A&P Aircraft Electrical Systems Questions and Answers

Question 1

An aircraft's 24-volt lead-acid battery has 12 cells. What is the approximate voltage of each cell when the battery is fully charged?

Accepted Answer

2.1 volts

Answer

A fully charged lead-acid battery cell has a nominal voltage of approximately 2.1 to 2.2 volts. In a 24-volt battery, there are 12 cells connected in series (12 cells x 2.1 volts/cell = 25.2 volts).

Question 2

During a pre-flight inspection, a pilot notices that a push-to-reset circuit breaker for the landing light circuit has 'popped.' What is the primary advantage of a circuit breaker over a fuse in this scenario?

Accepted Answer

Circuit breakers can be reset, while fuses must be replaced.

Answer

The main advantage of a circuit breaker is its resettability. If a circuit breaker trips, it can be reset (after a cooling-off period and troubleshooting) without needing a replacement part, unlike a fuse which must be replaced once it blows.

Question 3

Which of the following is a primary advantage of an alternator over a generator in a light aircraft electrical system?

Accepted Answer

Alternators are lighter and produce more stable voltage at low engine RPMs.

Answer

Alternators are generally lighter than generators of similar output and are capable of producing their rated power at lower engine speeds. This is a significant advantage during taxi and other low-RPM operations, preventing battery discharge.

Question 4

According to AC 43.13-1B, when routing electrical wiring, what is the maximum interval between support clamps for a wire bundle?

Accepted Answer

24 inches

Answer

FAA Advisory Circular AC 43.13-1B, Chapter 11, states that wires and cables should be supported by suitable clamps, grommets, or other devices at intervals of not more than 24 inches, except when contained in troughs, ducts, or conduits.

Question 5

A technician is troubleshooting an electrical issue and needs to distribute power from a single source to multiple circuits. What component is specifically designed for this purpose in an aircraft electrical system?

Accepted Answer

A bus bar

Answer

A bus bar is a metallic strip or bar that serves as a common connection point for multiple electrical circuits, distributing electricity from a single source (like a generator or battery) to various systems.

A&P - Certified Airframe and Powerplant Mechanics Practice Test

A&P - Certified Airframe and Powerplant Mechanics Practice Test

A&P Aircraft Electrical Systems Questions and Answers