

EFFECTIVITYVH-TJE thru VH-TJU, VH-TJW,VH-TJX thru VH-TJZ,VH-XMB, VH-XML,VH-XMO, VH-XMR

SUBJECT: ENHANCED GROUND PROXIMITY WARNING SYSTEMDESCRIPTION AND OPERATION

1. FOREWORD:

This Maintenance Instruction contains the relevant instructions to maintain the AlliedSignal Enhanced Ground Proximity Warning System (EGPWS) that is being installedthroughout the Qantas 737 fleet.

2. BACKGROUND:

The purpose of the Enhanced Ground Proximity Warning System is to help preventaccidents caused by Controlled Flight Into Terrain (CFIT). The Enhanced GroundProximity Warning System (Allied Signal Mk V EGPWS) is an improved groundproximity warning system to replace that already installed in the 737 fleet (Allied SignalMk V GPWS). The most important new features of the EGPWS that were not available tothe GPWS are Terrain Awareness Alerting and Display functions. These functions use theaircraft’s geographic position and altitude and the internal terrain database to predictpotential conflicts between the aircraft flight path and the terrain and optionally providegraphic displays of the conflicting terrain.

3. EFFECTIVITY:

There are two simple ways of determining whether an aircraft has EGPWS installed. Firstof all, in the cockpit two additional annunciator panels are installed (one in P3, the other inP1). Each of these includes two annunciator/switches that are marked “WXR” and“TERR”. The annunciator panel in P1 also includes a guarded switch marked“OVRD/INOP”. These two annunciator panels are ONLY installed in aircraft that havebeen retrofitted with EGPWS. A second test is simply to check the part number of theground proximity warning computer in the E/E bay (this computer is located on E2-4 for300 series aircraft and E2-2 for 400 series aircraft. If the part number of the computer is965-0976-020-210-210 or subsequent then the aircraft is installed with EGPWS.

NOTE: This Maintenance Instruction replaces the Boeing Maintenance Manual chapters34-42-01, 34-42-11, 34-42-02 and 34-42-21 for aircraft fitted with EGPWS.

4. PROCEDURE:

Refer Appendix 1.

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CHAPTER 34BOEING 737-300/400/500


5. MAINTENANCE SYSTEMS REFERENCES:

• AMM 34-42-01 Ground Proximity Warning System

• AMM 34-42-11 Computer – Ground Proximity Warning

• AMM 34-42-02 Ground Proximity Warning System

• AMM 34-42-21 Module – Ground Proximity Warning

• ASM Installation Information/Documentation for EGPWS kit Part NumberK5543-0000-00

• Allied Signal Document No. 060-4199-014: Line Maintenance Manual for theEnhanced Ground Proximity Warning Computer Part Number965-0976-0XX-XXX-XXX.

• Allied Signal Document No. 060-4167-147: Production Ground Test Procedure for the EGPWS Installation, Qantas Airways, B737-300/-400 with Internal GPS.

• Maintenance Memo – Enhanced Ground Proximity Warning System (EGPWS) recommended response to “Terrain Inop” Light. Memo number not available attime of issue.

• PM Research shop manual Antenna Erosion Protective Mask PM570 Sensor Systems GPS S67-1575-133.

• “Enhanced Gpws System Update” Qantas training document produced by the Qantas Engineering School.

• Engineering Instructions: EI 733-034-160 (EGPWS Installation on 737-300)EI 733-034-196 (EGPWS Callout Upgrade and activationof Obstacle feature – freighter)EI 734-034-055 (EGPWS Installation on 737-400)EI 734-034-077 (EGPWS Callout Menu Update toinclude 500 callout on 737-400)

• Cameo Task: 737-B34-42-01-5A

• Boeing Comm QAN-QAN-10-1341-02B dated 09 Nov 2010

• MPAR 73742510

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ENHANCED GROUND PROXIMITY WARNING SYSTEM

APPENDIX 1

TABLE OF CONTENTS

SUBJECT PAGE

4. PROCEDURE:

A. GENERAL .................................................................................................................. 5(1) System Description ............................................................................................. 5(2) Main Features Of EGPWS .................................................................................. 6(3) Internal Data Handling........................................................................................ 6(4) System Components............................................................................................ 7(5) Enhanced Ground Proximity Warning Computer ............................................... 8(6) EGPWS Warning Lights ..................................................................................... 9(7) Windshear Warning Lights.................................................................................. 9(8) Glideslope Warning Lights................................................................................ 10(9) Ground Proximity Warning System Control Module ....................................... 11(10) Warning Speaker ............................................................................................... 11(11) EGPWS Annunciator Panel .............................................................................. 12(12) Display Switching Relays ................................................................................. 12(13) GPS Antenna..................................................................................................... 12(14) Operation........................................................................................................... 12

B. GROUND PROXIMITY SYSTEM – TROUBLE SHOOTING.......................... 40(1) General .............................................................................................................. 40(2) TERRAIN INOP” Light.................................................................................... 42(3) EFIS EHSI “GND PROX SYS” Message ........................................................ 44(4) EFIS EHSI “WINDSHEAR SYS” or “WINDSHEAR REAC” message......... 45(5) Prepare For Trouble-Shooting........................................................................... 45(6) Self Test Function.............................................................................................. 46(7) General Troubleshooting Guide ........................................................................ 61

C. GROUND PROXIMITY WARNING SYSTEM – ADJUSTMENT/TEST......... 62(1) General .............................................................................................................. 62(2) Ground Proximity Warning System - Operational Test .................................... 62(3) Ground Proximity Warning System - System Test ........................................... 65

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APPENDIX 1

D. GROUND PROXIMITY WARNING COMPUTER – INSTALLATION/REMOVAL................................................................................. 83(1) General .............................................................................................................. 83(2) Ground Proximity Warning Computer Removal .............................................. 83(3) Ground Proximity Warning Computer Installation........................................... 84

E. GROUND PROXIMITY WARNING MODULE – SERVICING(BULB REPLACEMENT)....................................................................................... 87(1) General .............................................................................................................. 87(2) Ground Proximity Warning Module Bulb Replacement................................... 87

F. GROUND PROXIMITY WARNING MODULE –REMOVAL/INSTALLATION................................................................................ 89(1) General .............................................................................................................. 89(2) Ground Proximity Warning Module Removal .................................................. 89(3) Ground Proximity Warning Module Installation .............................................. 90

G. EGPWS ANNUNCIATOR PANEL – REMOVAL/INSTALLATION................. 91(1) General .............................................................................................................. 91(2) EGPWS Annunciator Panel Removal ............................................................... 91(3) EGPWS Annunciator Panel Installation ........................................................... 92

H. GPS ANTENNA – REMOVAL/INSTALLATION ................................................ 93(1) General .............................................................................................................. 93(2) GPS Antenna Removal ..................................................................................... 93(3) GPS Antenna Installation.................................................................................. 94

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APPENDIX 1

A. GENERAL

(1) System Description

The ground proximity warning system (EGPWS) provides the pilots with auraland visual warning of potentially dangerous flight paths relative to the ground.The EGPWS processes signals from digital analog adapter No. 1 and 2, VHFNAV receiver No. 1 and 2, radio altimeter No. 1 and 2, digital air data computerNo. 1 and 2, inertial reference unit no. 1 and 2, digital stall warning computers 1and 2, flight management computer, flap warning switches, landing gear logicshelf and the landing gear lever, and receives position information from a GPSantenna connected to an internal GPS receiver.

Figure 1

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APPENDIX 1

(2) Main Features Of EGPWS

(a) Excessive rate of descent (Mode 1)

(b) Terrain Closure Rate (Mode 2A/2B)

(c) Descent After Takeoff (Mode 3)

(d) Insufficient Terrain Clearance (Mode 4A/4B/4C)

(e) Descent Below Glideslope (Mode 5)

(f) Altitude Callouts (Mode 6)

(g) Excessive Bank Angle Callout

(h) Windshear Detection (Mode 7)

(i) Terrain Clearance Floor

(j) Terrain Awareness Alerting and Display

(3) Internal Data Handling

(a) Envelope Modulation

The envelope modulation feature consists of storing information aboutpeculiarities of particular approaches and departures where modes 1, 2, 4,5, and 6 are not entirely appropriate as they are generally implemented.This stored information is used to first of all verify the airplane locationand configuration, and then to alter the basic mode parameters as necessaryto optimize GPWS performance.

