The Secondary Power line powers which group of systems?

• A. Main bus, Avionics 2 bus, Non-Essential bus, Cabin Bus, Landing gear, RH windshield de-ice, Vapor Cycle cooling, Under floor heater
• B. Essential Bus only
• C. Avionics 2 bus only
• D. Cabin heat and Flaps

Answer: (A)

The thing being tested is how the aircraft's electrical system uses a Secondary Power line to keep a useful set of systems alive when main power isn’t fully available. The Secondary Power line is designed to support a group of buses and subsystems that you’d want to remain powered for continued operation and safety in degraded electrical conditions. It powers the Main bus and Avionics 2 bus, as well as the Non-Essential and Cabin buses, plus several important equipment items: the Landing gear, the right windshield de-ice, Vapor Cycle cooling, and the Under floor heater. Keeping these alive allows you to extend gear operation, maintain visibility, and provide environmental control even when primary power is limited.

This grouping isn’t limited to just the essential bus, or only Avionics 2, or only cabin heat. Those narrower options would miss items like the landing gear and windshield de-ice, which are included in the secondary-power-supported set.