Boeing B737 MAX - Electrical

Which is the power source for the AC standby bus?

Battery Bus through the Static Inverter under normal conditions

AC main bus 1

Transfer bus 1 under normal conditions

Transfer bus 2

Correct! Wrong!

Illumination of the GEN BUS OFF light indicates:

The associated transfer bus is not powered.

The IDG is not supplying power to its associated Transfer bus.

The associated generator bus is not powered.

The generator is not supplying power to its associated generator bus.

Correct! Wrong!

The switched hot battery bus is powered whenever:

TR1 is powered.

Transfer bus 1 is powered.

AC ground service bus is powered.

The battery switch is ON.

Correct! Wrong!

Either generator or the APU can power both transfer buses. In the event a power source fails, what is required for that transfer bus to be powered by the opposite transfer bus power source?

The battery switch must be OFF.

The BUS TRANS switch must be in the AUTO position.

The generator switch must be OFF.

The battery switch must be ON.

Correct! Wrong!

Illumination of the STANDBY POWER OFF light indicates:

DC bus 2 unpowered

AC standby bus unpowered

DC bus 1 unpowered

Hot battery bus unpowered

Correct! Wrong!

Both AC Transfer busses can be powered simultaneously by:

A single IDG on the ground or inflight and the APU generator while on the ground or inflight

No single source can power both AC Transfer busses simultaneously

A single IDG on the ground or inflight

The APU generator while on the ground or inflight

Correct! Wrong!

When the STANDBY POWER Switch is OFF:

The STANDBY PWR OFF light will be extinguished

Automatic switching is provided from normal power sources to alternate power sources

The Static Inverter provides 28V DC power to Transfer Bus No.1.

The STANDBY PWR OFF light will be illuminated

Correct! Wrong!

The TR3 Disconnect Relay:

Automatically opens at glide slope capture during a Flight Director or Autopilot ILS approach

Normally powers the Battery Charger and backs-up TR units 1 & 2 through a diode

Will trip off when AC volts reaches 26 volts (+ or - 4 Volts) as dispalyed on the AC Voltmeter.

Must be manually opened using the BUS TRANSFER Switch during a Flight Director approach

Correct! Wrong!

During cruise, one engine driven generator drops off-line. Indications that the crew should see include:

A TRANSFER BUS OFF light and a GEN OFF BUS light

All statements are correct.

Illumination of the fuel pump, probe heat, respective hydraulic pumps powered by the associated Transfer bus

A SOURCE OFF light and a GEN OFF BUS light

Correct! Wrong!

Which bus supplies electrical power to the auxiliary battery charger?

Transfer bus 1

AC ground service bus 2

Transfer bus 2

AC ground service bus 1

Correct! Wrong!

Both On the ground and in flight a amber ELEC light comes on to indicate that a fault exists in DC power system or standby power system.

False.

True.

Correct! Wrong!

The ELEC light is inhibited in flight.

The IDGs contain the generator and drive in a common housing, and are lubricated and cooled by a external oil system attached to the gearbox.

False.

True.

Correct! Wrong!

The IDGs contain the generator and drive in a common housing, and are lubricated and cooled by a self-contained oil system.

The 115V AC Standby Bus is powered by:

The Battery through the Static Inverter with a failure of both engine driven generators.

The 115V Transfer Bus No.1 under normal conditions.

The 115V Transfer Bus No.1 under normal conditions and the Battery through the Static Inverter with a failure of both engine driven generators.

The Battery Bus through the Static Inverter under normal conditions.

Correct! Wrong!

One basic principle of operation for the B737 electrical system is:

There is no paralleling of the AC power sources.

All generator bus sources can be automatically connected by the Standby Power System.

There is no paralleling of any power source.

An AC power source may be used in parallel with a DC power source.

Correct! Wrong!

It is possible to power one transfer bus with external power and the other transfer bus with the APU?

No.

Yes.

Correct! Wrong!

AUTOMATIC LOAD SHEDDING (ENGINE GENERATORS) - For single generator operation, the system is designed to shed electrical load incrementally based on actual load sensing. When configuration changes to more source capacity (two generator operation), automatic load restoration of the main busses, galley busses and IFE buses occurs. Manual restoration of galley and main bus power can be attempted by:

Moving the CAB/UTIL Power Switch to OFF for 5 minutes minimum, then back ON.

