Electrical Systems

Question 1

How many electrical generators are there on the 737?

Answer 1

3 total: 2 engine-driven generators and 1 APU-driven generator.

Question 2

How many power sources may be available to an aircraft parked at its gate?

Answer 2

6 total:
* 2 engine-driven generators
* 1 APU generator
* 2 batteries
* An external plug-in (GPU – Ground Power Unit)

Question 3

How many power sources are available to an aircraft in-flight?

Answer 3

5 total:
* 2 engine-driven generators
* 2 batteries
* APU

Question 4

What kind of battery does the 737 have?

Answer 4

24-volt nickel cadmium battery with an auxiliary battery.

Question 5

What is an IDG?

Answer 5

IDG – Integrated Drive Generator; maintains a constant 12,000 rpm on a generator.

Question 6

How is electrical power distributed by the generators on the 737?

Answer 6

All generators supply power to the Synch Bus which powers all electrical systems.

Question 7

If only one generator is online and connected to the Synch Bus, what percentage of power does it provide?

Answer 7

100% of the aircraft’s power needs.

Question 8

How long will the battery work for if both generators are lost in flight?

Answer 8

60 minutes total: 30 minutes on the primary battery and 30 minutes on the auxiliary battery.

Question 9

Can the 737 be dispatched if both electrical generators are inoperative?

Answer 9

Check the MELs!!

Question 10

How can you convert AC to DC power?

Answer 10

Using the transformer rectifier to convert 115-volt AC to 28-volt DC.

Question 11

How can you convert DC to AC power?

Answer 11

Using a static inverter to convert 24-volt DC to 115-volt AC.