(b) Programmable Data Tables

There are six types of data that have been incorporated into programmablenon-volatile memory: envelope modulation parameters, mode 6 altitudecall-out menus, mode 7 windshear constants and thresholds, terrain (anaccurate global relief map of the world), obstacles (an overlay of manmadeobjects that may threaten an aircraft) and runways (the layout of runways inexcess of 3,500’ in length for the Terrain clearance Floor cautions).

1) This data is accompanied by version/data information. These datatables are in addition to the power immune latches and flight historyinformation that is also stored in this non-volatile memory. The maindifference between these two types of information is that the datatables can not be written to except on the bench (i.e. read only via ahardware strap).

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APPENDIX 1

(c) BITE and Flight History

1) There exists within the GPWS software, built in test equipment orBITE. Much of this BITE is run continuously, while some tests are runonly as the result of certain events (e.g. power up, self-test, etc.). ThisBITE is capable of logging failure for the last 10 flight legs innon-volatile flight history memory storage for later recovery.

(4) System Components

The EGPWS consists of an enhanced ground proximity warning computer; twowarning lights labeled PULL UP; two glide slope warning indicator/inhibitswitches labeled BELOW Glideslope; a ground proximity warning controlmodule which consists of a SYS TEST switch, an EGPWS failure monitorINOP light, Captain’s and F/O’s annunciator panels, and one GPS antenna.Equipment location is shown on subsequent pages

The EGPWS control module has a guarded FLAP INHIBIT switch and aguarded GEAR INHIBIT switch.

Primary power for the system is 115 volts ac supplied from the essential radiobus in panel P18 through a circuit breaker labeled GND PROX WARN. Thewarning indicator lights receives 28 volts dc power from the master dim and testsystem (Refer Chapter 33).

Figure 2

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APPENDIX 1

(5) Enhanced Ground Proximity Warning Computer

(a) Location Of Computer

The enhanced ground proximity warning computer (EGPWC) israck-mounted on shelf No. 2 (VH-XMB, VH-XML, VH-XMO andVH-XMR) or shelf No. 4 (VH-TJE through VH-TJO, VH-TJR throughVH-TJZ) of electronic equipment rack E2.

(b) Computer Input Signals

The computer receives glide slope deviation, barometric altitude rate, radioaltitude, gear and flap logic, airplane position and flight path accelerationinformation from other airplane systems, and GPS position from the GPSantenna. The input signals are processed and signals are provided towarning devices if the airplane enters an unsafe flight path.

Figure 3

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APPENDIX 1

(6) EGPWS Warning Lights

A rectangular shaped red warning light labeled PULL UP is installed on thecaptain’s and first officer’s instrument panels. Access to the bulbs within thelight assembly is provided by removing the lens cover.

The lights come on to provide a visual indication of mode 1 2, 3, and 4warnings.

(7) Windshear Warning Lights

(a) 737-300 Aircraft

On 737-300 airplanes, a rectangular shaped red warning light labeledwindshear is installed on both the captain’s and first officer’s instrumentpanels. The bulbs and a fuse within the light assembly may be accessed byremoving the lens cover. The lights come on to provide a visual indicationof a windshear condition.

(b) All Except 737-300 Aircraft

On ALL EXCEPT 737-300 airplanes, the visual indication of a windshearcondition is provided on both the captain’s and first officer’s EADI. Duringwindshear conditions, WINDSHEAR will be displayed in red on the EADIball approximately 1/3 up from the bottom.

Figure 4

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APPENDIX 1

(8) Glideslope Warning Lights

(a) Glideslope, Below Glideslope Lights

A rectangular shaped amber Glideslope (advisory) light labeled BELOWGlideslope is installed on the captain’s and first officer’s instrument panels.Access to the bulbs and a fuse within the light assembly is provided byremoving the lens cover. The light comes on to provide a visual indicationthat the airplane is below the glide slope beam when an ILS frequency isselected.

Figure 5

(b) Glideslope Warning Light

The Glideslope warning eight will inhibit the glide slope deviation warningwhen pressed, provided the hard glide slope warning is not already on.

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APPENDIX 1

(9) Ground Proximity Warning System Control Module

The ground proximity warning control module is located on the first officer’sinstrument panel. It consists of an amber INOP indicator light, a SYS TESTswitch, a guarded and lockwired FLAP INHIBIT switch and a guarded andlockwired GEAR INHIBIT switch. The INOP indicator light comes on whenthe monitor circuit in the computer senses a fault condition. The TEST switchprovides a confidence check of the system, either in flight or on the ground. TheFLAP INHIBIT switch enables the pilots to simulate a flap down condition andthe GEAR INHIBIT switch enables the pilots to simulate a gear down conditionwhen the switches are set to INHIBIT position. When placed in the INHIBITposition, the TOO LOW FLAPS and TOO LOW GEAR warnings are inhibited.

Figure 6

(10) Warning Speaker

The aural warning signals from the EGPWC are sent to the remote electronicunit (Shelf 1, equipment rack No. 2) to be processed. The aural warnings arethen broadcast over the cockpit speakers (pilots overhead panel P5) and theflight interphone system.

Figure 7

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APPENDIX 1

(11) EGPWS Annunciator Panel

The First Officer’s EGPWS Annunciator Panel is located in panel P3-3 of theF/O’s instrument panel. It includes the TERR and WXR annunciator/switches.The Captain’s EGPWS annunciator panel is located in panel P1-3 of theCaptain’s instrument panel. It consists of the TERR and WXR annunciator/switches as well as an OVRD/INOP annunciator. The EGPWS annunciatorpanels allow for selection of Weather Radar or Terrain for display on theelectronic Navigation Display (ND) via the TERR and WXR annunciator/switches. These annunciators are mutually exclusive two position switches,which select the indicated source for display when set to the lit (on) position.The OVRD/INOP annunciator on the Captain’s annunciator panel is a guardedswitch, which provides for annunciation of the “Terrain Not Available” modeand activates the “Terrain Inhibit” mode when selected to the OVRD position.

(12) Display Switching Relays

Switching between Weather Radar and Terrain for display on the NavigationDisplay is accomplished by the display switching relays. These are controlledby the TERR and WXR annunciator switches located in the cockpit. The defaultposition allows for display of Weather radar. Power for these relays is providedvia the newly installed TERRAIN DISPLAY circuit breaker.

(13) GPS Antenna

The GPS antenna is located on the roof of the aircraft at station 500A and isconnected via coaxial cable to an internal GPS receiver within the EGPWC. TheGPS provides position information to the EGPWS.

(14) Operation

(a) Requirements for EGPWS Operation

The EGPWS is operational when load control centers P18 and P6 areenergized and the following system circuit breakers are closed: groundproximity warning, Terrain Display, No. 1 air data, No. 1 VHF navigation,No. 1 inertial reference, No. 1 digital analog adapter, stall warning, flightmanagement, flight interphone, and EFIS.

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APPENDIX 1

(b) Signal Inputs to the EGPWC

Signal inputs to the EGPWC consist of position information from GPS,radio altitude information from LRRA No. 1, mach and altitude rateinformation from central air data computer No. 1, and glide slope deviationfrom the VHF NAV system.

1) Aircraft Position, latitude and longitude are required for EGPWSoperation and are preferably received from an integrated GlobalPositioning System (GPS). Flight Management System (FMS) orInertial Reference System (IRS) data may be utilized if GPS data is notavailable, but the Terrain Threat Detection and Display will only beenabled if the quality of the FMS data is sufficient. Additionally,aircraft Ground Track and Ground Speed data are also received fromthe GPS (or FMS or IRS).

2) The LRRA system provides the GPWS with radio altitude, and analtitude trip when the airplane descends below the decision height(mode 6, when activated) set on the captain’s radio altitude indicator.LRRA signals are used in the control of modes 1 through 6. Mode 2requires a radio altitude rate signal (terrain closure rate) which isderived by the computer from the radio altitude signal. The radioaltitude signal is a dc voltage that is a function of airplane height aboveground level and is useful to approximately 2500 feet.

3) The CADC system provides mach and barometric altitude rate signalsto the GPWS computer. Altitude rate is used for the computations ofmode 1 conditions, and is used to derive altitude loss, used in thecomputation of mode 3 conditions. The barometric rate signal is acwith a scale of 250-mV/1000 fpm altitude change. This rate signal is inphase with the 26-volt ac reference from the CADC during ascent andout-of-phase during descent. The mach signal is used to set warningthresholds for mode 2 and mode 4 computations. It is a three wiresynchro output calibrated from zero degrees for 0.2 mach indicationand increasing to one synchro revolution for a 1.2 mach indication.

4) The VHF navigation system provides glide slope deviation signal thatis used in the mode 5 computation. The glide slope deviation signalprovides a low level input with a sensitivity of 75 mV/deviation dot.

