B777 VHF Communication Systems

VHF System

• VHF frequency can be tuned using VHF Left on RTP L/C/R or any RTP.
• B777 VHF systems have 3 system/xcvrs located in E1 and E2 racks.
• SELCAL calls can be received through the SELCAL decoder via VHF and HF systems.
• A SELCAL call triggers an EICAS message, HI-LO chime, and CALL light in the ACP.
• The WES system controls the HI-LO chime for SELCAL.
• A call in the SELCAL using VHF Left activates ALL ACP VHF call lights.
• VHF C or R can be used for data communication, with VHF C having priority, followed by SATCOM and VHF R.
• When tuning in VHF L using RTP C, the offside light lamp turns on in the RTPs L and C.
• The offside tuning light indicates tuning offside XCVR or others attempting to tune onside XCVR.
• The purpose of HF sense is to filter background noise.
• When transmitting with VHF systems, sidetone indicates sufficient power.
• PANEL FAIL in RTP means RTP fault, while DASHES indicate XCVRS fault.
• In the RTP, selecting a frequency for the HF system puts you in home/homing mode.
• To enter tuning and operate mode for the HF system, press PTT once for tuning mode, and a second time for operate or transmit mode.
• HF/VHF system can be tested at MAT, and OPC completes the test.
• Transmission in HF Left is not possible while using HF Right due to key interlock relay.
• When MAT is inoperative, VHF/HF system can be bite tested from the unit's front panel.
• A red KEY INTERLOCK light on the HF unit's front panel signals a faulty HF coupler.
• A red CONTROL light indicates a faulty RTP controlling the unit, while a red LRU light indicates a fault in the XCVR itself.

HF System

• HF systems components include 2 HF xcvrs, 2 HF couplers, and 1 HF antenna.
• HF xcvrs are located in the E6 rack in the aft cargo.
• HF coupler gets its supply from the HF XCVR.
• HF XCVR is supplied with 115V AC 3-phase.

SATCOM

• SATCOM provides voice and data communication.
• The BSU controls the point of the SATCOM antenna.
• SATCOM system can be used when ADIRU is in full alignment.

Flight Deck Communication

• The Center CDU or Handset is used to call the mechanic on the ground from the flight deck.
• Ground mechanic receives a 3-second mech horn when the flight deck calls.
• A continuous horn indicates ADIRU on BATT and Equipment Cooling failure.
• To talk to mechanic on the APU from the flight deck, switch on the svc interphone switch located in P5.
• Indications in the flight deck when the mechanic on the ground call include an Eicas message, Chime, and ACP call light.
• The INT toggle switch in the ACP is used to talk to the mechanic on the ground from the flight deck.

AMU

• B777 has 1 AMU with 3 station cards.
• The observer audio selector switch located in the P8 is used to switch AMU station cards in case of failure.

Power Supply

• When the primary external power is on, the GH bus is supplied.
• YES, the svc interphone system is supplied when the GH bus has supply.

RTP

• RTPs have crosstalk buses to make the display frequency the same when 2 RTPs use the same XCVR.

Observer Audio Selector Switch

• The observer selector switch sends a ground signal.

CVR

• With the optional auto-on switch, the CVR gets supply when the engine starts or the aircraft is in flight.
• The CVR records 4 channels.
• The pre-amplifier of the CVR is located in the CVR control panel.
• CVR recordings can be erased when parking brakes are on and the aircraft is on the ground by pressing the erase button on the CVR control panel for 2 seconds.

ARINC 629 Bus

• LRUs send information to the ARINC 629 bus periodically.

OPAS/OPCF/OPBC

• Discrete signals from the overhead panel in the flight deck go to the OPCF of OPAS.
• The signal from OPCF to OPBC is RS-485.

ELT

• The ELT sends data to the ground when the aircraft crashes.
• ELT gets its power from its own battery.
• The ELT has 3 frequencies and 1 antenna.
• The programmable switch module sends aircraft identification via the 406MHz frequency.
• The aircraft identification module interfaces between the programmable switch module and the ELT.
• Indications when the ELT has been activated include a status light on the unit, an advisory message in EICAS, and a signal tone in the 121.5MHz frequency.
• ELT can be switched on in the flight deck ELT control panel and in the front panel of the ELT.

Cabin System

• Quick tests and all tests are needed for the major components of cabin systems.
• Quick test is a continuous monitoring test.
• B777-300 has 4 ZMUs located in the cabin ceiling.
• Each zone has 3 columns of OEUs.
• Each zone has 1 column of SDMs.
• A maximum of 2 speakers can be connected per SDM.
• An ALL test makes the speakers operate at the same time.
• Direct access from DR4L has higher priority than the flight deck handset.
• PA/CI computer prioritizes the signal that goes to PA announcement.
• The ANS is tapped to SDM to measure background noise in order to increase the volume of the PA.
• The PA/CI has 4 channel and 4 power supply/ 4 CBs.
• PA/CI channels are PA normal, PA alternate, CI normal, CI alternate.
• The first line of troubleshooting for PAX AD in the EICAS is to switch PA alternate in the ASP.
• The signal from direct access directly goes to the PA part of the PA/CI controller.
• The direct access relay is located inside the ZMU.
• The intersystem bus connects the PA part of the PA/CI to the ZMU.
• The CI bus connects the CI part of the PA/CI to the ZMU.
• The wire that connects the CI part of the PA/CI to ZMU is the CI bus.
• The B777 has 7 ARINC 629 buses.

Pitot Static System

• The B777 has 3 pitot probes and 6 static ports.
• Pitot ADMs and SADMs are located between the FEC and MEC.
• Static ADMs and SADMs are located in the forward cargo ceiling.
• ADM gives ARINC 629 output, while SADM gives ARINC 429 output.
• ADM is software loadable.
• ADMs and SADMs are not interchangeable; only ADMs can be interchanged with other ADMs, and SADMs with SADMs.
• The center pitot probes and static ports are connected to the ISFD.
• The ISFD computes airspeed, attitude, and altitude information.
• Inertial sensors inside the ISFD compute or process attitude information.
• Magnetic heading and ground speed indication in the ISFD come from the Left AIMS.
• Localizer and glideslope information in ISFD comes from MMR C / ILS C.
• A functional and bite test of the ISFD is performed by pressing the APP and IN/HP pushbuttons for 2 seconds or in MAT for the bite test.
• SADM gets its power supply from the ADM power supply with 13.5V DC located in the P2 of the flight deck.
• Magnetic compass and compass card are located in the P5 panel for the compass and the center of windshield for the compass card.
• Non-magnetic tools should be used when removing or installing the compass.

ADIRU and SAARU

• The SAARU is located in the E2 rack, and the ADIRU in the E3 rack.
• A 1/4 hex/allen wrench is the special tool for removal and installation of ADIRU.
• ADIRU has 6 gyros and 6 accelerometers, while SAARU has 4 gyros and 4 accelerometers.
• ADIRU has 3 power supplies.
• ADIRU has 4 processors.
• When 1 gyro becomes inoperative in the ADIRU, a maintenance memo with maintenance message is generated.
• When 1 gyro and 2 accelerometers become inoperative in the ADIRU, a status message with maintenance message is generated.
• When 3 processors in the ADIRU become inoperative, a caution message and status message with maintenance message are generated.

GPS

• The B777 has 2 GPS systems included in MMR L/R.
• Latitude and longitude information of GPS can be seen on position init page 1/3.
• The GPS system can be deactivated on position ref page 2/3 or 3/3.
• The GPS system needs 4 satellites to track a moving object.
• In low satellite coverage, ADIRU can be used as the 4th satellite.
• ADIRU interfaces with the GPS system for fast alignment of ADIRU, in addition to functioning as the 4th satellite.
• The GPS system interfaces with the electronic flight bag for airport mapping.

ILS

• The B777 has 3 ILS systems inside of MMR and 4 antennas.
• The ILS uses the VOR antenna for localizer capture.
• A power divider is used to select whether the VOR antenna is used by the VOR or ILS system.
• The localizer antenna, glideslope capture antenna, and glideslope track antenna are located in the Nose radome for localizer and glideslope capture antennas and NLG door for glideslope track antenna.
• AIMS under AFDC controls and monitors the switching for the glideslope capture and track antennas.
• R AIMS under FMCF auto tunes the ILS system.
• The ILS system can be manually tuned in the L and R CDU in normal condition, or in the C CDU when other CDUs are inoperative.
• When FMCF L and R are inoperative, alternate tuning is used for the ILS system.
• The L CDU can alternate tune the ILS C and L.
• The L and R CDU are only for alternate tuning.
• ILS, VOR, DME, and ADF have 2 ports of tuning.
• The NAV RAD pushbutton in the CDU shows the page for tuning ILS, VOR, DME, and ADF systems.
• A frequency display of 114.50 A DEF in the CDU indicates auto tuning.
• ILS display is visible on the PFD and ND.
• ILS L is the primary source for the CAPT display, and ILS R for the F/O display.
• The LOC, ILS, and GLIDESLOPE flags will show in the display when there is a triple MMR inoperative.
• AFDC sends the tune inhibit signal to the ILS system.
• ILS L interfaces with GPWC for the mode 5 computation of GPWC.
• ILS C is connected to ISFD.

