Systems - Electrical

Question 1

How many batteries does the 737 have

Answer 1

2

Main and Aux

Some aircraft are not equipped with AUX battery

Question 2

What causes DRIVE annunciator to illuminate?

Answer 2

Low oil pressure or under frequency condition in Integrated drive generator

Causes:
IDG failure
Engine shutdown
IDG automatic disconnect due to high oil temp
IDG disconnect through the DISCONNECT switch

Question 3

How long will power last off the standby busses alone?

Answer 3

60min with 2 batteries

30min with 1 battery

Question 4

Instruments and navigations systems available on battery only standby mode

Answer 4

Captain outboard display unit with PFD
Captain inboard display unit with ND
Standby instruments
Left FMC and CDU
Clocks
Left EFIS control panel
VHF NAV 1
ILS 1
Left IRS and GPS
DME 1 
ADF 1
Marker beacon
Transponder 1

Question 5

Two basic principles of AC system operation

Answer 5

No paralleling of AC power sources

A source of power connected to an AC transfer bus automatically disconnects the previous source

Question 6

How many TRs are required to power the total connected load

Answer 6

2

Question 7

What can cause SOURCE light to illuminate?

Answer 7

• Power source to transfer bus has changed without manual input
• Transfer bus is not energized by selected source
• Manual selected source is disconnected
• No source of power to transfer bus

Question 8

Minimum Battery Voltage for APU start

Answer 8

23 Volts