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APPENDIX 1

(c) Binary Inputs to the EGPWC

Binary inputs to the EGPWC consist of a landing gear and landing flapposition signal and 28-volt dc radio altimeter valid, glide slope valid andbaro rate computer valid signals.

The landing gear lever switch actuation is determined by the position of thelanding gear control lever. When the lever is moved to the down detentposition, the microswitch is actuated. Switch actuation provides a groundto the enhanced ground proximity warning system, indicating that thelanding gear lever is in the down position. The ground from the landinggear lower switch is also provided to the landing gear accessory module.

The landing flap position warning switch is set to actuate at 15 units offlaps, and the takeoff flap position warning switch is set to actuate at 25units of flaps. The objective of these two switches is to provide a ground tothe EGPWC for flap settings of less than 25 units. One switch providesground for settings of 5 to 25 units. The second switch provides coveragefor flaps up (0 units) by providing a ground for settings of 5 to 15 units.With either switch closed, a ground is provided to the enhanced groundproximity warning computer, arming the TOO LOW-FLAPS warning.When the flaps are in a landing configuration, both switches are open andthe warning is inhibited.

The air/ground relay supplies a binary input to the EGPWC. The air/groundinput allows the EGPWC to inhibit mode functions while the airplane is onthe ground to decrease nuisance warnings when the airplane is in the air,the air/ground input inhibits testing of the EGPWC.

(d) Databases

The EGPWC includes 3 databases that are regularly updated and are usedfor terrain alerting and awareness.

1) Terrain database

Topographic surface data is used for local terrain processing of updatesa set of Digital Elevation Matrix Overlays that are positioned withrespect to Aircraft Position. Each matrix element contains the highestterrain altitude with respect to mean sea level in that element’s area.Elements where terrain data are not available are marked invalid.

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APPENDIX 1

2) Man made obstacle database

In addition to terrain surface data, provisions are made for use of anObstacle Database providing obstacle data near major airports. LocalTerrain Processing will update a dedicated overlay within the DigitalElevation Matrix Overlays with local obstacle altitude data.

3) Runway database

Data for the nearest runway are extracted and processed for use by theTerrain Threat Detection and Display Processing functions. Data areextracted from the same Airport Database used by the TerrainClearance Floor functions. This database contains data on all runways3,500 feet or more in length. The contents of the database areprocessed by the Local Terrain Processing into Nearest Runway Centreposition, Nearest Runway Threshold position and Nearest RunwayAltitude for use by the EGPWS. These data are updated when theTerrain Threat Detection and Display Processing functions areperformed.

Figure 8

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APPENDIX 1

(e) Voice Messages

The EGPWC provides ten different voice messages With the possibility ofmore than one warning occurring at the same time, the following priorityhas been established with the associated modes The highest prioritymessage is always provided If a higher priority warning occurs, themessage will immediately switch to the higher priority message If a higherpriority warning stops, the priority message will complete before switchingto any lower priority message.

Priority Message Mode1 WINDSHEAR 72 WHOOP WHOOP PULL UP 1 and 23 TERRAIN 24 TOO LOW TERRAIN 45 TOO LOW GEAR 4A6 TOO LOW FLAPS 4B7 SINK RATE 39 DON’T SINK 310 GLIDE SLOPE 511 (Various altitude callouts – when activated) 6

NOTE: Windshear aural message is preceded by one cycle of siren sound.

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APPENDIX 1

(f) Modes of Operation

The EGPWC processes the input signals to provide warning outputs duringthe following flight conditions:

1) Excessive Sink Rate Warning (Mode 1)

a) Mode 1 provides pilots with alert/warning for high descent ratesinto terrain. When the Alert envelope is penetrated, the message“SINK RATE” will be annunciated and the EGPWS alert lightswill illuminate. The message “PULL UP” will annunciate and theEGPWS warning lights will illuminate when the Warningenvelope is penetrated.

Figure 9

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APPENDIX 1

Figure 10

2) Terrain Closure Rate (Mode 2A/2B)

a) Mode 2A and 2B each provide two types of alert/warnings to warnof dangerously high closure rates towards terrain. Mode 2A isactive when flaps are NOT on an ILS approach within ±2 dots ofglideslope deviation. Mode 2B is active when the flaps are in thelanding position, or while on an ILS approach within ± 2 dots ofglideslope deviation. The aural annunciation for this mode is“TERRAIN TERRAIN PULL UP”.

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APPENDIX 1

Figure 11

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APPENDIX 1

Figure 12

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APPENDIX 1

3) Takeoff Altitude Loss Warning (Mode 3)

a) A warning consists of visual PULL UP and aural DON’T SINK isprovided when the airplane is in takeoff mode before acquiring700-foot terrain clearance with landing gear or flaps up and abarometric altitude loss is detected as shown. The altitude lossrequired to activate the warning varies with the height of theairplane above the ground at the time inadvertent descent occurs.At a climbout altitude of 100 feet any loss of altitude will activatethe warning. At 700 feet, an altitude loss of 70 feet will activate thewarning.

b) A magnetic latch provides logic between mode 3 and 4. Duringtakeoff, the latch is set to arm the takeoff mode and disarming theterrain clearance warning. Upon acquiring 700 feet of altitude, thelatch resets, arming the terrain clearance warning.

Figure 13

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APPENDIX 1

Figure 14

4) Unsafe Terrain Clearance Warning (Mode 4A/4B/4C)

Mode 4 generates three types of alerts based on radio altitude, terraindatabase, position, airspeed and flight mode. These are referred to asMode 4A, 4B and 4C. Mode 4A is active during cruise and approachwith landing gear up. Mode 4B is active during cruise and approachwith landing gear down and flaps up. Mode 4C is active during takeoff.Warnings from Mode 4A, 4B and 4C cannot happen simultaneously.The aural warnings for Mode 4A/4B/4C are “TOO LOW GEAR”,“TOO LOW FLAP” and “TOO LOW TERRAIN”.

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APPENDIX 1

Figure 15

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APPENDIX 1

Figure 16

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APPENDIX 1

5) Glide Slope Deviation Warning (Mode 5)

a) The glide slope warning is armed when an ILS frequency isselected. The warning envelope consists of two regions as shown.The BELOW C/S indicators accompanied by a reduced volume ofaural warning GLIDE SLOPE come on, if the deviation of theairplane below the glide slope exceeds 1.3 dots between 1000 and150 feet of radio altitude and the gear is down. The aural warningincreases to full volume, hard warning, if the deviations of theairplane below the glide slope exceeds 2 dots when the airplane isbetween 300 and 150 feet of radio altitude.

b) In order to allow the pilot to purposely descend below the glideslope without triggering a warning, the glide slope warning modemay be inhibited by pressing the BELOW Glideslope indicatorwhen the radio altitude is below 1000 feet. To again enableMode 5, the airplane is required to ascend to a terrain clearance ofgreater than 1000 feet.

Figure 17

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APPENDIX 1

Figure 18

6) Decision Height Warning (Mode 6)

a) The computer will provide the following callouts as the airplanedescends through the corresponding radio altitudes.

Post EI 734-34-77, 733-34-196:

Aural Radio Altitude“Radio Altimeter” 2500 ft“One Thousand” 1000 ft“Five Hundred” 500 ft“One Hundred” 100 ft“Fifty” 50 ft“Thirty” 30 ft“Twenty” 20 ft“Ten” 10 ft

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APPENDIX 1

Pre EI 734-34-77 (737-400)

Aural Altitude“MINIMUMS”“100” 100 ft“50” 50 ft“30” 30 ft“10” 10 ft

Pre EI 733-34-196 (737-300 freighter)

Aural Altitude “50” 50 ft“30” 30 ft“10” 10 ft

NOTE: “Minimums” occurs at ± 5 ft of decision height.

7) Excessive Bank Angle Callout

a) The Bank angle feature provides protection for over bankingduring maneuvering on approach or climbout and while at altitude.In addition, it protects against wing or engine strikes close to therunway. An aural warning of “BANK ANGLE” messages is given.Follow-on messages are only allowed when the aircraft roll angleincreases an additional 20% from the previous alert.

b) QAN 068-999;

The aural warning “bank angle” will occur when the airplane hasexceeded a 35 degree bank.