Moving the CAB/UTIL Power Switch to OFF for 3 minutes minimum, then back ON.

Moving the CAB/UTIL Power Switch to OFF for 2 minutes minimum, then back ON.

Moving the CAB/UTIL Power Switch to OFF, then back ON.

Correct! Wrong!

A high oil temperature in the IDG would cause an automatic disconnect of the IDG.rnrnrn

True.

False.

Correct! Wrong!

The purpose of the cross tie relay is to:

Isolate DC bus 1 from DC bus 2

Disconnect TR2 and TR3

Isolate transfer bus 1 and 2

Disconnect TR1 and TR3

Correct! Wrong!

The main battery charger is powered through:

Transfer Bus 1

AC main bus 1

AC ground service bus 2

DC bus 1

Correct! Wrong!

In flight, if the APU is supplying both AC Transfer busses, positioning the BUS TRANS switch to OFF will:

Cause AC Transfer bus No.2 to lose power

Cause both AC Transfer busses to lose power

Not cause either AC Transfer bus to fail.

Cause AC Transfer bus No.1 to lose power

Correct! Wrong!

DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery and each of the 3 TRs. The Standby power and battery bus displays only Dc voltage. Normal indication is ______ volts

26 +/- 6

24 +/- 4

24 +/-2

26 +/-4

Correct! Wrong!

The TR UNIT will illuminate in flight if:

Any TR unit fails.

TR3 fails.

TR2 fails.

TR1 fails or TR2 and TR3 fail.

Correct! Wrong!

Transformer rectifier (TR) units and the main battery/battery charger supply DC power.

False.

True.

Correct! Wrong!

The purpose of the AC ground service bus is to power:

The battery charger

The utility outlets

All statements are correct.

The cabin lighting

Correct! Wrong!

What is the source of power for TR2?

Transfer bus 1.

AC Standby bus

Transfer bus 2.

Transfer bus 2 or Transfer bus 1.

Correct! Wrong!

What is the purpose of the GROUND SERVICE switch?

Provides automatic control of ground service bus.

Provide manual control of ground service bus.

Provide automatic control of ground service busses.

Provide manual control of ground service busses.

Correct! Wrong!

Enables servicing airplane using external power without activating AC transfer busses.rn

DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery and each of the three TRs. The standby power and battery bus displays only DC voltage. Normal indication is:

26 +/- 4 volts.

12 +/- 4 volts.

14 +/- 4 volts.

24 +/- 10 volts.

Correct! Wrong!

During primary charge cycle operation battery voltage can be as high as 30 +/- 3 volts

Normal AC voltmeter indication for the APU generator with the AC busses loaded:

115 to 125 volts.rn

100 to 125 volts.

110 to 125 volts.

10 to 135 volts.

Correct! Wrong!

DC busses powered from the battery following a loss of both generators are:

DC standby Bus, Hot Battery Bus & Switched hot battery bus.

Battery bus, DC Standby bus, Hot battery bus.

Battery bus, DC Standby bus, Hot battery bus & Switched hot battery bus (even when the battery switch is OFF).

Battery bus, DC Standby bus, Hot battery bus & Switched hot battery bus.

Correct! Wrong!

AUTOMATIC LOAD SHEDDING (ENGINE GENERATORS) - For single generator operation, the system is designed to shed electrical load incrementally based on actual load sensing. What is the first bus that is shed?

The AC standby bus is shed first.

The galleys and main bus on transfer bus 2 are shed first

The galleys and main bus on transfer bus 1 are shed first

The DC standby bus is shed first.

Correct! Wrong!

The ELEC light will illuminate in flight if:

A fault exists in the AC, DC or the Standby system.

The ELEC light only operates on the ground.

A fault exists in the AC or Standby power system.

A fault exists in the DC or Standby system.

Correct! Wrong!

The Engine Integrated Drive Generators (IDGs):

Allow the generator to maintain a constant speed throughout the normal range of operation

Are used in conjunction with a separate generator drive unit (CSD)

Adjust varying generator speeds to maintain a constant frequency throughout normal range of operation

Operate whenever the engine is operating and cannot be completely isolated from their associated generator.

Correct! Wrong!