VOR

• The B777 has 2 VOR units and 1 antenna.
• The Marker Beacon is connected to VOR L only.
• The B777 has 1 marker beacon antenna located in the lower fuselage.
• Marker beacon information can be seen in the PFD.
• VOR information is visible on the ND.
• VOR pointer bearing can be seen in the ND in APP, VOR, and MAP selections.

ADF

• The ADF system has 2 units and 2 antennas.
• The ADF antenna assembly include 2 loop and 1 sense for 1 ADF antenna and located in the upper fuselage.
• The ADF system has no auto tuning function.
• The bearing pointer of ADF is visible on the ND.

DME

• The B777 has 2 DME interrogators and 2 antennas.
• The DME antenna is interchangeable with the ATC antenna.
• DME, ATC, and TCAS are connected to the suppression splitter.

RA (Radio Altimeter)

• The B777 has 3 RA transceivers and 6 antennas.
• The RA transceivers are located in the E5 rack of the fwd cargo and the antennas are located in the lower fuselage.
• RA L/C/R are connected to GPWC, RA L/R for WXR and TCAS system.
• RA is connected to TCAS for sensitivity level.
• RA is connected to WXR for predictive wind shear computation.
• The Decision Height (DH) for the RA can be set in the EFIS control panel and CDUs for alternate EFIS.
• The RA display is visible only in PFD.
• When the aircraft reaches the selected DH in the EFIS control panel, an amber indication appears in the PFD display with an aural sound.
• The priority for the RA indications in the PFD is RA L/C/R for the CAPT PFD and RA R/C/L for the F/O PFD.
• The function of the AID pin program of the RA system is to compensate the altitude calculation for antenna cable length and distance.

ATC (Air Traffic Control)

• The B777 has 2 ATC transponders and 2 ATC antennas.
• Either the left or right ATC transponder uses the ATC antennas, depending on which is selected in the transponder panel.
• The ATC coax relay serves as a switch for the L or R ATC transponder to use the antennas.
• Either the top or bottom ATC antenna is used for transmission, whichever has the strongest reception signal.
• The ATC system is powered when the ATC mode selector switch is in the standby position, but is not operational, only bite test is possible.

GPWC (Ground Proximity Warning Computer)

• The GPWC generates the radio callout in mode 6.

Weather Radar & TCAS

• Weather radar info is displayed in ND by switching it on in the EFIS control panel or CDUs for alternate.
• To display the terrain of GPWC, the weather radar, and TCAS symbols in the ND, select expanded app, expanded vor, expanded map, and centered map in the EFIS control panel.
• The B777 has 1 TCAS computer and 2 antennas.
• A cyan TFC message in the lower left of the ND indicates that the TFC switch is on.
• GPWC has priority over TCAS if both send a signal at the same time.
• Reactive wind shear of the GPWC is mode 7.
• Reactive wind shear generates an aural warning, a red message in the PFD, and an MWL.
• The B777 has 1 WXR antenna located in the nose radome.
• The WXR antenna will not operate during maintenance if the scan and elevation switch are in the disable position.
• The weather radar test pattern will not show due to WXR antenna failure, WXR LRU failure, and WXR control panel failure.
• GPWC Level 1 test can be done in MAT and in the LRU itself.
• The complete test for the GPWC can be done in the LRU itself. Level 1 Tests are performed in MAT for the flight deck indications though.

FMCF (Flight Management Computing Function)

• FMCF means Flight Management Computing Function located in the AIMS under CPM/STD.
• The FMCF selector switch is located in P3 in the flight deck.
• When the FMCF switch is in the auto position, the FMCFs are chosen at random to provide the command to the LNAV and VNAV.
• When the FMCF switch is on the left side and the FMCF L is inoperative, an on side CDU will give the command to display the flight plan in the ND.
• The main interface of pilots for the FMCF is the CDU.
• A lit MSG light in the CDU indicates a message in the scratchpad.
• A lit DSPY light in the CDU indicates disagreement of the actual phase to the display.
• A lit OFST light in the CDU indicates the track route is in parallel.
• The lateral flight plan uses a navigation data base, while the vertical flight plan uses a performance data base/airline policy.
• Airline policy can be accessed in the maintenance index.
• When both FMCFs are inoperative, the CDU will only provide LNAV.
• In the FMA, white signifies the ARM mode, and green the ACTIVE mode.
• LNAV becomes active at 50 feet, and VNAV at 400 feet.

AFDS (Automatic Flight Director System)

• The human machine interface for the AFDS and FMCF is the MCP for the AFDS and CDU for the FMCF.
• The autopilot system is available in all flight phases except takeoff.
• The B777 has 6 BDAs.
• In flight, 2 BDAs are engaged.
• L and R AFDCs are connected to BDA.
• On first autopilot engagement, 3 AFDCs are engaged, with the Right AFDC as the master.
• The autopilot can be disengaged outboard of the control wheel, triggering an aural sound, MWL, and EICAS message.
• Before re-engaging the autopilot, press the disengage switch to reset, and the Left AFDC becomes the new master.
• LNAV and VNAV can be armed on the ground, indicated by white color in the FMA.
• LNAV becomes active at 50ft, and VNAV at 400ft.
• Flight modes indication is visible on the FMA in the PFD.
• AFDCs are located in the E1, E2, and E4 racks.
• 3 inputs and 2 outputs of the ARINC 429 bus are connected to the MCP from the AFDC.
• Discrete signals in the AFDC come from the TO/GA switch, A/P Disconnect P/B, and A/P Disengage Bar.
• Cooling for the MCP comes from equipment cooling under the MCP.
• When the FD p/b is set to the ON position, the pitch and roll modes in FMA will show TO/GA, TO/GA.
• When the pitch mode is set to V/S, the auto thrust mode in the FMA will show SPD mode.
• When the selected V/S is reached, the auto thrust mode in the FMA will show SPD mode, and the pitch mode will show ALT mode.
• When the FLCH is set in the pitch mode, the auto thrust mode in the FMA will show THR.
• When the FLCH is selected but the pilot overrides the auto thrust system, the auto thrust mode in the FMA will show HOLD mode.
• Around 1500ft, 6 BDAs will engage.
• When the APP p/b in the MCP is pressed, the pitch and roll modes in the FMA will show LOC for the roll mode and G/S for the pitch mode.
• The FLARE and ROLLOUT modes will be armed in the FMA around 1500ft.
• There is no display info in the PFD for runway alignment.
• Runway alignment activates at 500ft, 500ft and 200ft, 200ft.
• BAP is available whether the autopilot is disengaged or engaged.
• When the autopilot is disengaged, the BDA for the control wheel will engage for BAP.
• There are 2 ASMs located below of P10 panel.
• The auto-throttle arm switches are located in the MCP.
• TMCF is part of AIMS inside of CPM/STD.
• When the FMCF switch is selected to the Left, the Left TMCF is active and can control 2 ASMs.
• Trim equalization command is available in manual and auto throttle, provided that both A/T switches are in the arm position.
• Auto throttle modes are indicated in the FMA in the PFD.
• Thrust limit modes are indicated in EICAS.
• Thrust limit modes are set in the CDU in the thrust limit page.
• The derated temperature can be used only for take-off thrust.

EFB (Electronic Flight Bag)

• The main purpose of the EFB is for paperless aircraft operation.
• The computer for the EFB is 2 EA EUs located in the E1 and E4 rack.
• The 28V DC supply of EFB DU comes from EUs.
• The PMAT can be connected to the P18 panel for external data loading for the EFB.
• To make sure that the same software is loaded to both EUs R and L, use CONFIG COMPARE under EFB MAINTENANCE.
• All loadable software parts can be seen in the EFB under SYSTEM CONFIG.
• Hardware part numbers and non-loadable software can be seen under INTERNAL CONFIG.
• The loading is performed under the LOAD mode in the FMC.
• Touch screen function is disabled when the LOAD mode is accessed in the EFB.
• The MMR system tells the aircraft position in the EFB.
• The components for the ONS are NFS and NED-DG.
• The EU is connected to the NFS.