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APPENDIX 1

8) Windshear (Mode 7)

a) The windshear comparator receives data inputs from the ARINC429 receiver, in addition to flap position information. Using analgorithm which provides different gain and threshold levels fortakeoff and approach modes, and which also provides altitude-dependant gain levels, the windshear comparator computes bothvertical and horizontal windshear components.

b) The vertical windshear component is computed from data from thestall warning computer (vane AOA), the digital air data computer(true airspeed), and the IRS (body pitch rate). These data arecombined with inertial vertical speed, pitch attitude, and rollattitude in order to determine the total vertical component ofwindshear.

c) Horizontal windshear is computed by utilizing DADC trueairspeed and flight path acceleration from the IRS.

d) The audio message for a windshear condition consists of one cycleof the siren audio (250 and 950 Hz) followed by the distinct wordsWINDSHEAR.

e) When the EGPWC is in a windshear alert mode, all other EGPWSmodes are inhibited.

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APPENDIX 1

9) Terrain Clearance Floor

a) Terrain clearance floor (TCF) alerts the flight crew when theairplane descends too low on approach. TCF uses airplane positionand a runway database to determine if an alert condition exists.

b) The EGPWC stores a runway database in memory. This databasecontains the location of all hard surface runways in the world thatare 3,500 feet or more in length. TCF makes a terrain clearanceenvelope around the runway. The altitude of the envelopeincreases as the distance from the airport increases. EGPWCcompares airplane latitude, longitude, and radio altitude with TCFenvelope data. If the airplane descends through the floor of theenvelope, GPWC makes an alert. TCF makes an alert even if theairplane is in landing configuration.

c) If the GPWC determines the airplane is below the TCF, it makesthis caution alert:- Aural message TOO LOW TERRAIN. This message repeats

for each 20 percent loss of altitude.- The ground proximity PULL-UP warning lights comes on and

stay on until the airplane climbs above the TCF.

There is no TCF warning alert.

The GPWC inhibits TCF alerts for any of these conditions:- Airplane is on the ground- Less than 20 seconds after takeoff- Less than 30 feet radio altitude

Figure 19

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APPENDIX 1

10) Terrain Awareness Alerting and Display

a) Terrain awareness alerting algorithms continuously computeterrain clearance envelopes ahead of the aircraft. If the boundariesof these envelopes conflict with terrain elevation data in the terraindatabase, then alerts are issued. Two envelopes are computed, onecorresponding to a Terrain Caution Alert level and the other to aTerrain Warning Alert level. The algorithms are designed to meetthe following criteria:

• Operational Compatibility – Minimal unwanted alerts duringnormal flight operations and approach procedures.

• Improved Terrain Awareness Warning Times – Provideadequate alert times for all flight phases and conditions.

• Robustness – Tolerant of aircraft position errors, altitudesignal errors, and database errors.

b) The Caution and Warning envelopes use the Terrain ClearanceFloor as a baseline, and virtually “look ahead” of the aircraft in avolume which is calculated as a function of airspeed, roll attitudeand flight path angle.

c) If the aircraft penetrates the Caution Envelope boundary, the auralmessage “Caution Terrain, Caution Terrain” is generated, and alertdiscretes are activated for visual annunciation. Simultaneously, theconflicting terrain areas are shown in solid yellow colour on theTerrain Display.

d) If the aircraft penetrates the Warning envelope boundary, the auralmessage “Terrain Terrain, Pull Up!” is generated, and alertdiscretes are activated for visual annunciation. Simultaneously theconflicting terrain areas are shown in solid red colour on theTerrain Display.

e) Provision has been included for an obstacle database providingsimilar annunciation when catalogued obstacles violate the sameenvelope boundaries.

f) The EGPWS alert lamps and audio outputs behave in the samemanner as the standard GPWS mode alerts. A Terrain CautionAlert or Terrain Warning Alert will initiate a specific audio alertphrase.

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g) Complementing the terrain threat alerts, the EGPWS alsomaintains a synthetic image of local terrain forward of the aircraftfor display on EFIS EHSIs. This imposes strict timingrequirements on the EGPWS functions to insure the image isaccurate and up-to-date on each synthetic radar display sweep.

h) The EGPWS is configured to automatically de-select the WeatherDisplay and “pop-up: a display of the terrain threats when theyoccur.

i) The Terrain/Obstacle Threat Detection and Display processingfunction performs the threat analysis on the terrain/obstacle datawithin computed caution and warning envelope boundaries belowand forward of the aircraft path. Results of threat assessments arecombined with background terrain data and nearest runway dataand formatted into a terrain display image, which can be displayedon an EFIS display in place of the weather image. In the event ofterrain/obstacle caution or warning conditions, a specific audioalert is triggered, the red PULL-UP lights illuminate and the terraindisplay image is enhanced to highlight each of the types of terrainthreats.

j) The basic Terrain Caution Envelope (or Yellow Alert Envelope)and Terrain Warning Envelope (or Red Alert Envelope)boundaries are illustrated.

k) A perspective view of the Terrain Detection envelope is illustrated.

l) The Caution Altitude Floor (or Terrain Floor) is computed as afunction of Aircraft Altitude with respect to Nearest RunwayElevation and range to the Nearest Runway Threshold position.This parameter represents a distance below the aircraft. Therelationship to the nearest runway threshold location preventsundesired alerts when the aircraft is taking off or landing at anairport. The system is compatible with terrain clearances allowedfor by regulatory approach and departure design criteria.

m) The Caution Look Ahead Distance is computed from aircraftground speed and turn rate to provide an advanced warning withadequate time for the crew to react safely. Depending on thesituation, this distance roughly corresponds to between 40 and 60seconds of advance alerting.

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n) The Warning Altitude Floor is set to a fraction of the CautionAltitude Floor. The Warning Altitude Floor is computed as afunction of Aircraft Altitude with respect to Nearest RunwayElevation and range to the Nearest Runway Threshold position.This parameter represents a distance below the aircraft. Therelationship to the nearest runway threshold location preventsundesired alerts when the aircraft is taking off or landing at anairport.

o) The Warning Look Ahead Distance is a fraction of the CautionLook Ahead Distance (computed from aircraft ground speed andturn rate) to provide an advanced warning with adequate time forthe crew to react safely.

p) The Terrain Awareness Alerting and Display function maintains aBackground Display of local terrain forward of the aircraft forcockpit display. In the event of terrain caution or warningconditions, an aural alert is triggered. The background image isthen enhanced to highlight related terrain threats forward of theaircraft.

q) The background terrain is depicted as variable density dot patternsin green, yellow, or red. The density and colour being a function ofhow close the terrain is relative to aircraft altitude. Terrain Alertsare depicted by painting the threatening terrain as solid yellowor red.

r) The set of Digital Elevation Matrix Overlays is processed by theterrain display algorithms into a matching set of Display MatrixOverlays and passed to the Radar Display Output Processor. TheDisplay Matrix Overlays hold display attributes rather thanelevation for each matrix element. These attributes are computedfor the background and terrain threat areas and minimized (onebyte) to reduce memory requirements and transfer time to theRadar Display Output Processor. The Aircraft Position andAircraft Heading are used at the Radar Display Output Processor toextract the radar-like sweeping image ahead of the aircraft from thedisplay overlays.

s) Each element of the output Display Matrix Overlays holds a singledisplay attribute bytes with fields for the colours, patterns, andsymbols.

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t) The EGPWS computer outputs a display of terrain data in weatherradar format, per ARINC-708/708A (ARINC 453) busspecification. The terrain data is displayed on the EFIS EHSIs.When the Terrain Display is activated, it replaces the WeatherRadar screen of the EHSI.

u) The Terrain Display can be made available to the flight crew atanytime. When the conditions for either a Terrain Caution or aTerrain Warning are detected, the EGPWS computer also suppliesa discrete “pop-up” signal. The “pop-up” signal is used to switchthe EHSI displays from the Weather Radar to the Terrain Display.

v) The Background Display is computed from the Aircraft Altitudewith respect to the terrain data in the Digital Elevation MatrixOverlays. Where terrain data are available and sufficiently close tothe Aircraft Altitude, they are presented in Background Colour dotpatterns reflecting the projected separations. Different dot densitypatterns and colours are used to represent terrain altitude bandswith respect to the aircraft. Areas with no terrain data available arepainted with the Low Density magenta dot Pattern.

w) The “Peaks” Mode terrain display allows terrain below the aircraftto be viewed on the EGPWS terrain display during the cruiseportion of flight. At altitudes safely above all terrain for the displayrange chosen, the terrain is displayed independent of aircraftaltitude emphasizing the highest and lowest elevations to provideincreased situational awareness. This increased awareness can beparticularly valuable to the flight crew in the event of an unplanneddescent or off-route deviation and for the purpose of previewingterrain prior to descent.

x) With the display, two elevation numbers indicating the highest andlowest terrain currently being displayed are overlaid on thedisplay. The elevation numbers indicate terrain in hundreds of feetabove sea level (MSL). The terrain elevation numbers aredisplayed with the “highest” terrain number on top, and the“lowest” terrain number beneath it. The “highest” terrain numberis shown in the same colour as the highest terrain colour pattern onthe display, and the “lowest” terrain number is shown in the colourof the lowest terrain colour pattern shown on the display. A singleelevation number is displayed when the screen is all black as aresult of flying over water or relatively flat terrain where there isno appreciable difference in terrain elevations. The elevationnumbers on the display are an additional indication that the terraindisplay is selected.