When the aircraft batteries is the only source of power:

Both the Captain's and First Officer's PFD/ND displays remain operative but only DEU No 1 is powered until the battery is discharged

The Captain's inboard and the First Officer's inboard and outboard displays are inoperative

The Captain's inboard and outboard displays operate until the battery is discharged

The Captain's inboard and outboard displays operate until the battery is discharged and the First Officer's inboard and outboard displays operate for a minimum of 5 minutes

Correct! Wrong!

Illumination of the BAT DISCHARGE light indicates:

The battery bus is not powered.

The DC meter is in the BAT position with the battery switch ON.

Excessive battery discharge is detected with the battery switch ON.

The battery is being overcharged.

Correct! Wrong!

In flight if APU is the only source of electrical power:

No galley busses are automatically shed

Only galley bus A & B are automatically shed

Only galley bus C & D are automatically shed

All galley busses are automatically shed

Correct! Wrong!

Illumination of the blue GEN OFF BUS light indicates:

he associated transfer bus is not powered

The associated generator bus is not powered

The generator is not supplying power to its associated generator bus.

The IDG is not supplying power to its associated transfer bus

Correct! Wrong!

With external DC power connected to the external DC power receptacle:

All circuits normally powered by the battery are powered.

The APU can be started using DC external power.

The battery is paralleled with the DC External power source.

There is no external DC power receptacle.rn

Correct! Wrong!

With the STANDBY switch in the AUTO position, the loss of all engine or APU electrical power results in the automatic switching from the normal power source to the alternate source for standby power:

Inflight only.

Either inflight or on the ground.

On the ground only.

Will not occur.

Correct! Wrong!

Galley busses are powered from:

The generator busses.

The Battery bus.

The AC Transfer busses.

The main busses.

Correct! Wrong!

Because engine generators power the transfer busses directly, and transfer busses are connected by a bus tie system, the loss of an engine driven generator will not necessarily result in the loss of any bus(ses).

False.

True.

Correct! Wrong!

The auxiliary battery operates in parallel with the main battery when the battery is powering the standby bus.

False.

True.

Correct! Wrong!

On the ground, with the BATTERY switch OFF and STANDBY POWER Switch in BAT, the switched hot battery bus is:

Not powered

Correct! Wrong!

The cross bus tie relay:

Will trip off when AC volts reaches 26 volts (plus or minus 4 volts) as displayed on the AC voltmeter

Opens up if BUS TRANSFER switch is moved to OFF

Must be manually opened using the BUS TRANSFER Switch during a Flight Director approach

Normally powers the Battery Charger and backs-up TR units 1 and 2 through a diode

Correct! Wrong!

The illumination of the GND POWER AVAILABLE light indicates:

Ground power is connected however no airplane power quality is measured.

The external power bus is powered by a ground power supply.

The Ground Service Bus is powered by a ground power supply.

Ground power is connected and meets airplane power quality standards.

Correct! Wrong!

What is the significance of an illuminated ELEC light?

Two or more TRs have failed.

The DC system or standby system equipment has failed.

One of the three TRs has failed.

The battery is discharged.

Correct! Wrong!

For ground service, a ground service switch is available on:

Forward attendantu00b4s panel

The overhead panel in the flight deck.

Aft overhead panel on the Flight Deck

Aft attendantu00b4s panel

Correct! Wrong!

If the AC source powering a transfer bus fails, the transfer bus will remain unpowered.

False.

True

Correct! Wrong!

The GROUND POWER AVAILABLE light will extinguish when:

The GROUND POWER switch is positioned ON

The GROUND SERVICE switch is positioned ON

The pneumatic ground cart is disconnected

The AC ground power cart has been disconnected

Correct! Wrong!

The main and auxiliary batteries also provide backup power for the DC standby system only.

False.

True.

Correct! Wrong!

The main and auxiliary batteries also provide backup power for the AC and DC standby system.

After the loss of all generators, two fully charged batteries have sufficient capacity to provide standby power for a minimum of:Two fully charged batteries have sufficient capacity to provide standby power forrna minimum of

45 minutes

60 minutes

20 minutes

30 minutes

Correct! Wrong!

Each IDG supplies its own bus system in normal operation and can also supply essential and non-essential loads of the opposite side bus system when one IDG is inoperative.

True.

False.

Correct! Wrong!

On the ground, with the battery switch OFF and STANBY POWER Switch in AUTO, the Battery Bus is:

Not powered.

Correct! Wrong!

What is the source of power for TR3?

Transfer bus 2.

AC standby bus.

Transfer bus 1 or 2.

