flight safety embraer emb-120 brasilia pilot training manual

FlightSafety International, Inc.Marine Air Terminal, LaGuardia Airport

Flushing, New York 11371(718) 565-4100

www.flightsafety.com

FlightSafetyinternational

EMB-120 BrasiliaPILOT TRAINING MANUAL

VOLUME 2AIRCRAFT SYSTEMS

Copyright 1995 by FlightSafety International, Inc.All rights reserved.

Printed in the United States of America.

Courses for the EMB-120 Brasilia are taught at the following FlightSafety Learning Centers:

Long Beach Learning CenterLong Beach Municipal Airport4330 Donald Douglas DriveLong Beach, California 90808Phone: (562) 938-0100Toll-Free: (800) 487-7670Fax: (562) 938-0110

Atlanta Learning Center1010 Toffie TerraceAtlanta, Georgia 30354Phone: (678) 365-2700Fax: (678) 365-2699

Paris Learning CenterBP 25, Zone d Aviation d AffairesBldg. 404 Aeroport duBourget93352 Le Bourget, CEDEX FrancePhone: (+33) (1) 49-92-1919Fax: (33) (1) 49-92-1892

FOR TRAINING PURPOSES ONLY


NOTICEThe material contained in this training manual is based on information obtained from theaircraft manufacturers Pilot Manuals and Maintenance Manuals. It is to be used forfamiliarization and training purposes only.

At the time of printing it contained then-current information. In the event of conflictbetween data provided herein and that in publications issued by the manufacturer or theFAA, that of the manufacturer or the FAA shall take precedence.

We at FlightSafety want you to have the best training possible. We welcome anysuggestions you might have for improving this manual or any other aspect of ourtraining program.

CONTENTSChapter 1 AIRCRAFT GENERAL

Chapter 2 ELECTRICAL POWER SYSTEMS

Chapter 3 LIGHTING

Chapter 4 MASTER WARNING SYSTEM

Chapter 5 FUEL SYSTEM

Chapter 6 AUXILIARY POWER UNIT

Chapter 7 POWERPLANT

Chapter 8 FIRE PROTECTION

Chapter 9 PNEUMATICS

Chapter 10 ICE AND RAIN PROTECTION

Chapter 11 AIR CONDITIONING

Chapter 12 PRESSURIZATION

Chapter 13 HYDRAULIC POWER SYSTEMS

Chapter 14 LANDING GEAR AND BRAKES

Chapter 15 FLIGHT CONTROLS

Chapter 16 AVIONICS

Chapter 17 OXYGEN SYSTEMS

WALKAROUND

ANNUNCIATOR PANEL

INSTRUMENT PANEL POSTER

Revision 4 1-i

CHAPTER 1AIRCRAFT GENERAL

CONTENTSPage

INTRODUCTION ................................................................................................................... 1-1

GENERAL............................................................................................................................... 1-2

STRUCTURES........................................................................................................................ 1-2

General ............................................................................................................................. 1-2

Cockpit ............................................................................................................................. 1-5

Cabin ................................................................................................................................ 1-9

Doors.............................................................................................................................. 1-13

EMERGENCY EQUIPMENT .............................................................................................. 1-17General........................................................................................................................... 1-17

Emergency Locator Transmitter .................................................................................... 1-17

Emergency Exits ............................................................................................................ 1-19

Emergency Lighting....................................................................................................... 1-19

SYSTEMS ............................................................................................................................. 1-19

Electrical Systems.......................................................................................................... 1-19

Fuel System.................................................................................................................... 1-20

Auxiliary Power Unit ..................................................................................................... 1-20

Powerplant ..................................................................................................................... 1-20

Fire Protection................................................................................................................ 1-20

Ice and Rain Protection.................................................................................................. 1-20

Air Conditioning and Pressurization.............................................................................. 1-21

Hydraulic System........................................................................................................... 1-21


EMB-120 PILOT TRAINING MANUAL

FlightSafety international

Landing Gear and Brakes .............................................................................................. 1-21

Flight Controls ............................................................................................................... 1-21

Avionics ......................................................................................................................... 1-21

Oxygen........................................................................................................................... 1-22

PUBLICATIONS................................................................................................................... 1-22

QUESTIONS......................................................................................................................... 1-24



Revision 41-ii FOR TRAINING PURPOSES ONLY

Revision 4 1-iii

ILLUSTRATIONSFigure Title Page1-1 EMB 120 RT Brasilia ............................................................................................... 1-2

1-2 Exterior Three-View Drawing .................................................................................. 1-3

1-3 Turning Distance ...................................................................................................... 1-4

1-4 Danger Zones ........................................................................................................... 1-4

1-5 Cockpit Layout ......................................................................................................... 1-5

1-6 Overhead Panel......................................................................................................... 1-6

1-7 Windshield and Direct Vision Windows .................................................................. 1-7

1-8 Normal and Emergency Window Operation ............................................................ 1-7

1-9 Pilots Seats .............................................................................................................. 1-8

1-10 Observers Seat......................................................................................................... 1-8

1-11 Pedal Adjust Mechanism.......................................................................................... 1-81-12 Pilots Seat Adjustment ............................................................................................ 1-91-13 Passenger Configuration/Interior Layout (Typical) ............................................... 1-101-14 Attendants Station (Typical) ................................................................................. 1-111-15 Attendants Panel ................................................................................................... 1-12

1-16 Toilet....................................................................................................................... 1-12

1-17 Galley ..................................................................................................................... 1-12

1-18 Forward Door Controls .......................................................................................... 1-13

1-19 Door Warning Lights.............................................................................................. 1-13

1-21 Forward Entry Door Operation .............................................................................. 1-14

1-20 Forward Door Emergency Valve ............................................................................ 1-14

1-22 Cargo/Service Door Location ................................................................................ 1-15

1-23 Cargo Door Operation............................................................................................ 1-16




1-24 Doors Warning Lights (Overhead Panel) ............................................................... 1-161-25 Standard Emergency Equipment Location............................................................. 1-17

1-26 Life Vest Location and Operation .......................................................................... 1-18

1-27 Hand Hold Rope Location and Use ....................................................................... 1-18

1-28 Emergency Exit Operation ..................................................................................... 1-19



Revision 41-iv FOR TRAINING PURPOSES ONLY

INTRODUCTIONThis training manual provides a description of the major airframe and engine systemsinstalled in the EMB-120 Brasilia. The information contained herein is intended onlyas an instructional aid. This material does not supersede, nor is it meant to substitutefor, any of the manufacturers maintenance or operating manuals. The material presentedhas been prepared from current design data.

Chapter 1 covers the structural makeup of the airplane and gives an overview of the systems.

An annunciator section in this manual displays all annunciator and other light indica-tions and should be folded out for reference while reading this manual.

Review questions are contained at the end of most chapters. These questions are includedas a self-study aid, and the answers can be found in the appendix section.



CHAPTER 1AIRCRAFT GENERAL

1-1FOR TRAINING PURPOSES ONLY

GENERALThe EMB-120 Brasilia is certified in accor-dance w i th FAR Pa r t 25 a i rwor th ine s sstandards. It is designed for passenger andcargo transportation on typical commercialair carriers. There are three types: RT, ER,and FC.

The minimum crew requirements for operationsin the EMB-120 Brasilia are one pilot and onecopilot. The pilot-in-command must have aBrasilia type rating and meet the requirementsof FAR 61.58 for two-pilot operation. The copi-lot shall possess a multiengine rating and meetthe requirements of FAR 61.55.

STRUCTURESGENERALThe EMB-120 Brasilia (Figure 1-1) is an all-metal construction, pressurized, low-wingT-tail, monoplane. Two Pratt and WhitneyPW118 engines are mounted on the wing, sup-ported by a semimonocoque/tubular nacellestructure. The landing gear is the retractable,twin-wheel type.

Figure 1-2 shows a three-view drawing of theEMB-120 Brasil ia with the principal di-mensions. Figure 1-3 shows turning distance,and Figure 1-4 is a diagram of danger zones.



