AET AET Aircraft Power Systems

Question 1

In a typical general aviation aircraft, what is the primary function of the aircraft's alternator?

Accepted Answer

To charge the battery and power the electrical bus during engine operation

Answer

The alternator charges the battery and supplies electrical power to the aircraft's bus systems whenever the engine is running above a threshold RPM.

Question 2

What is the nominal voltage of a standard 14-volt aircraft electrical system when measured at the bus with the alternator online?

Accepted Answer

13.8–14.5 volts

Answer

A 14V system typically operates at 13.8–14.5 volts at the bus when the alternator is charging, slightly above the 12V battery nominal voltage to maintain a charging state.

Question 3

Which component in an aircraft's DC power system prevents the battery from discharging through the alternator when the alternator output is lower than battery voltage?

Accepted Answer

Isolation diode or split-bus relay

Answer

An isolation diode or split-bus relay prevents reverse current flow from the battery through the alternator when alternator output drops below battery voltage.

Question 4

What is the typical voltage output of an aircraft's 28V DC bus system when fully regulated?

Accepted Answer

27.5–28.5 volts

Answer

A regulated 28V system operates between approximately 27.5 and 28.5 volts to properly charge 24V batteries while powering the aircraft's electrical loads.

Question 5

In a constant-speed drive (CSD) generator system found on transport-category aircraft, what does the CSD unit do?

Accepted Answer

Maintains constant generator shaft speed regardless of engine RPM

Answer

The CSD maintains a constant output shaft speed to the generator regardless of engine RPM changes, allowing the AC generator to produce a stable 400 Hz frequency.

(AET) Aircraft Electronics Technician Practice Test

(AET) Aircraft Electronics Technician Practice Test

AET AET Aircraft Power Systems