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y) The Peaks Mode display adds a new solid green level to indicatethe highest, non-threatening terrain. The existing lower densitygreen display patterns now indicate mid and upper terrain in thedisplay area as well as terrain that is within 2000 feet below theaircraft. The red and yellow dot patterns are unchanged andcontinue to indicate terrain that is near or above the current altitudeof the aircraft. Solid yellow and red colours are unchanged andcontinue to indicate alert and warning areas relative to the flightpath of the aircraft. The Peaks Mode display is prioritized such thathigher level colours and densities override lower colour anddensities for maximum situational awareness of the mostsignificant terrain relative to the altitude and flight path of theaircraft.

Figure 20

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Figure 21

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Figure 22

11) GPWS – Non-Normal DisplaysGPWS Non-Normal Messages

These messages show on the EFIS EHSI to alert the flight crew ofGPWS non-normal conditions:• System alert messages• Range disagree messages

a) GPWS System Alert Messages

These messages show in amber on the left side of the EHSI:• TERR POS shows when the GPWS determines airplane

position data is not valid.• TERR OVRD shows when the terrain override switch on the

Capt’s panel is pushed.• TERR FAIL shows when a fault occurs in the GPWS.

Terrain data does not show on either EHSI if there is a system alertmessage.

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b) Range Disagree Messages

These alert messages show in amber on the EHSI when there is arange disagree fault:

• TERR RANGE DISAGREE shows when the GPWS rangedisagrees with the range selected on the on-side EFIS controlpanel.

• MAP/TERR RANGE DISAGREE shows when the GPWSrange, the on-side EFIS range, and the FMC range disagree.

Terrain data does not show on the EHSI if there is a range disagreemessage.

Figure 23

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12) EGPWS/EFIS Interface

Until the advent of Enhanced GPWS, pressing a “WX” button to “ON”on an EFIS Control Panel would provide a ground which, via the WXRControl Panel would energise the Power Supply of the WXR R/T. Itwould also signal the respective EFIS to display the radar image at theselected range.

After installation of Enhanced GPWS, pressing the button, nowlabelled “WXR/TERR”, will still signal EFIS to display whicheverdata is at its ARInc 453 input port, be it Radar or Terrain.

With a pilot’s “WXR/TERR” button “ON”, momentarily pressing his“WXR” switch will power the Radar and give him a Radar image onEFIS, via a relaxed relay, and illuminate his “WXR” switch “ON”.

With his “WXR/TERR” button “ON”, momentarily pressing his“TERR” switch will trigger the GPWS Computer to energise hisTerrain Display Relay. This will:

• cause his “TERR” switch to illuminate “ON” and his “WXR”switch to extinguish.

• disconnect his power control of the Weather Radar R/T.

• changeover the very high speed ARInc 453 port of his EFISSymbol Generator from the Weather Radar R/T to the GPWSComputer for terrain display on the EHSI.

Unguarding and pressing the Capt’s “TERR OVRD” switchilluminates its “OVRD” light and inhibits the operation of Terraindisplay.

If the EGPWS System becomes unserviceable or loses positionaccuracy, the “TERR OVRD” switch “INOP” light illuminates.

DC power for the relays is from the No.1 Electronics bus via C/B“TERRAIN DISPLAY”.

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Figure 24

13) System self-test may be initiated by pressing the SYS TEST switch onthe EGPWS control module. Two types of self-test are available, aconfidence test and a full vocabulary test. The confidence test may beinitiated either on the ground or in the air (inhibited between lift offand 1000 feet radio altitude) to give the pilots an indication of systemoperation. The full vocabulary test, which may be initiated only on theground, is used as an operational test of the system.

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B. GROUND PROXIMITY SYSTEM - TROUBLE SHOOTING

(1) General

(a) Overview

The EGPWC contains extensive Built In Test or BIT capability. The BITfunctions provide high confidence that the Warning Computer andinterface signal sources are operating properly and that the EGPWS willperform its intended function. Detected failures are indicated via theGPWS INOP, Windshear INOP and Terrain INOP lights and by theARINC 429 output. Failures detected during flight are saved in the flighthistory and are annunciated during Level 4 of the cockpit self test. BITstatus is also available through the RS-232 port by use of a PC, terminal orduring ATP.

(b) Status LED’s

If the EGPWC detects an internal Warning Computer fault, it will turn onan INOP light. If the EGPWC detects an external input fault, it may or maynot turn on the INOP light(s) depending on the input fault, the type ofinstallation and whether the aircraft is airborne or on the ground.

(c) EGPWC BIT

The EGPWC BIT is comprised of three types of functions: OperationMonitoring, Operational Tests, and Restricted Tests.

1) Operation Monitoring

Operation Monitoring consists of software checks that are performedas part of the normal Warning Computer processing. OperationalMonitoring includes checks of data values and program flow controlvariables used for the warning computations to ensure they are withinexpected ranges. The status of various EGPWC hardware sub-systemsis continuously verified and includes core processor checks, voicegenerator circuitry checks and ARINC 429 wrap-around tests.Operational Monitoring also includes extensive testing of the inputsignals to ensure the EGPWC is using proper data for its calculations.

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2) Operation Tests

Operation Tests are run during normal operation and do not disrupt theEGPWC warning calculations or annunciations. Operations Testsinclude CPU instruction set tests, A/D tolerance tests, ROM check-sumverification tests and non-destructive RAM tests. Operation Tests arescheduled by the operating system to be performed between theroutines required for normal operation.

3) Restricted Tests

Restricted Tests destroy data or take an excessive amount of time tocomplete and cannot be used during normal system operation. Thesetests are usually run during system power up or during a cockpitinitiated self test. These tests primarily consist of more thoroughhardware checks that would disrupt normal operation if continuouslyrun.

(d) EGPWC Front Panel

1) To aid in troubleshooting the EGPWC, the front panel of the WarningComputer contains EGPWS Status LEDs, a Self Test interface, aPCMCIA interface, and a test plug.

(e) EGPWS Status LEDs

1) The EGPWC front panel Status LEDs consist of three LEDs – a yellowExternal Fault LED, a green Computer OK LED and a red ComputerFail LED. The yellow External Fault LED indicates that a faultexternal to the EGPWC exists. All external faults should be fixed priorto removing and replacing the EGPWC. The green Computer OK LEDindicates that the EGPWC is operating correctly with no internal faults.The red Computer Fail LED indicates that the EGPWC has an internalfault.

(f) Self Test Interface

1) The EGPWC front panel self test interface consists of a self test switchand a headphone jack which can be used to activate all of the self testfeatures. The front panel audio jack is a standard 600Ω monophonicaudio output compatible with a standard 2-connector 1/4” audio plugheadphones.

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(g) Front Panel PCMCIA Interface

1) The EGPWC front panel PCMCIA interface allows data upload anddownload capabilities. Instructions on the use of the PCMCIAinterface will be supplied in the Service Bulletin accompanying thesoftware update.

(h) Front Panel Test Plug (RS-232 Port)

1) The EGPWC front panel test plug (RS-232 port) provides variouscommunications support capabilities, discretes used for filedownloading and power outputs for a portable dataloader. This portserves as access to signal monitoring, flight history, initiating BITEtests, updating databases and other functions. The interface is fullduplex and is intended for human interaction, but can also be used forcustom interface programs such as the AlliedSignal VIEWS© utility.Its purpose is mainly for AlliedSignal Maintenance and EngineeringPersonnel.

(i) The procedures that follow assume that all the wiring is OK.

If the corrective action does not correct the failure, use the appropriatewiring diagram to make sure all wiring and connections are correct.

(2) “TERRAIN INOP” Light

(a) The “TERRAIN INOP” light on the Captains P1-3 panel indicates theserviceability of the Terrain (Enhanced) functions of the Enhanced GroundProximity Warning System.

(b) Under normal pre-flight conditions1 the “TERRAIN INOP” light willextinguish within 30 seconds after IRS-L or IRS-R switch is selected to“NAV”.

NOTE: Do not cycle power or replace the EGPWS computer untilLevel 1 and Level 2 self-tests have been performed.

(c) If the GPWS circuit breaker is cycled (or electrical power is interrupted)under normal pre-flight conditions (with all required inputs operating andthe aircraft in an open position) the “TERRAIN INOP” will remainilluminated for up to five (5) minutes.

1. “normal pre-flight conditions”: all required inputs operating and the aircraft in an open position with clear view of GPS satellites.

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(d) If the EGPWS Computer is replaced, the “TERRAIN INOP” light mayremain illuminated for up to twenty (20) minutes after power is applied.

(e) Level 1 And 2 Self Tests:

1) The Level 1 Self Test will give the message “Internal GPS NotNavigating” if the internal GPS card is still trying to acquire the GPSsatellites (after application of power or a power cycle), and will alsoindicate which of the GPWS modes is/are inoperative.

2) The Level 2 Self-test will indicate any internal computer faults, andalso which external inputs, if any, are causing the any of the EHSImessages be displayed or the “TERRAIN INOP” light to beilluminated.

3) The Level 2 Self test will also give the message “Internal GPS Failed”if the GPS card has been unable to acquire the GPS satellites for anextended period, for example when an aircraft is located inside ahangar. This is not a hardware failure – do not replace the EGPWScomputer.

(f) Required Inputs

1) The Terrain function requires much input from many external systemsand the “TERR INOP” light will be illuminated unless the minimumrequired inputs are received. Note however that where external inputsare duplicated for redundancy, input from only one source of thatsystem is required. The minimum required inputs are: • LRRA #1 or #2 Radio Altitude • FMC #1 Lat, Long, Heading • ADC #1 Altitude, Altitude Rate, Airspeed, SAT • VHF NAV #1 or #2 Glideslope & Localiser Deviation • IRS #1 or #2 Pitch & Roll, Body Acceleration,

True Heading • EFIS C/P #1 or #2 WXR on/off, EHSI Display mode

and range • DSWC #1 or #2AOA & Flap Angle

(where windshear activated) • DAA #1 or #2

2) The EGPWS computer on these aircraft contains an internal GPS card,used to determine aircraft position to the high level of accuracyrequired for the EGPWS predictive terrain function. The “TERRAININOP” light will be illuminated when the GPS card is not providing therequired position data.

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(g) GPS Satellite Acquisition

1) After Applying electrical power to an existing EGPWS computer, oreven after a short power interrupt like cycling the circuit breaker, andwith the aircraft in an open position in clear view of the GPS satellites,the internal GPS card may take up to five (5) minutes to re-acquire theGPS satellites and commence sending position data to the terrainfunction of the unit.

2) After installation of a replacement EGPWS computer, and with theaircraft in an open position in clear view of the GPS satellites, theinternal GPS card may take up to twenty (20) minutes to re-acquirethe GPS satellites and commence sending position data to the terrainfunction of the unit.

3) During this GPS satellite acquisition time, the “TERRAIN INOP” lightwill be illuminated. Only after this period will the “TERRAIN INOP”light extinguish (provided all other required inputs as indicated aboveare received as well).

4) The GPS satellite acquisition time will increase if the view of GPSsatellites is partially obstructed by any building or structure. Note thatthe GPS antenna is located on the aircraft fuselage crown at STA500A.

5) If the view of GPS satellites is substantially or wholly obstructed, forexample due to the aircraft being located inside a hangar, the internalGPS card will not be able to acquire any satellites and the TerrainINOP light will remain illuminated.

6) If the view of GPS satellites is substantially or wholly obstructed for anextended period, the Level 2 Self Test will report “GPWS ComputerOK” and “Internal GPS Failed”. This is not a hardware failure but anindication that the internal GPS card is unable to acquire any satellites.Do not replace the EGPWS computer in this case.

(3) EFIS EHSI “GND PROX SYS” Message

(a) The EFIS EHSI “GND PROX SYS” message indicates serviceability of thebasic GPWS Modes 1-4 terrain clearance, mode 5 Glideslope and mode 6Altitude Callouts.

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(4) EFIS EHSI “WINDSHEAR SYS” or “WINDSHEAR REAC” message.

(a) The EFIS EHSI “WINDSHEAR SYS” or “WINDSHEAR REAC”message indicates serviceability of the GPWS Reactive Windshearwarning Mode 7 (where fitted).

(5) Prepare For Trouble-Shooting

(a) Make sure that the following circuit breakers are closed:

NOTE: If a circuit breaker cannot be (or is not) closed, a failure indicationwill be given for the related system.

(b) Flaps, Landing Gear Position

Make sure that the flaps are up, and that the landing gear lever is in theOFF or DN position.

P18 P6

GND PROX WARN STALL WARN

RADIO ALTM-1 RADIO ALTM 2

VHF NAV-1 (VOR/ILS) VHF NAV-2

No. 1 AIR DATA No. 2 AIR DATA

DAA NO. 1 DAA No. 2

IRS NO. 1 IRS No. 2

STALL WARN STALL WARNING SYS 2

DAA FMC NO. 1 DAA FMC No. 2

EFIS EFIS

FMCS

TERRAIN DISPLAY

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(c) Apply Electrical Power

Do this task to apply electrical power: “Manual Control” (AMM24-22-00/201).

(d) ILS Frequency

Set an ILS frequency on VHF NAV-1 (AMM 34-31-02/501).

(e) Warning Flags

Make sure that the failure warning flag in the captain’s height indicator andaltimeter are not in view.

(f) VHF NAV Transfer Switch

Make sure that the VHF NAV transfer switch is set at the NORMALposition.

(g) Glideslope Flag

Make sure that the GS flag on captain's ADI is out of view.

(6) Self Test Function

The EGPWC support a cockpit operated self test sequence that indicates theoperational status of the system. The self test aurals annunciate the status of themajor functions of the system: Glideslope, GPWS, Bank Angle, AltitudeCallouts, Windshear Detection and Terrain Awareness and activates the outputs(lights and displays) for visual verification. The EGPWC self test also providesmaintenance information detailing the cause of detected faults, historicalinformation of faults and warnings occurring during flight, and EGPWC andinstallation configuration information. The self test aurals will be heard in thecockpit and through the headphone jack on the EGPWC front panel.

The EGPWC self test is divided into six levels:

Level 1 – Enunciates the current status of each of the major functions of theEGPWS. This is the normal pre-takeoff test performed by the flight crew. Thislevel can be initiated both on the ground and during flight above 2000 feet ofradio altitude.

Level 2 – Identifies all failures currently within the system. Level 2 is accessedby maintenance personnel to help resolve INOP conditions. Level 2 can only beaccessed on the ground.

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Level 3 – Identifies the configuration status of the Warning Computer and theinstallation. Level 3 can only be accessed on the ground.

Level 4 – Enunciates faults that have occurred during past flights. Thisinformation can be used to resolve system problems reported by the flightcrews. Level 4 can only be accessed on the ground.

Level 5 – Enunciates warnings that have occurred during past flights. Thisinformation can be used to resolve system problems reported by the flightcrews. Level 5 can only be accessed on the ground.

Level 6 – Enunciates state changes in the input discretes. This information canbe used to verify the installation and operation of the discrete inputs. Level 6can only be accessed on the ground.

The following sections detail the operation of each self test level.

NOTE: In the following sections reference is made to a “short cancel” and a“long cancel”. A “short cancel” is defined as depressing the self testswitch (either in the cockpit or on the EGPWC front panel) for lessthan 2 seconds. A “long cancel” is defined as depressing the self testswitch for more than 2 seconds.

(a) Self Test Level 1

Level 1 testing enunciates the current status of each of the major functionsof the EGPWS: descent below glideslope, GPWS, bank angle protection,altitude callouts, windshear detection, and terrain awareness. The Level 1self test is comprised of three parts: preamble, short test and long test.

The preamble and short test portions of the Level 1 test is initiated bymomentarily pressing the EGPWS test switch. The long test portion isinitiated by depressing the EGPWS test switch for a period between 2 and 5seconds. The Level 1 test can only be initiated when the aircraft is on theground or if radio altitude is greater than 2000 feet.

All interfacing systems should be powered on and operating prior toconducting a Level 1 self test.

The Terrain Display must be placed in a mode which will allow the terraindisplay to be shown (e.g. Map mode) prior to starting the test in order to seethe Terrain Display test pattern, requiring the selection of “WXR/TERR”prior to starting the test. The WXR may be placed in TEST mode.

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1) Preamble

The preamble checks the program pin connections and the internalmemory prior to starting the self test. If any faults are detected, the selftest will enunciate the detected fault and terminate the self test process.