Transfer bus 1.

Correct! Wrong!

The TR3 cross bus tie relay automatically opens at glide slope capture to:

Provide more power to DC bus 1.

Prevent a single bus failure from affecting both navigation receivers and Flight Control Computers (FCCs).

Ensure that the STANDBY DC is powered.

Provide more power to the AC STANDBY Bus.

Correct! Wrong!

Boeing 737 MAX - Electrical

Quiz

Boeing B737 MAX - Electrical

Which is the power source for the AC standby bus?

Illumination of the GEN BUS OFF light indicates:

The switched hot battery bus is powered whenever:

Either generator or the APU can power both transfer buses. In the event a power source fails, what is required for that transfer bus to be powered by the opposite transfer bus power source?

Illumination of the STANDBY POWER OFF light indicates:

Both AC Transfer busses can be powered simultaneously by:

When the STANDBY POWER Switch is OFF:

The TR3 Disconnect Relay:

During cruise, one engine driven generator drops off-line. Indications that the crew should see include:

Which bus supplies electrical power to the auxiliary battery charger?

Both On the ground and in flight a amber ELEC light comes on to indicate that a fault exists in DC power system or standby power system.

The IDGs contain the generator and drive in a common housing, and are lubricated and cooled by a external oil system attached to the gearbox.

The 115V AC Standby Bus is powered by:

One basic principle of operation for the B737 electrical system is:

It is possible to power one transfer bus with external power and the other transfer bus with the APU?

A high oil temperature in the IDG would cause an automatic disconnect of the IDG.rnrnrn

The purpose of the cross tie relay is to:

The main battery charger is powered through:

In flight, if the APU is supplying both AC Transfer busses, positioning the BUS TRANS switch to OFF will:

DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery and each of the 3 TRs. The Standby power and battery bus displays only Dc voltage. Normal indication is ______ volts

The TR UNIT will illuminate in flight if:

Transformer rectifier (TR) units and the main battery/battery charger supply DC power.

The purpose of the AC ground service bus is to power:

What is the source of power for TR2?

What is the purpose of the GROUND SERVICE switch?

DC voltage and amperage may be read on the DC voltmeter and ammeter for the battery and each of the three TRs. The standby power and battery bus displays only DC voltage. Normal indication is:

Normal AC voltmeter indication for the APU generator with the AC busses loaded:

DC busses powered from the battery following a loss of both generators are:

AUTOMATIC LOAD SHEDDING (ENGINE GENERATORS) - For single generator operation, the system is designed to shed electrical load incrementally based on actual load sensing. What is the first bus that is shed?

The ELEC light will illuminate in flight if:

The Engine Integrated Drive Generators (IDGs):

When the aircraft batteries is the only source of power:

Illumination of the BAT DISCHARGE light indicates:

In flight if APU is the only source of electrical power:

Illumination of the blue GEN OFF BUS light indicates:

With external DC power connected to the external DC power receptacle:

With the STANDBY switch in the AUTO position, the loss of all engine or APU electrical power results in the automatic switching from the normal power source to the alternate source for standby power:

Galley busses are powered from:

Because engine generators power the transfer busses directly, and transfer busses are connected by a bus tie system, the loss of an engine driven generator will not necessarily result in the loss of any bus(ses).

The auxiliary battery operates in parallel with the main battery when the battery is powering the standby bus.

On the ground, with the BATTERY switch OFF and STANDBY POWER Switch in BAT, the switched hot battery bus is:

The cross bus tie relay:

The illumination of the GND POWER AVAILABLE light indicates:

What is the significance of an illuminated ELEC light?

For ground service, a ground service switch is available on:

If the AC source powering a transfer bus fails, the transfer bus will remain unpowered.

The GROUND POWER AVAILABLE light will extinguish when:

The main and auxiliary batteries also provide backup power for the DC standby system only.

After the loss of all generators, two fully charged batteries have sufficient capacity to provide standby power for a minimum of:Two fully charged batteries have sufficient capacity to provide standby power forrna minimum of

Each IDG supplies its own bus system in normal operation and can also supply essential and non-essential loads of the opposite side bus system when one IDG is inoperative.

On the ground, with the battery switch OFF and STANBY POWER Switch in AUTO, the Battery Bus is:

What is the source of power for TR3?

The TR3 cross bus tie relay automatically opens at glide slope capture to: