AME - Aircraft Maintenance Engineer Aircraft Electrical Systems Questions and Answers

Question 1

What is the primary function of a Constant Speed Drive (CSD) unit in an aircraft's AC electrical system?

Accepted Answer

To convert variable engine RPM into a constant generator RPM.

Answer

The primary purpose of a Constant Speed Drive (CSD) is to take the variable rotational speed from the engine's accessory gearbox and convert it into a constant speed for the AC generator. This ensures the generator produces a stable frequency (typically 400 Hz) required by aircraft systems, regardless of changes in engine thrust.

Question 2

During a routine inspection of a 24-volt lead-acid battery, an AME notices a significant difference in specific gravity readings between individual cells (e.g., one cell is 1.275 while another is 1.220). What is the most appropriate action?

Accepted Answer

Replace the battery as it is likely nearing the end of its service life.

Answer

A specific gravity difference of 0.050 or more between cells in a lead-acid battery indicates that the battery is approaching the end of its useful life and should be considered for replacement. Topping off with water or simply recharging will not fix the underlying issue of a failing cell. Adding acid is never the correct procedure for adjusting specific gravity in the field.

Question 3

In accordance with 14 CFR Part 25, if a fuse is essential for safety in flight and is accessible to the flight crew, what is the minimum number of spare fuses that must be carried on board?

Accepted Answer

At least 50% of the number of fuses of each required rating.

Answer

14 CFR § 25.1357(d) states: "Where fuses are used, there must be spare fuses for use in flight equal to at least 50% of the number of fuses of each rating required for complete circuit protection." This regulation ensures that sufficient spares are available for critical systems.

Question 4

Which of the following describes a 'trip-free' circuit breaker?

Accepted Answer

A circuit breaker that will open a circuit even if the operating control is held in the 'ON' position.

Answer

A 'trip-free' circuit breaker is a safety feature designed to ensure that it will open the circuit during an overload or fault condition, regardless of whether the manual operating lever or button is held in the closed (ON) position. This prevents the crew from forcing a circuit to remain closed against a persistent fault.

Question 5

An aircraft is being prepared for flight at a remote station without ground power available. The AME needs to power the ground handling bus to operate the cargo bay lights and refueling system. Which power source would typically be used in this scenario?

Accepted Answer

The Auxiliary Power Unit (APU) generator.

Answer

The ground handling bus is typically powered by the APU generator or an external power unit. Since external power is unavailable, the APU would be started to provide electrical power for ground operations like cargo lighting and refueling without needing to start the main engines.

AME - Aircraft Maintenance Engineer Practice Test

AME - Aircraft Maintenance Engineer Practice Test

AME - Aircraft Maintenance Engineer Aircraft Electrical Systems Questions and Answers