When the APU is shut down by turning OFF, what is the status of the APU GEN OFF BUS light?

When the APU is shut down by turning OFF, what is the status of the APU GEN OFF BUS light?

• A. Illuminated
• B. Extinguished
• C. Flashes
• D. Remains unchanged

Answer: (B)

The APU GEN OFF BUS light shows whether the APU’s generator is connected to the electrical bus. If the APU is running and not feeding the bus, the light would illuminate to warn that power isn’t on the bus from the APU. When you shut the APU off by turning OFF, the generator is no longer in play and there’s no “off-bus” condition to indicate, so the light goes out. In this state it’s not providing power to the bus and there’s no fault or abnormal condition triggering the lamp, so the indicator remains extinguished.

The APU GEN OFF BUS light shows whether the APU’s generator is connected to the electrical bus. If the APU is running and not feeding the bus, the light would illuminate to warn that power isn’t on the bus from the APU. When you shut the APU off by turning OFF, the generator is no longer in play and there’s no “off-bus” condition to indicate, so the light goes out. In this state it’s not providing power to the bus and there’s no fault or abnormal condition triggering the lamp, so the indicator remains extinguished.