2) Short Test

Upon completion of the preamble, the short self test is started. Thenormal Level 1 short self test sequence is as follows:

a) Self Test button pressed and released

b) GPWS INOP, Terrain INOP, lights turn on

c) Glideslope lights turn on

d) Voice: “GLIDESLOPE”

e) Glideslope lights turn off

f) GPWS PULL UP lights turns on

g) Voice: “PULL UP”

h) GPWS PULL UP lights turn off

i) Windshear Warn lights turn on

j) Voice: “(SIREN) WINDSHEAR, WINDSHEAR, WINDSHEAR”

k) Windshear Warn light turns off

l) Terrain Displays show terrain test pattern

m) Voice: “TERRAIN TERRAIN PULL UP”

n) Terrain Displays return to normal

o) All INOP lights turn off

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3) Long Test

The long self test enunciates all activated alert voices, includingwarning, caution and altitude callout voices.

a) Maintenance Action

The Level 1 self test will detect and annunciate any current failureconditions which effect the operation of the major EGPWCfunctions. The following tables identify the response for the faultsannunciated during the self test.

Voice ResponseProgram Pin Parity Error Probable error in wiring for the program pins.

Verify the program pins are wired correctly and configure the parity pin for ODD parity.

Aircraft Configuration Data Base CRC Failed

Remove and replace EGPWC.

Aircraft Configuration Data Base Failed

Remove and replace EGPWC.

Aircraft Type Invalid Probable error in aircraft type program pins. Verify the aircraft type program pin connection.

Glideslope INOP Perform a Level 2 self test to troubleshoot the problem.

GPWS INOP Perform a Level 2 self test to troubleshoot the problem.

Bank Angle INOP Perform a Level 2 self test to troubleshoot the problem.

Callouts INOP Perform a Level 2 self test to troubleshoot the problem.

Windshear INOP Perform a Level 2 self test to troubleshoot the problem.

Terrain INOP Perform a Level 2 self test to troubleshoot the problem.

Only response in aural “GPWS Inhibited – Terrain Inhibited”

Indicates that a “Audio Inhibit” input to the EGPWC is selected

Only response is aural “GPWS Inhibited”

Indicates that a “GPWS Inhibit” input to the EGPWC is selected.

Response includes aural “Terrain Inhibited”

Indicates that the “Terrain Awareness and TCF Inhibit” input to the EGPWC is selected.

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b) Self Test Level 2

A Level 2 self-test tells the maintenance crew if there are any faultscurrently in the system.

Level 2 is accessed while the aircraft is on the ground by pressingthe EGPWS test switch within 3 seconds of the end of the Level 1test or a short cancel during a Level 1 self test. The message“CURRENT FAULTS” will be enunciated when Level 2 starts.The Level 2 test is not accessible while airborne.

During the Level 2 self test a short or a long cancel terminates theself-test and “PRESS TO CONTINUE” is enunciated forproceeding to Level 3 self test.

If no faults currently exist the message “NO FAULTS” will beenunciated.

If a fault is detected, it will be classified as either an internal orexternal fault. Internal faults are defined as those faults thatoriginate within the EGPWC. Internal faults will turn on the redCOMPUTER FAIL LED on the EGPWC front panel. Externalfaults are defined as those faults that originate from sources outsidethe EGPWC. External faults will turn on the amber EXTERNALFAULT LED on the EGPWC front panel.

An internal fault indicates a problem with the Warning Computer.The system should be checked and the Warning Computer shouldbe removed and replaced if required. The following figure lists theinternal faults messages and the probable maintenance response.

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ARINC 429 bus activity, ARINC 429 signal faults, input discretemonitoring, analog input wire monitoring and analog signal faultsare categorized as external faults. The following figure list thetypes of messages and the probable maintenance response requiredfor an external fault.

Level 2 Self Test Annunciation – Internal Faults

Annunciation: ROM FAILED

RAM FAILED

NVM RAM FAILED

NVM FAILED

WATCHDOG TIMER FAILED

EXCESSIVE WATCHDOG TIMEOUTS FAILURE

ANALOG CONVERTER FAILED

VOICE GENERATOR FAILED

ARINC 429 TRANSMITTER FAILED

ARINC 429 RECEIVER FAILED

APPLICATION DATABASE FAILED

APPLICATION DATABASE CRC FAILED

TERRAIN DATABASE FAILED

ENVELOPE MODULATION DATABASE FAILED

CONFIGURATION DATABASE FAILED

SYSTEM OR MODE TASK FAILED

SUPPORT TASK FAILED

Probable Cause: EGPWC failure

Action: Remove and replace the EGPWC.

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Level 2 Self Test Annunciation – External FaultsAnnunciation InactiveExample: GPS BUS 1 InactiveProbable Cause: Input source is not powered or a wiring problem exists between the

source LRU and the Warning ComputerAction: Verify input source LRU is powered.

Verify wiring from source to LRU.Annunciation FAULTExample: ILS BUS 1 GLIDESLOPE FAULTProbable Cause: Input signal SSM = Fail Warning, or

Input signal is not being transmitted (incorrect update rate).Action: Repair input signal.Annunciation WIRING FAULTExample: RADIO ALTIMETER 1 WIRING FAULTProbable Cause: Open wire monitor has detected no connection from the SOURCE LRU.Action: Verify wiring from the source LRU.Annunciation FLAP SWITCH FAULTProbable Cause: Electrical short at the flap discrete input.Action: Verify wiring from the flap override switch and/or flap input discretes.Annunciation GEAR SWITCH FAULTProbable Cause: Electrical short at the gear discrete input.Action: Verify wiring from the gear override switch and/or gear input discrete.Annunciation AUDIO CANCEL INVALIDProbable Cause: Electrical short at the audio cancel input.Action: Verify wiring from the audio cancel switch.Annunciation ALL MODES INHIBIT INVALIDProbable Cause: Electrical short at the audio cancel input.Action: Verify wiring from the audio cancel invalid.Annunciation GLIDESLOPE CANCEL INVALIDProbable Cause: Electrical short at the glideslope cancel input.Action: Verify wiring from the glideslope cancel input.Annunciation ILS SELECT INVALIDProbable Cause: Electrical short at the ILS Select inputs.Action: Verify wiring from the ILS Select inputs.

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Annunciation FLAP ANGLE UNREASONABLEProbable Cause: Electrical short at the flap discrete input(s).Action: Verify wiring from the flap input discrete(s).Annunciation SELF TEST INVALIDProbable Cause: Electrical short at the self test input.Action: Verify wiring from the self test discrete.Annunciation MOMENTARY TERRAIN SELECT 1 (OR 2) INVALIDProbable Cause: Electrical short at the Terrain Select input(s).Action: Verify wiring from the terrain “ON” switches.Annunciation PROGRAM PIN READ ERRORProbable Cause: Wiring error to the program pins.Action: Verify wiring to each program pin.Annunciation PROGRAM PIN PARITY ERRORProbable Cause: Wiring error to the program pins.Action: Verify wiring to each program pin. Verify ODD parity selected.Annunciation AIRCRAFT TYPE INVALIDProbable Cause: Wiring error to the Aircraft Type program pins.Action: Verify wiring to the Aircraft Type program pins.Annunciation CALLOUTS OPTION INVALIDProbable Cause: Wiring error to the callouts options program pins.Action: Verify wiring to the Callouts Options program pins.Annunciation AUDIO MENU INVALIDProbable Cause: Wiring error to the Audio Menu program pins.Action: Verify wiring to the Audio Menu program pins.Annunciation PROGRAM PIN INVALID (where XX is a number)Probable Cause: Invalid option selected.Action: Verify wiring to all program pins.

Level 2 Self Test Annunciation – External Faults

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For example, if the computed airspeed on air data computer 1 isfailed (SSM = Fail Warning) the following messages would beannunciated:

“CURRENT FAULTS”“EGPWC OK”“EXTERNAL FAULTS”“AIR DATA BUS 1 COMPUTED AIRSPEED FAULT”“PRESS TO CONTINUE”

c) Self Test Level 3

A Level 3 self test enunciates Warning Computer configurationinformation. This information is determined by the wiring of theprogram pins, from data stored in the computer ROM and byidentification resistors on each of the internal circuit boards.

Level 3 is accessed while the aircraft is on the ground by pressingthe EGPWS test switch within 3 seconds of the “PRESS TOCONTINUE” message at the end of the Level 2 test. The message“SYSTEM CONFIGURATION” will be enunciated when Level 3starts.