Revision 41-2 FOR TRAINING PURPOSES ONLY

Figure 1-1. EMB 120 RT Brasilia




61.45 FT(18.73 M)

(20.00M)(6.98M) 65.62 FT

22.90 FT

(6.35

M)

20.8

4 FT

)

64.90 FT19.78 M

21.59 FT6.58 M

WINGTOTAL AREA...... 424.46 FT 2 (39.43 M 2)ROOT CHORD ............ 9.22 FT (2.81 M)MEAN AERODYNAMICCHORD ....................... 6.56 FT(2.00 M)ASPECT RATIO............................. 9.92

HORIZONTAL TAILTOTAL AREA..... 107.65 FT 2(10.00 M )2ROOT CHORD.............. 6.00 FT(1.83 M)TIP CHORD.................. 3.64 FT (1.11 M)ASPECT RATIO............................ 4.63

VERTICAL TAIL

TOTAL AREA........... 74.28 FT2 (6.90 M )ROOT CHORD............10.43 FT(3.18 M)TAPER RATIO............................... 0.65DORSAL FINAREA....................... 15.39 FT 2

(1.43 M ) 2FUSELAGEOUTSIDEDIAMETER................... 7.48 FT (2.28 M)

22.7

7 FT

6.94

M(

2

30.54 FT(9.31 M)

WING REARSPAR

MAC6.56 FT(2.00 M)

26.21 FT(7.99 M)

REFERENCEORIGIN LINE

Figure 1-2. Exterior Three-View Drawing




61.85 FT(18.35 M)

50

51.71

FT

(4.08 M

)13

.39 FT

(15.76 M

)

47.07 FT(14.35 M)

35.76 FT

(10.90 M)29.89 FT(9.11 M)

APU EXHAUST27 FT RADIUS

AREA TO BECLEARED PRIORTO ENGINESTART

10 FT RADIUS

FULL THROTTLEVELOCITY FALLSBELOW 15 MPH

60 FT100 FT

Figure 1-3. Turning Distance

Figure 1-4. Danger Zones

COCKPITGeneralThe general layout of the cockpit is shown inFigure 1-5. The overhead panel is shown inmore detail in Figure 1-6.

Specific customer requirements may causesome instruments and equipment to vary fromstandard configuration.



Revision 4 1-5FOR TRAINING PURPOSES ONLY

OVERHEAD PANEL

FORWARD PANEL

PILOT'S CONSOLE CENTER CONSOLE

Figure 1-5. Cockpit Layout




Figu

re 1

-6.

Ove

rhea

d Pa

nel

Windshield and WindowsThe EMB 120 has two windshields and two di-rect vision windows (Figure 1-7). Only thewindshields are heated.

The direct vision windows may be partiallyopened dur ing normal opera t ion on theground. They may be totally removed in caseof loss of visibility through windshield or forc o c k p i t eva c u a t i o n . A W I N D OW N OT

CLOSED inscription, on the window frontframe, will be visible when the window is notclosed properly. Window operation is shownin Figure 1-8.

Crew SeatsThe pilots seats (Figure 1-9) are fixed to slidetracks which permit fore, aft, and lateral seatmovement. They are also equipped with a




Figure 1-7. Windshield and Direct Vision Windows

21

43

PRESSING LOCK BUTTON, PULL HANDLEIN AND BACKWARD

WINDOW PARTIALLY OPEN

TO REMOVE WINDOW FROM ITS TRACKPULL IT UP AND INWARD

PULL DOWN EMERGENCY HANDLE ANDTURN IT

Figure 1-8. Normal and Emergency Window Operation

height adjustment mechanism to lower or raisethe seat. The seats include quick-disconnectcombination lap belts and shoulder harnesswith inertial reels. Lateral seat movement ispossible only when the seat is in the full AFTposition.

Observers SeatA foldable jump seat (Figure 1-10), installed

in the floor at the cockpit entrance, may be usedfor an observer or a third crew member. Theobservers seat is provided with safety beltand inertia reel.

Pedal AdjustmentA mechanism under each pilots front panel(Figure 1-11), allows the pilots to adjust theirpedals for optimum position.




INERTIAL SHOULDERHARNESS

BUCKLE

VERTICAL ADJUSTMENTCONTROL HANDLE

INERTIAL SHOULDERHARNESS LOCKING HANDLE

TRACKSHORIZONTALADJUSTMENTCONTROL HANDLE

ARMREST

PILOT'SPEDALS

COPILOT'SPEDALS

PEDAL ADJUSTMECHANISM

Figure 1-9. Pilot Seats

Figure 1-10. Observers Seat Figure 1-11. Pedal Adjust Mechanism

Seat AdjustmentEach seat may be adjusted to position the pilotfor optimum control column operation usingthe alignment balls as shown in Figure 1-12.

This is accomplished by first moving the seatup or down until the pilots line of sight reachesthe same horizontal plane as the alignmentballs. Then, move the seat fore and aft so thatthe opposite white ball becomes aligned withthe black ball.

CABINFigure 1-13 shows typical passenger config-uration and internal layout.




LINE O

F SIG

HT

FRONT VIEW

TOPVIEW

WHITE(2)

BLACK

Figure 1-12. Pilot Seat Adjustment




Figure 1-13. Passenger Configuration/Interior Layout (Typical)

COPILOTSEAT

OBSERVERSEAT

TOILETPARTITION

ATTENDANT'SCABINET

TOILET CLOSET

SIDEPANEL

PASSENGERSEATS

REARPARTITION

CARGOCOMPARTMENTCLOSET

GALLEY

ATTENDANTSEAT

PILOTSEAT

COCKPIT

FRONTPARTITION

Attendants StationThe attendants station, shown in Figure 1-14,is located next to the forward entry door. It isprovided with interphone, folding seat, fire ex-tinguisher, two life vests, and a flashlight.

The attendants panel (Figure 1-15) has con-trols for the emergency lights, cabin lights,cabin temperature, and forward entry door.

ToiletThe toilet, as seen in Figure 1-16, is locatedopposite the forward entry door. On some ear-lier aircraft the toilet may be located in the rearof the aircraft. The galley (Figure 1-17) is lo-cated just aft of the forward entry door.




FIREEXTINGUISHER

FLASHLIGHT

ATTENDANT'SSEAT

(FOLDED IN)

ATTENDANT'SPANEL

ATTENDANT'SINTERPHONE

ATTENDANT'SCABINET

RH CLOSET

ATTENDANT'SPORTABLEOXYGEN CYLINDER

ATTENDANT'SSEAT IN POSITION

FOR USE

EXIT

EXIT

TOILET

TWO LIFEVESTS

Figure 1-14. Attendants Station (Typical)




PUSHEXIT

CABIN TEMPADJUST KNOB

EMERGENCYLIGHTING SWITCH

COURTESY LIGHT SWITCH

PAX CABINLIGHT SWITCH

FWD DOORCONTROL

INTERCOMPHONE

SPARETOILET-ROLL

STOWAGE

TOWEL AND DRY/MOISTENED TISSUE

HOLDER

"RETURN TO YOURSEAT" WARNING

SIGN

HANDLE

TOILET-ROLLHOLDER

WASTEDISPOSAL

TOILET ASSEMBLYSHROUD

TOILET SEAT

PUSH-PULLBUTTON FORFLUSHINGTOILET BOWLLIQUIDDISINFECTANT

COVER

ASHTRAYS

Figure 1-15. Attendants Panel

Figure 1-16. Toilet Figure 1-17. Galley

DOORSForward Entry DoorThe forward entry door, located just aft of thecockpit on the left side, incorporates foldingair stairs and is hinged at its lower edge.

In normal operation, the door is closed (raised)by two hydraulic door actuators, and opened(lowered) manually with hydraulic dampen-ing. With no hydraulic pumps operating, anaccumulator provides sufficient pressure forfour complete operations of the door. The doormay also be raised manually from outside bya ground attendant.

The door may be operated from either insideor outside the aircraft. The interior control islocated on the flight attendants panel just in-side the door, and the exterior control is on thefuselage at the lower left side of the door(Figure 1-18). Each control panel incorpo-rates a pushbutton which energizes a solenoidvalve, allowing hydraulic power to raise thedoor, and blue light that illuminates while thedoor is moving up. The interior control panelalso incorporates a circuit breaker.

With the door in the raised position it is thenclosed and locked by operation of either theinner or outer door handles.

When the forward door is not closed and lockedthe FORWARD light on the DOORS panel,shown in Figures 1-19 and 1-24, illuminates.

If the forward door actuator remains pressur-i z ed a f t e r c l o s ing , b lock ing t he doo rhydraulically, the FORWARD ACTUATORlight on the DOORS panel illuminates (Figures1-19 and 1-24). In this event, an emergencyvalve (Figure 1-20) is provided in the cockpitto allow the door to be lowered

Normal door operation from outside the air-craft is shown in Figure 1-21.




Figure 1-19. Door Warning Lights

PRESSCLOSEDOOR

FWD DOOR

CONTROL IN TRANSIT

PRESSCLOSEDOOR

CONTROL IN TRANSIT

EXTERIOR FWD DOORCONTROL PANEL

FWD DOOR

INTERIOR FWD DOORCONTROL PANEL

2

DOORSWARNING

CAUTIONALARM

CANCEL

FORWARDACTUATOR

FOWARD

CARGO

SERVICE

DOORS

Figure 1-18. Forward Door Controls




FORWARD DOOREMERGENCY VALVE

Figure 1-20. Forward Door Emergency Valve

TO OPEN PASSENGER/CREWENTRY DOORFROM THE OUTSIDE

PULLACTUATINGHANDLEOUTWARD

PULL DOOR

WAIT UNTIL DOOR ISFULLY LOWERED

OPENACCESSPANEL

DEPRESS DOORACTUATING BUTTON WAIT UNTIL DOOR

LIFTS UP TO ITS STOP

PUSH ANDLOCK DOOR

TO CLOSE PASSENGER/CREWENTRY DOORFROM THE OUTSIDE

Figure 1-21. Forward Entry Door Operation

Cargo/Service DoorsLocation of the cargo and service doors isshown in Figure 1-22.

