Electrical System

Question 1

Describe Electrical System of C172s

Answer 1

28-volt direct current (DC) electrical system consisting of a belt-driven 60-ampere alternator and a 24-volt main storage battery.

Question 2

Where is battery

Answer 2

The storage battery is located inside the engine cowling on the left firewall.

Question 3

How are alternator and battery controlled

Answer 3

The alternator and battery are controlled through the MASTER switch (ALT and BAT) found near the top of the pilot’s switch panel.

Question 4

How is power distributed through plane?

Answer 4

Power is supplied to most electrical circuits through two primary buses (ELECTRICAL BUS 1 and ELECTRICAL BUS 2), with an Essential Bus and a crossfeedbus connected between the two primary buses to support essential equipment.

Question 5

Is there a secondary battery and if so, where is it store?

Answer 5

The system is equipped with a secondary or “standby” battery located between the firewall and the instrument panel.

Question 6

What does the STBY BATT switch control do and when is it used?

Answer 6

The STBY BATT switch controls power to or from the standby battery.
The standby battery is available to supply power to the Essential Bus in the event that alternator and main battery power sources have both failed.

Question 7

What is the AVIONICS switch and what does it do?

Answer 7

The AVIONICS switch is a two-pole rocker-type switch that controls electrical power to AVIONICS BUS 1 and BUS 2.
Placing either side of the rocker switch in the ON position supplies power to the corresponding avionics bus.

Question 8

When should both the AVIONICS switch be placed in the OFF position

Answer 8

before turning the MASTER switch ON or OFF, starting the engine, or applying an external power source.