How do you verify that the APU's electrical generator is correctly feeding the aircraft buses after start?

How do you verify that the APU's electrical generator is correctly feeding the aircraft buses after start?

• A. Listen for the generator's audible hum.
• B. Check the physical alignment of the generator mount.
• C. Verify the generator control is in auto and that it has a proper rotating speed.
• D. Check generator output parameters (voltage, frequency, current) and confirm bus voltages align with spec and loads are powered.

Answer: (D)

The essential idea is to verify the actual electrical output and the resulting bus conditions, not rely on sounds or appearance. After starting the APU, you confirm the generator is delivering the correct voltage, frequency, and current, and you check that the aircraft buses show the proper voltages within specified tolerances with the expected loads energized. Use the power management or electrical panels to read generator output and bus voltages; ensure the bus voltages match the aircraft’s specs and that essential systems are powered. If these electrical parameters are within tolerance and the buses indicate power, the APU generator is feeding the buses correctly. Audio cues, mounting alignment, or simply having the generator in auto with a spinning rotor do not guarantee proper electrical power by themselves.

The essential idea is to verify the actual electrical output and the resulting bus conditions, not rely on sounds or appearance. After starting the APU, you confirm the generator is delivering the correct voltage, frequency, and current, and you check that the aircraft buses show the proper voltages within specified tolerances with the expected loads energized. Use the power management or electrical panels to read generator output and bus voltages; ensure the bus voltages match the aircraft’s specs and that essential systems are powered. If these electrical parameters are within tolerance and the buses indicate power, the APU generator is feeding the buses correctly. Audio cues, mounting alignment, or simply having the generator in auto with a spinning rotor do not guarantee proper electrical power by themselves.