Cargo DoorOperation of the cargo door is shown inFigure 1-23. The initial opening (displace-ment of the door inward) and final closing(displacement of the door outward) are con-trolled by the external handle in the lowerhalf of the door. This handle is also re-sponsible for door locking.

When the cargo door is not closed and lockedthe CARGO l igh t on the DOORS pane l(Figures 1-19 and 1-24) illuminates.

Service DoorsThe service doors are the external doors whichprovide maintenance access to airplane sys-tems and equipment.

The controls rigging door is located on thefuselage beneath the cockpit providing accessto the fuselage pressurized compartment. Theelectronic compartment door is located insidethe nose landing gear compartment. The fuelcompartment doors are located under the wingoutboard of the right engine nacelle.

If any door is not closed and locked theSERVICE light on the DOORS panel (Figures 1-19 and 1-24) illuminates.




CARGODOOR

FORWARDDOOR

ELECTRONICCOMPARTMENT

DOOR

CONTROLRIGGING

DOOR

REFUELINGCOMPARTMENT

DOORS

Figure 1-22. Cargo/Service Door Location




TO OPEN:

PUSH THE DOOR

2 3

PULL THE ROPE

4TURN THE HANDLE

AND PUSH IN TO LOCK

5

PULL HANDLE OUTAND TURN

1

TO CLOSE:

DOORS

FORWARD DOOR LIGHT (RED)

ILLUMINATED - WHEN THE FORWARDDOOR IS NOT CLOSED AND LATCHED.

SERVICE DOOR LIGHT (RED)

ILLUMINATED - WHEN THE CONTROLRIGGING DOOR OR ELECTRONICCOMPARTMENT DOOR IS NOT CLOSEDAND LATCHED.

NOTE:FOR AIRPLANES POST-MOD. SB 120-031-0008 ORSN 120.046, 120.050, AND SUBSEQUENT, THE SERVICE LIGHT IS ILLUMINATED WHENEVER ANY REFUELING/DEFUELING SYSTEM DOOR IS OPEN.

FORWARD ACTUATOR LIGHT (RED)

ILLUMINATED - WHEN THE FORWARDDOOR ACTUATORS HYDRAULIC LINE

REMAINS PRESSURIZED AFTER DOORCLOSING. FOWARD ENTRY DOOR IS

HYDRAULICALLY BLOCKED.

CARGO DOOR LIGHT (RED)

ILLUMINATED - WHEN THE CARGO DOOR IS NOT CLOSED AND LATCHED

FORWARDACTUATOR

FORWARD

CARGO

SERVICE

Figure 1-23. Cargo Door Operation

Figure 1-24. Doors Warning Lights (Overhead Panel)

EMERGENCY EQUIPMENTGENERALLocation of fire extinguishers, portable oxy-gen cylinders, oxygen masks, smoke goggles,escape ropes, and first aid kit is shown in Figure1-25. Emergency flashlights, though not shown,are also provided in the cockpit and cabin.

Passenger seat cushions can serve as a floata-tion device and are easily removable. Lifejackets for the attendant and observer are stowedin the attendants panel, and for the pilotsunder their seats (Figure 1-26). Escape ropelocation and use is shown in Figure 1-27.

EMERGENCY LOCATORTRANSMITTERAn Emergency Locator Transmitter (ELT) islocated in the dorsal fin (Figure 1-25). A re-mote switch on the copilots panel selectsei ther automat ic (ARM) or manual (ONRESET) activation. With the remote switch inthe ARM position, the ELT automaticallytransmits on 121.5 and 243.0 MHz when theairplane is subjected to a longitudinal decel-eration of 5 to 7 G.




CREW PORTABLEOXYGEN CYLINDER(BEHIND COPILOT'S

SEAT)COCKPITESCAPE

ROPE

EMERGENCY EXITSELT

OXYGEN MASK(ON LATERALCONSOLES)

CRASHAXE

FIRE EXTINGUISHER(BEHIND PILOT'S SEAT)

FIRE EXTINGUISHER(BEHIND ATTENDANT'S SEAT)

BAG CONTAININGFULL FACE MASK

AND SMOKE GOGGLES

PORTABLEOXYGEN CYLINDER

(RIGHT CLOSET)

FIRST AID KIT(GALLEY)

PAX EMERGENCY ROPE

Figure 1-25. Standard Emergency Equipment Location




4

JERK TO INFLATE. IF LIFEJACKET FAILS TO INFLATE,USE ORAL TUBE.

ORALTUBE

2

DON JACKET AND PUTSTRAPS AROUND BACK

3

BRING TO FRONT, MAKING SURE INFLA-TION TAB IS NOT UNDER WAIST STRAP.PROCEED TO SNAP ONTO "O-RING" ANDPULL SHORTENING TAB TO ADJUST.

1PILOT'S

SEAT

ATTENDANT'SSEAT

HAND HOLDROPES

REMOVE THE CARPETSTRAP (AIRPLANES

PRE-MOD SB 120-025-0081)

PASS ROPE AROUND SEATLEG (AIRPLANES POST-

MOD SB 120-025-0081 ORSN 120.035 AND ON)

OR

OR

SNAP HOOKONTO RING

1 2

3 4

Figure 1-26. Life Vest Location and Operation

Figure 1-27. Hand Hold Rope Location and Use

EMERGENCY EXITSIn addition to each pilots direct vision window,there are three emergency exits in the cabin ofthe aircraft. Two are overwing exits on each sideof the fuselage and one is a floor level exit onthe right rear side. All are plug-type exits thatopen to the inside of the cabin from either in-side or outside the fuselage. Emergency exitoperation is shown in Figure 1-28.

EMERGENCY LIGHTINGEmergency lighting is provided internallyfor each emergency exit door, the mainentry door, and the aisle. External lightingilluminates the wing and ground in thevicinity of each exit.

The emergency lights and their operationare covered in Chapter Three, Lighting.

SYSTEMSELECTRICAL SYSTEMSTwo 400-amp, 28-volt DC starter-generators,one on each engine, are the primary source ofelectrical power. Two 150-amp, 28-volt DCgenerators, one each in the propeller reductiongearbox, supply power to essential circuits incase of a complete failure of the primary 28VDC sources.The airplane AC power is provided by twostatic inverters, one being a standby.A 24-volt nickel-cadmium battery is designedto assist each starter-generator during theengine starting cycle, and supply essentialloads in the event of complete generator/en-gine failure.




1 2

3VALID FOR ALL EMERGENCY EXITS

REMOVE

Figure 1-28. Emergency Exit Operation

An emergency battery is available as a backupfor selected loads and to provide emergencypower for both the standby horizon and gen-erator control units (GCUs).A starter-generator installed on the APU, iden-tical to the main generators, is used to start theAPU. It may be used to provide electricalpower to all buses on the ground, and forstandby power in flight.

FUEL SYSTEMThe fuel system is made up of two tanks, onein each wing. Each wing tank is made up oftwo independent cells separated by the wheel-well. These inboard and outboard cells areinterconnected by tubes for gravity fuel trans-fer. Fuel is supplied to the engine by pumpsinstalled in a collector tank located in the low-est region of each inboard fuel cell. Each wingtank has a usable capacity of 437 US Gal.

Each engine is supplied independently fromits wing tank. A crossfeed line allows eitherwing tank to supply both engines simultane-ously. Gages for monitoring fuel flow and fuelquantity are located on the fuel managementpanel in the cockpit.

The aircraft may be gravity fueled using over-wing fillercaps, and manually defueled. Apressurized system is provided for faster fu-eling/defueling.

AUXILIARY POWER UNITThe APU, located in the tail cone, is a gas tur-bine engine used to supply pressurized air andelectrical power to the airplane.

POWERPLANTTwo Pratt and Whitney PW118 or PW118Aturboprop engines, both flat rated at 1800SHP, are mounted on the wings. The engine isa three-shaft, two-spool gas generator with afree power turbine.

Engine airflow is straight-through with airentering an intake below the propeller spinner,then through an S-duct to the engine. This S-duct provides inertial separation and protectionin the event of foreign object ingestion.

PropellerEach engine is equipped with a HamiltonSundstrand model 14 RF-9, four-blade, con-s t an t speed , r eve r s ib le , fu l l f ea the r ingpropeller. Automatic feathering and propellersynchronization systems are installed.

FIRE PROTECTIONFire detectors installed in the engine acces-sories section, wheelwell, pipe zones and APUcompartment provide fire or overheat warning.

The engine fire control panel, installed on thecenter glareshield panel, is provided with bot-tle discharge ability and INOP lights, shutoffvalve position indicators, fire warning lights,extinguishing handles, and a test button. TheAPU fire control panel on the overhead APUCONTROL panel, provides the means for APUfire detection and extinguishing.

A smoke detection system is installed for usewhen the a i rplane is conver ted to cargoconfiguration.

ICE AND RAIN PROTECTIONAn electrical anti-icing system protects the leftand right windshields, pitot/static tubes, staticports, angle of attack, and side slip sensors.