During a Level 3 self test a short cancel bumps the enunciation tothe next Level 3 item (e.g. from terrain database information toenvelope modulation database information). A long cancelterminates the self-test level and “PRESS TO CONTINUE” isenunciated for proceeding to Level 4 self test.

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The following information is given in the Level 3 self test:

1. EGPWC Part Number

2. EGPWC Mod Status

3. EGPWC Serial Number

4. Application Software Number

5. Configuration Software Version

6. Terrain Database Version

7. Envelope Modulation Database Version

8. Boot Code Version

9. Aircraft Type

10. Audio menu

11. Altitude Callout Menu

All other selected program pin options (e.g. triple radio altimeters).Note that only those features that are enabled or disabled from thebasic configuration are enunciated.

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d) Self Test Level 4

A Level 4 self-test enunciates the faults recorded over the last 10flight legs.

A Level 4 self test can only be accessed on the ground by pressingthe EGPWS test switch within 3 seconds of the “PRESS TOCONTINUE” message at the end of Level 3. The message “FaultHistory” is enunciated when Level 4 starts.

During a Level 4 self test, a short cancel bumps to the next flightleg with faults (if any). A long cancel will terminate the self testlevel and “PRESS TO CONTINUE” will be enunciated forproceeding to Level 5 self test.

If no faults occurred within the previous 10 flight legs the message“NO FAULTS” will be given. If a fault occurred within theprevious 10 flight legs the aural messages enunciated will be thesame as given in Level 2 with the added information of whichflight leg the fault occurred. For example, if radio altimeter bus 1failed 4 flights earlier the messages would be:

1. “FLIGHT 4”

2. “EGPWC OK”

3. “EXTERNAL FAULTS”

4. “RADIO ALTIMETER BUS 1 INACTIVE”

5. “PRESS TO CONTINUE”

Note that flight 1 was the most recent flight.

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e) Self Test Level 5

A Level 5 self-test enunciates all the alerts (cautions and warnings)recorded over the last 10 flight legs.

A Level 5 self test can only be accessed on the ground by pressingthe EGPWS test switch within 3 seconds of the “PRESS TOCONTINUE” message at the end of Level 4. The message“WARNING HISTORY” is enunciated when Level 5 starts.

During a Level 5 self test performing a short cancel bumps to thenext flight leg with warnings (if any). A long cancel will terminatethe self test level and “PRESS TO CONTINUE” will beenunciated for proceeding to Level 6 self test.

If no alerts were issued within the previous 10 flight legs themessage “NO WARNINGS” will be enunciated. If an alert wasgiven within the last 10 flight legs the flight leg and alert messagewill be enunciated.

For example, if a glideslope alert was given 7 flight legs earlier themessages would be:

1. “WARNING HISTORY”

2. “FLIGHT 7”

3. “GLIDESLOPE”

4. “PRESS TO CONTINUE”

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f) Self Test Level 6

A Level 6 self-test enunciates any change in status of the discreteinputs for the selected aircraft type. This feature is provided forproduction aircraft testing of the discrete input wiring and isintended to match the maintenance display feature provided on theMK V front panel display.

A Level 6 self-test can only be accessed on the ground by pressingthe EGPWS test switch within 3 seconds of the “PRESS TOCONTINUE” message at the end of Level 5. The message“DISCRETE INPUT TEST, PRESS TO CANCEL” is enunciatedwhen Level 6 starts and will be repeated approximately every 60seconds until the test is terminated.

A short or long cancel will terminate the self test level and themessage “END OF SELF TEST” will be enunciated.

The Level 6 self-test monitors each input discrete for a statechange. If a state change occurs, the EGPWC will enunciate thefunctional name of the discrete followed by its new state. Forexample if the Glideslope Cancel discrete input is defined as GND= CANCEL, and the discrete transitions from OPEN to GND, themessage “GLIDESLOPE CANCELLED” will be issued. If theinput is reset (transitions from GND to OPEN), the message“GLIDESLOPE ENABLED” will be issued.

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The following table defines the audio phrase for each inputdiscrete. Note that not all of the discretes are used on all aircraft.The self-test discrete cannot be tested in a Level 6 self test.

DISCRETE NAME STATE => AUDIO PHRASE

Display Select Discrete #1 True =>False =>

Display Discrete 1 TrueDisplay Discrete 1 False

Display Select Discrete #2 True =>False =>

Display Discrete 2 TrueDisplay Discrete 2 False

Landing Flaps Discrete or Flap Override

Selected =>Not Selected =>

Landing FlapsNot Landing Flaps

Flap Position Discrete #1 Selected =>Not Selected =>

Flap 1 TrueFlap 1 False

Landing Gear Discrete Selected =>Not Selected =>

Landing Gear DownLanding Gear Up

Radio Altitude Validity Discrete #1 Valid =>Invalid =>

Radio Altimeter 1 ValidRadio Altimeter 1 Invalid

Radio Altitude Validity Discrete #2 Valid =>Invalid =>

Radio Altimeter 2 ValidRadio Altimeter 2 Invalid

Glideslope Validity Discrete #1 Valid =>Invalid =>

Glideslope 1 ValidGlideslope 1 invalid

Glideslope Validity Discrete #2 Valid =>Invalid =>

Glideslope 2 ValidGlideslope 2 invalid

ILS Tuned Discrete #1 ILS Tuned =>ILS not Tuned =>

ILS 1 TunedILS 1 not Tuned

ILS Tuned Discrete #2 ILS Tuned =>ILS not Tuned =>

ILS 2 TunedILS 2 Not Tuned

AOA/SWC Validity Discrete #1 Valid =>Invalid =>

AOA 1 ValidAOA 1 Invalid

AOA/SWC Validity Discrete #2 Valid =>Invalid =>

AOA 2 ValidAOA 2 Invalid

Air/Ground Discrete In Air =>On Ground =>

Not On GroundOn Ground

Glideslope Inhibit Discrete Inhibit =>Not Inhibit =>

Glideslope Inhibit TrueGlideslope Inhibit False

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Mode 6 Low Volume Discrete Low Volume =>Normal =>

Mode 6 Low VolumeMode 6 Normal Volume

DH Discrete >DH =>

Below DHAbove DH

Audio Inhibit Discrete GPWS Inhibit =>Not Inhibit =>

Audio InhibitAudio Not Inhibit

Altitude Callouts Enable Discrete Voice Enable =>Voice Disabled =>

Callouts EnabledCallouts Disabled

Momentary Audio Suppress Discrete

Audio Suppress =>Normal =>

Audio InhibitAudio Not Inhibit

Self Test Discrete N/A N/AGlideslope Cancel Discrete Cancel =>

Normal =>Glideslope CancelledGlideslope Enabled

ILS Bus Select Discrete #1 Selected =>Not Selected =>

ILS Select 1 TrueILS Select 1 False

Steep Approach Discrete #1 Enabled =>Disabled =>

Steep Approach EnabledSteep Approach Disabled

ILS (vs. MLS) Selected Discrete ILS Selected =>MLS Selected =>

ILS SelectedMLS Selected

WXR on Discrete On =>Off =>

Weather OnWeather Off

Simulator Reposition Discrete Reposition =>Normal =>

Simulator Reposition OnSimulator Reposition Off

EFIS Range On =>Off =>

Range 1 (2,3,4) OnRange 1 (2,3,4) Off

Terrain Awareness and TCF Inhibit Disabled =>Normal =>

Terrain OffTerrain On

PWS Interlock #1 On =>Off =>

PWS Discrete 1 OnPWS Discrete 1 Off

GPWS Inhibit On =>Off =>

GPWS InhibitGPWS Not Inhibit

DISCRETE NAME STATE => AUDIO PHRASE

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(7) General Troubleshooting Guide

(a) Recommended Maintenance Response To Status Led’s

In general, if the GPWS INOP light is ON, the EGPWC front panel LEDsshould be checked. The following table shows the recommendedmaintenance action in response to the front panel LEDs.

A Terrain INOP light may not always imply an external or internal failureof the EGPWC. The Terrain INOP light may turn on if the requiredaccuracy of the position information is not being received from the GPS,IRS or the FMC. Therefore, if the Terrain INOP light is reported to be on orwas on, perform a Level 2 self test. If no faults are present, verify theposition data from the GPS, IRS and FMC are correct.

External Fault

Documents

Q72-34-015 r004 · BOEING 737-300/400/500 Q72-34-015 Page 1 of 98 Q72 - MAINTENANCE INSTRUCTION QANTAS AIRCRAFT MAINTENANCE MANUAL CHAPTER 34 EFFECTIVITY VH-TJE thru VH-TJU, VH-TJW,