Electrical deicing system protects the pro-peller blades to permit unrestricted operationinto known icing conditions. The wings, sta-bilizers, vertical fin, and engine air inlets areprotected by inflatable deicers.

The rain removal system consists of two in-dependent two-speed wipers, one on eachwindshield.




AIR CONDITIONING ANDPRESSURIZATIONThe air-conditioning and pressurization sys-tem provides conditioned pressurized air to thecockpit and passenger cabin. The system is op-erated using bleed air from either the enginesor the APU.

The cockpit and passenger cabin are suppliedby separate air ducting with cross-connectingcapabilities. Temperature of the two zones isindependently controlled.

The cabin pressure control, designed to main-tain a 7 psi cabin/ambient pressure differential,maintains the cabin at sea level pressure up toan altitude of 16,800 ft. Control is accom-p l i shed by an e l ec t ropneuma t i c va lve(automatic mode) or by a pneumatic valve(manual mode).

HYDRAULIC SYSTEMHydraulic power is provided by two indepen-dent systems. Each system is powered by amain pump, driven by the left or right propellergearbox. DC powered electrical pumps providebackup pressure for each system. Two pres-surized hydraulic reservoirs are arranged sothat leakage in either of the systems will notaffect operation of the other. Each hydraulicreservoir is equipped with transmitters andswitches that display system status on the HY-DRAULIC POWER PANEL located on thecockpit overhead panel.

LANDING GEAR AND BRAKESThe landing gear is a conventional tricycle,dual-wheel, forward retracting type.

Three modes are provided for operation of thelanding gear:

Normal hydraulic retraction and extension Alternate electrical override extension Emergency free-fall extension with man-

ual release of the uplocks.

Nosewheel steering is controlled through asteering handle on the pilots left console.Limited nosewheel steering is available withthe rudder pedals.

A normal brake system is actuated by con-ventional means through the pilot or copilotrudder pedals and controlled by a dual anti-skidsystem.

An emergency brake sys tem is ac tuatedthrough a handle and control valve. Pressureto the brakes is proportional to handle dis-placement.

FLIGHT CONTROLSFlight controls are operated by conventionalcontrol wheels, columns, and rudder pedals forpilot and copilot. They are normally inter-connec t ed and j o in t l y ope ra t ed . I n anemergency, control wheels and columns maybe disconnected between the pilot and copi-lot, rendering the airplane controllable byeither. Pedals are independently adjustable, al-lowing comfortable operation.

The elevators and ailerons are mechanicallyactuated. The rudder is hydraulically actu-ated with a mechanical back-up.

The flaps, divided into three panels per wing,are hydraulically actuated.

Elevator and aileron trim is by mechanical ac-tuators to trim tabs. Rudder trim is hydraulic.

AVIONICSFlight instrumentsConventional air data instruments (airspeed,altimeter, and vertical speed indicator) areprovided with separate pitot/static sources forpilot and copilot.

An independent standby attitude indicator onthe center panel, and a standby compass inthe top of the windshield center post, provideback-up attitude and heading information.




NavigationThe navigation system includes the followingequipment:

Electronic flight instrument system(EFIS)

Two independent attitude and headingreference systems (AHRS)

Two radiomagnetic indicators (RMI) Two distance measuring equipment

(DME) systems Two VHF/NAV(VOR/ILS/MB) radios Two ATC transponders One automatic direction finder (ADF) One radio altimeter system

The EFIS displays consist of two electronic at-t i t ude d i r ec to r i nd i ca to r s (EADI) , twoelectronic horizontal situation indicators(EHSI), and a multifunction display (MFD).The EADI and EHSI are color cathode-raytube displays.

The AHRS provides attitude and heading sig-nals to the EFIS and autopilot/flight director;pitch and roll angle to the weather radar; andturn rate and normal acceleration data to theautopilot, if required.

Radar is displayed on the multifunction displayand each EHSI when in the ARC or map mode.

AutoflightThe autoflight system is a fully integratedthree-axis dual flight control system includ-ing manual electric trim. It is divided into twogeneral systems:

Flight director system Autopilot system

Available functions include heading, altitude andairspeed control, VOR/ILS approach coupling,glide-slope operation, and go-around mode.

CommunicationThe communication system includes:

Interphone for communication betweenpersonnel in the cockpit, and flight crewmembers and cabin/ramp personnel

Passenger address system for commu-nication between flight crew membersand passengers

VHF for air-to-air and air-to-groundcommunication.

The airplane is equipped with a cockpit voicerecorder.

OXYGENThe airplane is equipped with a conventionalgaseous oxygen system. One oxygen cylin-der supplies low-pressure oxygen to both thecrew and passenger systems. The crew systemconsists of three quick-donning masks. Thepassenger system consists of continuous flowmasks in dispensing units, installed in theaisle ceiling. The units open automatically,when cabin altitude exceeds 14,000 feet, ormanually by a switch installed on the controlstand in the cockpit.

Other related equipment includes portableoxygen cylinders, smoke goggles, and fullface masks.

PUBLICATIONSThe FAA-approved Airplane Flight Manual(AFM) is a required flight item. It contains thelimitations, operating procedures, performancedata pertinent to takeoffs and landings, andweight and balance data. It does not containenroute performance information. The AFMalways takes precedence over any other pub-lication.

The EMB 120 Operating Manual contains ex-panded descriptions of the airplane systemsand operating procedures. It contains enrouteflight planning information as well as sometakeoff and landing performance information.




The EMB120 check l i s t (QRH QuickReferrence Handbook) contains abbreviatedope ra t i ng p rocedu re s and abb rev i a t edperformance data. If any doubt exists or if theconditions are not covered by the checklist, theAFM must be consulted.

The EMB 120 Weight and Balance Manualcontains detailed infomation in the form oftables and diagrams. However, it is not requiredto be in the airplane as the basic empty weightand moment and means of determining thecenter-of-gravity location are all containedin the AFM.




1. The EMB 120 is certified under:A. FAR Part 25B. FAR Part 61C. FAR Part 91D. Brazilian CAA Paragraph 7

2. The EMB 120 has how many generators?A. 2B. 3C. 4D. 5

3. The EMB 120 forward entry door may be:A. Raised and lowered electricallyB. Raised and lowered manuallyC. Raised hydraulicallylowered man-

uallyD. Both B and C

4. The EMB 120 direct vision windows maybe removed by the crew.A. TrueB. False

5. If the main entry door is not securelyclosed and locked:A. An alarm will sound at the flight at-

tendants station.B. A door open light will illuminate in

the cockpit.C. A door solenoid will prevent engine

start.D. There is no indication of this situation.

6. How many cycles can the forward entrydoor be operated without recharging itsaccumulator?A. 1B. 2C. 3D. 4




QUESTIONS



FOR TRAINING PURPOSES ONLYRevision 4 2-i

CHAPTER 2ELECTRICAL POWER SYSTEMS

CONTENTSPage

INTRODUCTION ................................................................................................................... 2-1

GENERAL............................................................................................................................... 2-1

DC POWER............................................................................................................................. 2-2

Components ..................................................................................................................... 2-2

Distribution ...................................................................................................................... 2-6

Control and Monitoring ................................................................................................... 2-9

AC POWER........................................................................................................................... 2-12

Components ................................................................................................................... 2-12

Distribution .................................................................................................................... 2-12

Control and Monitoring ................................................................................................. 2-12

ELECTRICAL SYSTEM OPERATION............................................................................... 2-12

Normal Mode................................................................................................................. 2-15

Emergency Mode ........................................................................................................... 2-20

Overcurrent Protection................................................................................................... 2-22

PRE MOD SB 120-024-00051 ELECTRICAL SYSTEM DIFFERENCES ........................ 2-29

ELECTRICAL CONTROL PANEL SUMMARY ................................................................ 2-37

QUESTIONS......................................................................................................................... 2-39

Revision 4 2-iii

ILLUSTRATIONSFigure Title Page2-1 Electrical Component Location................................................................................ 2-2

2-2 Battery Location....................................................................................................... 2-2

2-3 Battery Temperature Gage........................................................................................ 2-3

2-4 Backup Battery Switch............................................................................................. 2-4

2-5 External Power Receptacle....................................................................................... 2-5

2-6 Power Select Switch ................................................................................................. 2-5

2-7 Central DC Power Distribution ................................................................................ 2-6

2-8 Auxiliary DC Power System .................................................................................... 2-7

2-9 Backup DC Power System ....................................................................................... 2-8

2-10 Radio Master System................................................................................................ 2-9

2-11 Electrical Control PanelDC System ................................................................... 2-11

2-12 AC Power System .................................................................................................. 2-13

2-13 Electrical Power System......................................................................................... 2-14

2-14 Electrical System ConfigurationBattery Only.................................................... 2-16

2-15 Electrical System ConfigurationExternal Power................................................ 2-17

2-16 Electrical System ConfigurationAPU Generator ............................................... 2-18

2-17 Electrical System ConfigurationSingle Engine.................................................. 2-19

2-18 Emergency ModeBoth Main Generatorsand One Auxiliary Generator Failure..................................................................... 2-21

2-19 Emergency ModeTotal Generator Failure .......................................................... 2-23

2-20 Overcurrent Case 1: Short Circuit, Central DC Bus............................................... 2-24

2-21 Overcurrent Case 2: Short Circuit, Relay Box DC Bus 1 ...................................... 2-26

2-22 Overcurrent Case 3: Short Circuit, Relay Box DC Bus 2 ...................................... 2-28




Revision 42-iv

2-23 Circuit-Breaker Panel............................................................................................. 2-35

2-24 Electrical Control Panel ......................................................................................... 2-36

TABLETable Title Page2-1 Electrical Bus Equipment Distribution................................................................... 2-30






2-1

INTRODUCTIONThis chapter provides a description of the EMB-120 Brasilia Mod SB 120-024-0008 electrical powersystem; (Pre Mod differences are covered in the final section.) Included is information on the DCand AC systems. The DC system consists of storage, generation, distribution, and system mon-itoring. The AC system consists of generation, distribution, and system monitoring. Provision ismade for a limited supply of power during emergency conditions in flight, and for connection ofan external power unit while on the ground.

GENERALThe primary electrical power for the EMB-120Brasilia is 28 VDC. Two main and two auxiliarygenerators are the primary power sources. Secondarysources that may be utilized are: an external powersource; the auxiliary power unit (APU) generator;or the aircrafts nickel-cadmium battery. An addi-tional battery supplies backup power to essential instru-ments and the standby horizon.

Distribution of DC power is primarily via twogroups of buses, normally connected by a tie bus (thecentral DC bus). Each group of buses may be iso-lated from the central DC bus and powered by itsrespective generator. In flight, three buses are nor-mally connected to the auxiliary generators. Theemergency buses, normally connected to the rightmain generator, may be switched automatically ormanually to other power sources in the event of maingenerator power loss.

#1 SE

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CHAPTER 2ELECTRICAL POWER SYSTEMS

Revision 2

2-2

AC electrical power is provided by either of two 250-VA, 400 Hz static inverters which convert 28 VDCpower into 115 and 26 VAC. In normal operation,inverter No.1 powers the four AC buses, withinverter No.2 as standby power.

DC POWERCOMPONENTSMany of the electrical system components are locat-ed in the nose of the aircraft (Figure 2-1). They areaccessible through either the electronic compartmentdoor inside the nose landing gear compartment, or indi-vidual panels on the outside of the aircraft.

BatteriesThere are two batteries installed on the EMB 120: A24-VDC, 36 ampere-hour, nickel-cadmium mainbattery, and a 24-VDC, 5 ampere-hour, sealed lead-acid, backup battery. Both are located in the nose of

the aircraft and accessible through a panel just forwardof the cockpit on the left side (Figure 2-2).In flight, forced airflow is provided to the batterycompartment to ensure suitable ventilation for themain battery.




APUFIREWALL

APU GEN

APU ELECTRONICCONTROL UNIT

PRESSUREFRAME

PRESSUREFRAME

LEGENDMAIN GENERATORSMAIN GENERATORAPU GENERATORAUXILIARY GENERATOREXTERNAL POWER

EXTERNALPOWER

BATTERY

FIREWALLGEN 1

FIREWALLGEN 2

AUX GEN 1

AUX GEN 2

AUX GEN 1 GCUGEN 1 GCU

AUXILIARYRELAY BOX

AUX GEN 2 GCUGEN 2 GCUAPU GEN GCU

DC 1 RELAY BOX

DC 2 RELAY BOX

BATTERYRELAY BOX

INVERTERS

BATTERY

EMERGENCYBATTERY

Figure 2-2. Battery Location

Figure 2-1. Electrical Component Location

Revision 4 2-3

Main BatteryThe main battery is connected in parallel with themain generators. It is designed to power each gen-erator during the engine starting cycle when exter-nal power is not available. It will also supplyessential loads for approximately 30 minutes in theevent of loss of all generators.

The battery is always connected to the hot battery bus.

Positioning the PWR SELECT switch to BATT ener-gizes the battery contactor closed, connecting thebattery to the central DC bus. The battery contac-tor is provided with a protective device that openswhen the current from the central DC bus to the bat-tery exceeds 500 amps.

On the ground with the battery as the only powersource, a safety circuit inhibits power to the recir-culation fans, gasper fan, and ground cooling fans.

Battery Temperature Monitoring System. Abattery temperature monitoring system is used to warnthe crew of a battery overheat condition.




BATTERYOVERHEATTEST BUTTON

Figure 2-3. Battery Temperature Gage



Revision 42-4

A gage on the cockpit overhead electrical panel(Figure 2-3), displays battery temperature in thefollowing ranges:

15 to 60C . . . . . . . . . . . . . . . . Green arc

60 to 70C . . . . . . . . . . . . . . . Yellow arc

70 to 85C . . . . . . . . . . . . . . . . . . Red arc

If the battery temperature exceeds 70C, the Bat-tery voice warning sounds, the BATT OVER-HEAT light on the multiple alarm panel illuminates,and the master WARNING lights flash.

The system incorporates two individual tempera-ture sensing elements in the battery case. One pro-vides a signal for the gage and the other a signal forthe warning system.

To test the sensing system, press and hold the bat-tery overheat test button on the battery temperaturegage. Heating elements heat the two sensors, caus-ing the temperature indication to rise. When the tem-perature reaches 70C, the alarm and warningsare triggered. Release the test button.

After the test button is released, the temperature willcontinue to rise briefly. It should then decrease andthe alarm and warnings stop. Holding the test but-ton beyond the warning activation point may cause

damage to the sensing elements.

During the test the two sensors are heated by sep-arate heating elements. This may cause a variationbetween the warning activation and the gage tem-perature. Minor differences are not a problem.


Figure 2-4. Backup Battery Switch




Backup Battery

The primary purpose of the backup battery is to pro-vide an uninterrupted source of power to the stand-by artificial horizon should the normal powersupply fail.

Its secondary purpose is to provide a stabilizedpower supply to sensitive electronic components dur-ing power transients such as engine starts.

The backup battery is controlled by a three-position(OFFARMTEST) switch on the center panel(Figure 2-4). The normal in-flight position for thisswitch is ARM.

Starter-GeneratorsWith one installed in each engine, two 28-VDC, 400-amp (600-amp during start) engine-driven starter-generators are the primary power source for theelectrical system. They may be connected inde-pendently or in parallel to the main distribution buses.

During engine start, the starter-generators act asmotors and are powered by the central DC busthrough the respective engine start contactor. At50% NH, (high-pressure compressor speed) whenthe starting cycle is completed, the generatorcontrol unit (GCU) automatically opens the enginestart contactor allowing the starter-generator to oper-ate as a generator.

The engine-driven starter-generators are connect-ed to the aircraft electrical system by the maingenerator contactors. The GCUs command the

Figure 2-5. External Power Receptacle

Figure 2-6. Power Select Switch

Revision 4

Revision 42-6

closure of these contactors when the main gener-ator switches, on the overhead electrical panel, arepositioned to ON.

Auxiliary GeneratorsTwo 28-VDC, 150-amp generators, each drivenby its respective propeller reduction gearbox, sup-ply power to the auxiliary power system.

The auxiliary generators are not connected to the

aircraft electrical system unless the propeller speed(NP) is greater than 70%.

APU Starter-GeneratorThe APU starter-generator is identical to the mainstarter-generators.

When the APU turbine reaches 95% rpm, theAPU generator is able to provide its nominalelectrical power output.




EMERGENCY DC BUS 2EMERGENCY DC BUS 1

RELAY BOXEMERGENCY DC BUS 2


RELAY BOX DC BUS 2

RIGHT ENGINESTARTER-GENERATOR

MAIN GENERATORCONTACTOR2ENGINE

STARTCONTACTOR 2

ENGINESTART

CONTACTOR 1 APUSTARTCONTACTOR

EMERGENCYBATTERYCONTACTOR

BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY

EXTERNALPOWER

EXT POWERCONTACTOR

CENTRAL DC BUSBUS TIE

CONTACTOR2

BUS TIECONTACTOR

1

APUGENERATORCONTACTOR

APUSTARTER-GENERATOR

LEFT ENGINESTARTER-GENERATOR

MAIN GENERATORCONTACTOR

1

EMERGENCYBUS

CONTACTOR

DC BUS 2

DC BUS 1

RELAY BOX DC BUS 1

EMERGENCYBUS

CONTACTOR 2

Figure 2-7. Central DC Power Distribution



2-7

The main purpose of the APU generator is to sub-stitute for the external power unit on the ground. Itmay also be used in parallel with the battery to powera starter-generator during engine start.

In flight, if required, the APU generator may be usedin parallel with the main generators.

External PowerAn external power unit may be connected to the air-craft DC system through a receptacle located justaft of the battery compartment panel (Figure 2-5).Placing the PWR SELECT switch on the overheadelectrical control panel (Figure 2-6) to the EXTPWR position closes the external power contac-tor, allowing the external source to power thecentral DC bus.

A protective circuit prevents the APU generator andthe external power source from simultaneouslysupplying the central DC bus; priority is external


AUXILIARY DC BUS

RELAY BOXDC BUS 3

DC BUS 3AUXILIARYTRANSFER

RELAY

EMERGENCYSWITCHING

RELAYAUX GENCONTACTOR1

AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2

BUS 3 RELAY

RELAY BOX DC EMERGENCY BUS 2RELAY BOX DC EMERGENCY BUS 1

Figure 2-8. Auxiliary DC Power System

Revision 4

Revision 42-8

power. A similar circuit also prevents the maingenerator and the external power source fromsimultaneously supplying the central DC bus; pri-ority in this case is the main generator.

An overvoltage relay protects the central DC bus ifexternal power exceeds 32 VDC. In this condition, theexternal power contactor will open, disconnecting theexternal power from the central DC bus.

The external power voltage may be monitored on

the left voltammeter by setting the voltammeter selec-tor to the CENTRAL BUS/APU GEN position.

DISTRIBUTIONCentral DC SystemDirect current is distributed throughout the air-craft as shown in Figure 2-7.

Each main generator is normally connected to the




VSUSTANDBYHORIZON BACKUP

BATTERYRELAY

BACKUP BATTERY

BACKUPBATT

SWITCH

OFFTEST

ARM

NORM

AUX GEN 1/2 GCUGEN 1/2 GCU

EMERGEMERGENCY

SWITCHING RELAY

EMERGENCYDC BUS 2

EMERGENCYDC BUS 1

STBY HORIZ EMERG BUS

BACKUP DC BUS 1 BACKUP EMERG DC BUS 1 BACKUP EMERG DC BUS 2 BACKUP DC BUS 2

DC BUS 1 EMERG DC BUS 1 EMERG DC BUS 2 DC BUS 2

AURAL WARNING AHRS 1 NH AND T6 ENG 1 INDICATIONS RCCBs FOR: L HYD AUX PUMP

L PROP HEATERRECIRC FAN 1L WSHLD DEICEGASPER FANTAXI LIGHTL GRND COOL FAN

AHRS 2 NH AND T6 ENG 2 INDICATIONS RCCBs FOR: R HYD AUX PUMP

R PROP HEATERRECIRC FAN 2R LDG LIGHTR WSHLD DEICER GRND COOL FAN

EEC 1 IGNITION LIGHT 1 RCCB FOR L AUX FEATHER PUMP

CLOCK/CHRONO EEC 2 IGNITION LIGHT 2 RCCBs FOR: R AUX FEATHER PUMP

L LDG LIGHT

Figure 2-9. Backup DC Power System




central DC bus, which functions as a tie bus. Thisallows either generator to supply the entire air-craft electrical load.

The battery is always connected directly to thehot battery bus. During normal operation, the powersource energizing the central DC bus powers the hotbattery bus and charges the battery.


RELAY BOXEMERGENCYDC BUS 1

RELAY BOXEMERGENCY

DC BUS 2

RELAYBOXDC BUS 1

RELAY BOXDC BUS 2

DC BUS 2

RADIO MASTERDC BUS 2A

RADIO MASTERDC BUS 2B

RADIO MASTERDC BUS 2C

ON

OFFNORMAL

RADIO MASTER

AHRS 2 DC

1 2AUXGCUs

ON

ON

OFF

OFF

EMERGENCYRADIO MASTER

NORMALRADIO MASTER

RADIO MASTEREMERG DC BUS 1




AHRS 1 DCRMI 2

1 2 AUXGCUs

Figure 2-10. Radio Master System



2-10

Auxiliary DC SystemWhen propeller speed (NP) reaches 70%, the aux-iliary generator control unit (GCU) connects the aux-iliary generator to the auxiliary DC bus (Figure 2-8).(The auxiliary generators are the only power sourcefor the auxiliary DC bus.)When powered, the auxiliary DC bus, energizes arelay that shifts the bus 3 contactor, switching bothrelay box DC bus 3 and DC bus 3 from relay boxDC bus 2 to the auxiliary DC bus.

When NP drops below 70%, the auxiliary GCU dis-connects the generator from the auxiliary DC bus. Ifthe auxiliary DC bus loses power (both auxiliarygenerators below 70%), both relay box DC bus 3 andDC bus 3 switch back to relay box DC bus 2.

The auxiliary GCUs also switch the primary nav-igation equipment (AHRS 1, AHRS 2, RMI 2,and radio master DC bus 1A and 2C) to the emer-gency buses.

FOR TRAINING PURPOSES ONLY Revision 4




Figure 2-11. Electrical Control PanelDC System

2-12 FOR TRAINING PURPOSES ONLY



Backup DC Power SystemThe backup power system (Figure 2-9) consists ofthe backup battery, the BACKUP BATT switchon the center panel, and the following buses:

Backup DC bus 1

Backup DC bus 2

Backup emergency DC bus 1

Backup emergency DC bus 2

Standby horizon emergency bus

Through one-way diodes, each backup bus is joint-ly connected to essential instruments normallypowered by one of the four main DC buses (DC bus1, DC bus 2, emergency DC bus 1, emergency DCbus 2).The backup battery system operates in the normalmode whenever the BACKUP BATT switch is in theARM position (and the electrical DC system isoperating in the normal mode). In this mode, all fivebuses are in a powered, standby status. The back-up battery is charged by emergency DC bus 2, andthe standby attitude indicator is powered by emer-gency DC bus 1.

If the voltage on any of the four main DC buses dropsbelow the voltage of their respective backup buses,power will be supplied to essential instrumentsthrough the backup buses.

The backup bus circuit breakers are all rated oneamp higher than the corresponding main DC buscircuit breakers. As a result, the main bus circuitbreakers on the overhead panel open before the back-up bus circuit breakers. This feature assists faultdetection by the pilot.

Revision 4




RADIO MASTERDC BUS 2C EMERGENCYDC BUS 1

DC BUS 2

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL 1

TRANSFERCONTROL 2

115-VACESSENTIAL BUS

26-VACESSENTIAL BUS

115-VACEMERGENCY BUS

26-VACEMERGENCY BUS

INVERTERNO. 2INVERTER

NO. 1

Figure 2-12. AC Power System

EM

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international

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evision 4

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL 1

TRANSFERCONTROL 2

115-VACESSENTIAL BUS

26-VACESSENTIAL BUS

115-VACEMERGENCY BUS

26-VACEMERGENCY BUS

VSUSTANDBYHORIZON


BACKUPBATTERYRELAY

BACKUP BATTERYBACKUP

BATTSWITCH

OFFTEST

ARM

NORM

50

35

80

200 225 200

15

200

80

35

EMERGEMERGENCY

SWITCHING RELAY

AUXILIARY DC BUS

RELAY BOXDC BUS 3


RELAY

EMERGENCYSWITCHING


AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2

BUS 3 RELAY




RELAY BOX DC BUS 2


MAIN GENERATORCONTACTOR2

ENGINESTARTCONTACTOR

ENGINESTART

CONTACTOR APUSTART

CONTACTOR


BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY




ON

OFFNORMAL

RADIO MASTER

AHRS 2 DC

1 2AUXGCUsEXTERNALPOWER

EXT POWERCONTACTOR


CONTACTOR2

BUS TIECONTACTOR

1





1

EMERGENCYBUS

CONTACTOR 1 EMERGENCYBUSCONTACTOR 2

ON

ON

OFF

OFF

EMERGENCYRADIO MASTER

NORMALRADIO MASTER

RADIO MASTEREMERG DC BUS 1




AHRS 1 DCRMI 2

1 2 AUXGCUs

LEFT MAIN DC GENERATOR

RIGHT MAIN DC GENERATOR

APU GENERATOR

AUXILIARY GENERATORS

EXTERNAL POWER

AC (INVERTER NO. 1)STANDBY AC (INVERTER NO. 2)MAIN BATTERY

BACKUP BATTERY


INVERTERNO. 2INVERTER

NO. 1

DC BUS 2

DC BUS 1

RELAY BOX DC BUS 1

LEGEND

Figure 2-13. Electrical Power System



Radio Master SystemDuring the engine starting cycle, bus voltage tran-sients may cause damage to communication and nav-igation instruments. To avoid this, the radio masterswitches allow the pilot to turn off the avionics dur-ing engine start.

There are two radio master switches, onelabeled EMERG and the other labeled NORMAL(Figure 2-10).The radio master system consists of the radio mas-ter switches, six normal radio master buses, and oneemergency radio master bus.

With both radio master switches in the ON position,the three corresponding relays are deenergized.This connects DC power to the radio master system.

When the switches are in the OFF position, the relaysare energized and power is removed from the radiomaster system.

CONTROL AND MONITORINGControl of the DC electrical system is accom-plished automatically through the five generator con-trol units (GCUs), and manually by switch positionon the overhead electrical control panel.

Monitoring of the electrical system is through thegages and indicator lights on the overhead electri-cal control panel.

GCUsThe main/APU starter-generators and the auxiliarygenerator are controlled by individual GCUs. Thesemultifunction units also provide electrical faultprotection.

Functions of the starter-generator GCUs are asfollows:

Initiates start cycle:

Closes start contactor

Energizes ignition circuit

Energizes return solenoid to empty draincollector (EPA) tank

Allows up to 600 amps for generator-aided cross start

Provides overspeed protection in eventof sheared shaft

Cancels start cycle at 50% RPM:

Opens start contactor

Deenergizes ignition circuit

Deenergizes EPA return solenoid

Enables the generator function

Regulates generator output between 26 and30 VDC (Normal 28.5 VDC)

Overvoltage protection (> 32 VDC) Overcurrent protection (> 400 amps) Reverse current protection

Generator field over excitation protection

Paralleling protection (maintains generatorloads within 10%)

2-15FOR TRAINING PURPOSES ONLYRevision 4

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115-VAC ESS

26-ESS AC

115-VAC EM

26-VAC EM

VSUSTBYHORIZ


BACKUPBATTERYRELAY


BATTSWITCH

OFFTEST

ARM

NORM

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL1

TRANSFERCONTROL2

50

35

80

200 225 200

15

200

80

35

EMERGEMERGENCY

SWITCHING RELAY

AUXILIARY DC BUS

RBDC BUS 3


RELAY

EMERGENCYSWITCHING


AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2

BUS 3 RELAY


RBEMERGENCY DC BUS 2


RB DC BUS 2




ENGINESTART

CONTACTOR APUSTART

CONTACTOR


BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY

RMDC BUS 2A

RMDC BUS 2B

RMDC BUS 2C

ON

OFFNORMAL

RM

AHRS 2 DC


EXT POWERCONTACTOR


CONTACTOR2

BUS TIECONTACTOR

1





1

EMERGENCYBUS

CONTACTOR 1

ON

ON

OFF

OFF

EMERGENCYRM

NORMALRM

RMEMERG DC BUS 1

RMDC BUS 1A

RMDC BUS 1B

RMDC BUS 1C

AHRS 1 DCRMI 2

1 2 AUXGCUs


DC BUS 2

DC BUS 1

RB DC BUS 1

INV 2INV 1

AC (INV 1)

STANDBY AC (INV 2)

MAIN BATTERY

BACKUP BATTERY

LEGEND

EMERGENCYBUS

CONTACTOR 2

Figure 2-14. Electrical System ConfigurationBattery Only

EM

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PILO

T T

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G M

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FlightSafety

international2-17

FOR TR

AININ

G PURPOSES ON

LYR

evision 4

115-VAC ESS

26-ESS AC

115-VAC EM

26-VAC EM

VSUSTBYHORIZ


BACKUPBATTERYRELAY


BATTSWITCH

OFFTEST

ARM

NORM

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL1

TRANSFERCONTROL2

50

35

80

200 225 200

15

200

80

35

EMERGEMERGENCY

SWITCHING RELAY

AUXILIARY DC BUS

RBDC BUS 3


RELAY

EMERGENCYSWITCHING


AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2

BUS 3 RELAY







ENGINESTART

CONTACTOR APUSTART

CONTACTOR


BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY

RMDC BUS 2A

RMDC BUS 2B

RMDC BUS 2C

ON

OFFNORMAL

RM

AHRS 2 DC


EXT POWERCONTACTOR

CENTRAL DC BUS

BUS TIECONTACTOR

2

BUS TIECONTACTOR

1





1

EMERGENCYBUS

CONTACTOR 1

ON

ON

OFF

OFF

EMERGENCYRM

NORMALRM

RMEMERG DC BUS 1

RMDC BUS 1A

RMDC BUS 1B

RMDC BUS 1C

AHRS 1 DCRMI 2

1 2 AUXGCUs


DC BUS 2

DC BUS 1

RB DC BUS 1

INV 2INV 1

AC (INV 1)

STANDBY AC (INV 2)

MAIN BATTERY

BACKUP BATTERY

EXT PWR

LEGEND

RB DC BUS 2

EMERGENCYBUS

CONTACTOR 2

Figure 2-15. Electrical System ConfigurationExternal Power

EM

B-1

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PILO

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international

2-18FOR

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RPOSES ON

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evision 4

115-VAC ESS

26-ESS AC

115-VAC EM

26-VAC EM

VSUSTBYHORIZ


BACKUPBATTERYRELAY


BATTSWITCH

OFFTEST

ARM

NORM

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL1

TRANSFERCONTROL2

50

35

80

200 225 200

15

200

80

35

EMERGEMERGENCY

SWITCHING RELAY

AUXILIARY DC BUS

RBDC BUS 3


RELAY

EMERGENCYSWITCHING


AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2

BUS 3 RELAY







ENGINESTART

CONTACTOR APUSTART

CONTACTOR


BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY

RMDC BUS 2A

RMDC BUS 2B

RMDC BUS 2C

ON

OFFNORMAL

RM

AHRS 2 DC


EXT POWERCONTACTOR


CONTACTOR2

BUS TIECONTACTOR

1





1

EMERGENCYBUS

CONTACTOR 1

ON

ON

OFF

OFF

EMERGENCYRM

NORMALRM

RMEMERG DC BUS 1

RMDC BUS 1A

RMDC BUS 1B

RMDC BUS 1C

AHRS 1 DCRMI 2

1 2 AUXGCUs


DC BUS 2

DC BUS 1

RB DC BUS 1

INV 2INV 1

AC (INV 1)

STANDBY AC (INV 2)

MAIN BATTERY

BACKUP BATTERY

APU GEN

LEGEND

RB DC BUS 2

EMERGENCYBUS

CONTACTOR 2

Figure 2-16. Electrical System ConfigurationAPU Generator

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115-VAC ESS

26-ESS AC

115-VAC EM

26-VAC EM

VSUSTBYHORIZ


BACKUPBATTERYRELAY


BATTSWITCH

OFFTEST

ARM

NORM

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL1

TRANSFERCONTROL2

50

35

80

200 225 200

15

200

80

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EMERGEMERGENCY

SWITCHING RELAY

AUXILIARY DC BUS

RBDC BUS 3


RELAY

EMERGENCYSWITCHING


AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2

BUS 3 RELAY







ENGINESTART

CONTACTOR APUSTART

CONTACTOR


BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY

RMDC BUS 2A

RMDC BUS 2B

RMDC BUS 2C

ON

OFFNORMAL

RM

AHRS 2 DC


EXT POWERCONTACTOR

CENTRAL DC BUS

BUS TIECONTACTOR

2

BUS TIECONTACTOR

1





1

EMERGENCYBUS

CONTACTOR 1

ON

ON

OFF

OFF

EMERGENCYRM

NORMALRM

RMEMERG DC BUS 1

RMDC BUS 1A

RMDC BUS 1B

RMDC BUS 1C

AHRS 1 DCRMI 2

1 2 AUXGCUs


DC BUS 2

DC BUS 1

RB DC BUS 1

INV 2INV 1

AC (INV 1)

STANDBY AC (INV 2)

MAIN BATTERY

BACKUP BATTERY

AUXILIARY GENERATOR

R MAIN DC GEN

LEGEND

RB DC BUS 2

EMERGENCYBUS

CONTACTOR 2

Figure 2-17. Electrical System ConfigurationSingle Engine

Revision 42-20

Functions of the auxiliary generator GCUs are asfollows:

At 70% propeller RPM:

Connects generator to auxiliary DC bus

Switches relay box DC bus 3 and DC bus3 from relay box DC bus 2 to auxiliaryDC bus

Voltage regulation same as main generators

Overvoltage protection (> 32.5 VDC) Undervoltage protection (< 23 1 VDC) Overcurrent protection (220 amps) Field excitation protection same as main

generators

Paralleling same as main generators

Underspeed protection when propeller speeddrops below 70%

Electrical Control PanelThe DC electrical system is monitored on the over-head electrical control panel (Figure 2-11) by twovoltammeters, the battery temperature gage, and thefollowing annunciator warning lights:

GEN OFF BUS (left and right main generators) BUS 1 OFF

BUS 2 OFF

EMERG BUS OFF

CENTRAL BUS OFF

BATTERY OFF BUS

AUX GEN OFF BUS (left and right auxil-iary generators)

TRANSFER FAIL

A voltammeter selector switch permits monitoringof the volts and amps of each main generator, theauxiliary DC bus, main battery, central bus, and APUgenerator.

AC POWERCOMPONENTSInvertersThe alternating current system (Figure 2-12) con-sists of two independently powered inverters locat-ed in the nose section of the aircraft and accessiblethrough the electronic compartment door in thenose wheel well. Each inverter produces 115- and26-VAC, 400-Hz power.

Normally both inverters are energized, but only oneis used to power the AC buses. Inverter No. 1, pow-ered from DC bus 2, is the primary AC power source.

Inverter No. 2, powered from emergency DC bus1, is kept in a powered backup status for invert-er No. 1.

Transfer Control RelaysTwo transfer control relays direct the output ofthe inverters to the appropriate AC buses.

Transfer control relay 1 is powered by the 115-VACoutput of inverter No. 1. Transfer control relay 2is powered by DC bus 2 (the power source forinverter No. 1) and radio master DC bus 2C.




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115-VAC ESS

26-ESS AC

115-VAC EM

26-VAC EM

VSUSTBYHORIZ


BACKUPBATTERYRELAY

BACKUP BATTERY

BACKUPBATT

SWITCH

OFFTEST

ARM

NORM

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL1

TRANSFERCONTROL2

50

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200 200

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200

80

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EMERG

EMERGENCYSWITCHING RELAY

AUXILIARY DC BUS

RBDC BUS 3


RELAY

EMERGENCYSWITCHING


AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2







APUSTART

CONTACTOR


BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY

RMDC BUS 2A

RMDC BUS 2B

RMDC BUS 2C

ON

OFFNORMAL

RM

AHRS 2 DC


EXT POWERCONTACTOR

CENTRAL DC BUS




ON

ON

OFF

OFF

EMERGENCYRM

NORMALRM

RMEMERG DC BUS 1

RMDC BUS 1A

RMDC BUS 1B

RMDC BUS 1C

AHRS 1 DCRMI 2

1 2 AUXGCUs


DC BUS 2

DC BUS 1

RB DC BUS 1

INV 2INV 1

RB DC BUS 2

BUS 3 RELAY

BUS TIECONTACTOR

1

EMERGENCYBUS

CONTACTOR 1

BUS TIECONTACTOR

2

ENGINESTART

CONTACTOR

225


1

MAIN BATTERY

BACKUP BATTERY

GCU

EMERGENCY

STANDBY AC (INV 2)


LEGEND

EMERGENCYBUS

CONTACTOR 2

Figure 2-18. Emergency ModeBoth Main Generators and One Auxiliary Generator Failure



DISTRIBUTIONThe 115/26-VAC inverter output is distributed to fourbuses: two 26-VAC (essential and emergency)and two 115-VAC (essential and emergency) buses.In the event of inverter No. 1 failure, the loss of 115-VAC output causes the transfer control relay toautomatically switch the four AC buses to invert-er No. 2. (A failure of only the 26-VAC output ofinverter No. 1 does not lead to automatic systemtransfer; thus, it is necessary to manually deenergizeinverter No.1. This condition is indicated by theillumination of both essential and emergency 26VAC BUS OFF lights).

CONTROL AND MONITORINGEach inverter is controlled by its respective switchon the electrical panel (Figure 2-12). An INOPannunciator light illuminates in the event of invert-er failure or if the switch is turned off. Each AC bushas an annunciator light to indicate loss of powerto that bus.

ELECTRICAL SYSTEMOPERATIONThere are two modes of operation for the aircraft elec-trical system:

Normal

Emergency

The normal configuration for the aircraft electricalsystem is the normal mode.

Under normal operating conditions and if bothmain generators fail while operating in the normalmode, the system automatically switches, after a 2second delay to the emergency mode.

The electrical system may be manually switched tothe emergency mode by positioning the guarded elec-trical emergency switch to EMERG.

NORMAL MODEBefore Engine StartPrior to engine start, the battery or external powersupplies electrical power to all DC buses (except theauxiliary DC bus) and to both inverters (Figures 2-14 and 2-15). If the APU is available and provid-ed the PWR SELECT switch is set to BATT, the APUgenerator will supply the same buses and charge thebattery (Figure 2-16).

Takeoff and Normal FlightWhen NP reaches 70%, the auxiliary GCUs connectthe auxiliary generators to the auxiliary DC bus.

Once the auxiliary DC bus is powered the bus 3contactor shifts, switching relay box DC bus 3and DC bus 3 from relay box DC bus 2 to the aux-iliary DC bus.

The auxiliary GCUs also switch the primary nav-igation equipment (AHRS 1, AHRS 2, RMI 2,and radio master DC buses 1A and 2C) to theemergency DC buses.

The main generators continue to power the remain-ing buses and charge the battery.

Normal electrical system configuration (NP >70%), is shown in Figure 2-13.

2-22 FOR TRAINING PURPOSES ONLY Revision 4

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115-VAC ESS

26-ESS AC

115-VAC EM

26-VAC EM

VSUSTBYHORIZ


BACKUPBATTERYRELAY

BACKUP BATTERY

BACKUPBATT

SWITCH

OFFTEST

ARM

NORM

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL1

TRANSFERCONTROL2

50

35

80

200 200

15

200

80

35

EMERGEMERGENCY

SWITCHING RELAY

AUXILIARY DC BUS

RBDC BUS 3


RELAY

EMERGENCYSWITCHING


AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2







APUSTART

CONTACTOR


BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY

RMDC BUS 2A

RMDC BUS 2B

RMDC BUS 2C

ON

OFFNORMAL

RM

AHRS 2 DC


EXT POWERCONTACTOR

CENTRAL DC BUS




ON

ON

OFF

OFF

EMERGENCYRM

NORMALRM

RMEMERG DC BUS 1

RMDC BUS 1A

RMDC BUS 1B

RMDC BUS 1C

AHRS 1 DCRMI 2


DC BUS 2

DC BUS 1

RB DC BUS 1

INV 2INV 1

RB DC BUS 2

BUS 3 RELAY

BUS TIECONTACTOR

1

EMERGENCYBUS

CONTACTOR 1

BUS TIECONTACTOR

2

ENGINESTART

CONTACTOR

225


1

BACKUP BATTERY

GCU

EMERGENCY

MAIN BATTERY

STANDBY AC (INV 2)LEGEND

AUXGCUs

2 1

EMERGENCYBUS

CONTACTOR 2

Figure 2-19. Emergency ModeTotal Generator Failure

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115-VAC ESS

26-ESS AC

115-VAC EM

26-VAC EM

VSUSTBYHORIZ


BACKUPBATTERYRELAY

BACKUP BATTERY

BACKUPBATT

SWITCH

OFFTEST

ARM

NORM

115 VAC26 VAC

115 VAC26 VAC

TRANSFERCONTROL1

TRANSFERCONTROL2

50

35

80

200200

15

200

80

35

EMERGEMERGENCY

SWITCHING RELAY

AUXILIARY DC BUS

RBDC BUS 3


RELAY

EMERGENCYSWITCHING


AUX GENCONTACTOR

2

AUX GEN 1 AUX GEN 2







APUSTART

CONTACTOR


BATTERYCONTACTOR

HOT BATTERY BUS

MAINBATTERY

RMDC BUS 2A

RMDC BUS 2B

RMDC BUS 2C

ON

OFFNORMAL

RM

AHRS 2 DC


EXT POWERCONTACTOR

CENTRAL DC BUS




ON

ON

OFF

OFF

EMERGENCYRM

NORMALRM

RMEMERG DC BUS 1

RMDC BUS 1A

RMDC BUS 1B

RMDC BUS 1C

AHRS 1 DCRMI 2


DC BUS 2

DC BUS 1

RB DC BUS 1

INV 2INV 1

RB DC BUS 2

BUS 3 RELAY

BUS TIECONTACTOR

1

EMERGENCYBUS

CONTACTOR 1

BUS TIECONTACTOR

2

ENGINESTART

CONTACTOR

225


1


AC (INV 1)

R MAIN DC GEN

L MAIN DC GEN

BACKUP BATTERY

GCU

MAIN BATTERY

STANDBY AC (INV 2)LEGEND

AUXGCUs

2 1

EMERGENCYBUS

CONTACTOR 2

Figure 2-20. Overcurrent Case 1: Short Circuit, Central DC Bus




Single-Engine FlightThe electrical power distribution for single-engineflight (Figure 2-17) is the same as the normal flightconfiguration.

The DC load on the remaining main generatorshould be reduced to 400 amps if the APU gener-ator is not available.

The remaining auxiliary generator continues tosupply the loads of the auxiliary DC bus, relaybox DC bus 3 and DC bus 3 with no restriction.

EMERGENCY MODEThe electrical system may be switched to the emer-gency mode of operation manually; or it mayswitch automatically with the loss of both main gen-erators (after a 2-second delay).For the switch to occur automatically, the follow-ing conditions must be met:

At least one main generator switch ON

PWR SELECT switch in BATT

Both main generators loss (Line con-tactors open)

NOTETo prevent a reset to the normal modeafter an automatic switch to the emergen-cy mode, select EMERG on the electricalemergency switch prior to turning both maingenerators switches OFF.

In the emergency mode:

The emergency bus contactor opens, dis-connecting the emergency DC buses from relaybox DC bus 2.

The auxiliary transfer relay shifts, connect-ing the emergency DC buses to the auxiliaryDC bus.

The battery contactor opens, disconnectingthe battery from the central DC bus.

The emergency battery contactor closes,connecting the battery to the emergency DCbuses.

The backup battery relay is deenergized,disconnecting the backup buses from thebackup battery.

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flight safety embraer emb-120 brasilia pilot training manual

Documents

flightsafety international

best training possible

hydraulic power systemschapter

aircraft generalchapter

aircraft systemscopyright

auxiliary power unitchapter

fuel systemchapter

air conditioningchapter